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AS03-adjuvanted versus non-adjuvanted inactivated trivalent infl uenza vaccine against seasonal infl uenza in elderly people: a phase 3 randomised trialJanet E McElhaney, Jiri Beran*, Jeanne-Marie Devaster*, Meral Esen*, Odile Launay*, Geert Leroux-Roels*, Guillermo M Ruiz-Palacios*, Gerrit A van Essen*, Adrian Caplanusi†, Carine Claeys†, Christelle Durand†, Xavier Duval†, Mohamed El Idrissi†, Ann R Falsey†, Gregory Feldman†, Sharon E Frey†, Florence Galtier†, Shinn-Jang Hwang†, Bruce L Innis†, Martina Kovac†, Peter Kremsner†, Shelly McNeil†, Andrzej Nowakowski†, Jan Hendrik Richardus†, Andrew Trofa†, Lidia Oostvogels, for the Infl uence65 study group

SummaryBackground We aimed to compare AS03-adjuvanted inactivated trivalent infl uenza vaccine (TIV) with non-adjuvanted TIV for seasonal infl uenza prevention in elderly people.

Methods We did a randomised trial in 15 countries worldwide during the 2008–09 (year 1) and 2009–10 (year 2) infl uenza seasons. Eligible participants aged at least 65 years who were not in hospital or bedridden and were without acute illness were randomly assigned (1:1) to receive either AS03-adjuvanted TIV or non-adjuvanted TIV. Randomisation was done in an internet-based system, with a blocking scheme and stratifi cation by age (65–74 years and 75 years or older). Participants were scheduled to receive one vaccine in each year, and remained in the same group in years 1 and 2. Unmasked personnel prepared and gave the vaccines, but participants and individuals assessing any study endpoint were masked. The coprimary objectives were to assess the relative effi cacy of the vaccines and lot-to-lot consistency of the AS03-adjuvanted TIV (to be reported elsewhere). For the fi rst objective, the primary endpoint was relative effi cacy of the vaccines for prevention of infl uenza A (excluding A H1N1 pdm09) or B, or both, that was confi rmed by PCR analysis in year 1 (lower limit of two-sided 95% CI had to be greater than zero to establish superiority). From Nov 15, to April 30, in both years, participants were monitored by telephone or site contact and home visits every week or 2 weeks to identify cases of infl uenza-like illness. After onset of suspected cases, we obtained nasal and throat swabs to identify infl uenza RNA with real-time PCR. Effi cacy analyses were done per protocol. This trial is registered with ClinicalTrials.gov, number NCT00753272.

Findings We enrolled 43 802 participants, of whom 21 893 were assigned to and received the AS03-adjuvanted TIV and 21 802 the non-adjuvanted TIV in year 1. In the year 1 effi cacy cohort, fewer participants given AS03-adjuvanted than non-adjuvanted TIV were infected with infl uenza A or B, or both (274 [1·27%, 95% CI 1·12–1·43] of 21 573 vs 310 [1·44%, 1·29–1·61] of 21 482; relative effi cacy 12·11%, 95% CI –3·40 to 25·29; superiority not established). Fewer participants in the year 1 effi cacy cohort given AS03-adjuvanted TIV than non-adjuvanted TIV were infected with infl uenza A (224 [1·04%, 95% CI 0·91–1·18] vs 270 [1·26, 1·11–1·41]; relative effi cacy 17·53%, 95% CI 1·55–30·92) and infl uenza A H3N2 (170 [0·79, 0·67–0·92] vs 205 [0·95, 0·83–1·09]; post-hoc analysis relative effi cacy 22·0%, 95% CI 5·68–35·49).

Interpretation AS03-adjuvanted TIV has a higher effi cacy for prevention of some subtypes of infl uenza than does a non-adjuvanted TIV. Future infl uenza vaccine studies in elderly people should be based on subtype or lineage-specifi c endpoints.

Funding GlaxoSmithKline Biologicals SA.

IntroductionThe burden of infl uenza and infl uenza-related com-plications in elderly people is much higher than in other age groups,1,2 and infl uenza vaccines seem to be less eff ective in older adults than in younger adults.3,4 However, most understanding of infl uenza vaccines in elderly populations is based on observational studies, which have shown that vaccination is eff ective against infl uenza-related complications in elderly people living in long-term care facilities, but that the eff ect in the community is more modest.3,5 In a study of data for ten infl uenza seasons in the USA in the 1990s,3 vaccination

reduced the risk of infl uenza-related hospital admission in community-based elderly people. However, a review of data from 1966–20095,6 showed that vaccination was not eff ective against infl uenza, infl uenza-like illness, or pneumonia in community-based populations aged at least 65 years.

Although few vaccine effi cacy and eff ectiveness studies have been done in elderly adults, the substantial burden of infl uenza in this population despite widespread vaccination suggests that vaccines with increased effi cacy are needed.1–3 The formulation of vaccines for H5N1 infl uenza and pandemic infl uenza A

Lancet Infect Dis 2013; 13: 485–96

Published OnlineMarch 19, 2013http://dx.doi.org/10.1016/S1473-3099(13)70046-X

See Comment page 466

*Listed in alphabetical order

†Also listed in alphabetical order

Health Sciences North and Advanced Medical Research Institute of Canada, Sudbury, ON, Canada (Prof J E McElhaney MD); Vaccination and Travel Medicine Centre, Hradec Kralove, Czech Republic (Prof J Beran MD); GlaxoSmithKline Vaccines, Rixensart, Belgium (J-M Devaster MD, C Durand MSc, M Kovac MD); Institut für Tropenmedizin, Tübingen, Germany (M Esen MD, P Kremsner MD); Inserm, French network of clinical investigation in vaccinology, Paris, France (Prof O Launay MD); Université Paris-Descartes, Paris, France (Prof O Launay); Inserm, CIC BT505, Paris, France (Prof O Launay); Assistance Publique-Hôpitaux de Paris, Hôpital Cochin, CIC de Vaccinologie Cochin-Pasteur, Paris, France (Prof O Launay); Centre for Vaccinology, Ghent University and Ghent University Hospital, Ghent, Belgium (Prof G Leroux-Roels MD); Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico (G M Ruiz-Palacios MD); Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands (G A van Essen MD); GlaxoSmithKline Vaccines, Wavre, Belgium (A Caplanusi MD, C Claeys MD,

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M El Idrissi MSc, L Oostvogels MD); Hôpital

Bichat Claude Bernard, GH BICHAT, Paris, France

(Prof X Duval MD); Inserm, CIC 007, French network of clinical

investigation in vaccinology, Paris, France (Prof X Duval);

University of Rochester Medical Center, Rochester, NY,

USA (Prof A R Falsey MD); S Carolina Pharmaceutical Research, Spartanburg, SC, USA (G Feldman MD); Saint Louis University Medical Center, St Louis, MO, USA (Prof S E Frey MD); CHRU de Montpellier, Hôpital Saint Eloi, Montpellier, France (F Galtier MD); Inserm, CIC 1001, French network of clinical investigation in vaccinology, Montpellier, France (F Galtier); Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (Prof S-J Hwang MD); National

Yang-Ming University School of Medicine, Taipei, Taiwan

(Prof S-J Hwang); GlaxoSmithKline Vaccines, King

of Prussia, PA, USA (B L Innis MD, A Trofa MD);

VG Site Infectious Diseases, Queen Elizabeth Health

Sciences Centre, Dalhousie University, Halifax, NS, Canada

(Prof S McNeil MD); Family Medicine Centre, Lubartów,

Poland (A Nowakowski PhD); Department of Gynaecology and Oncologic Gynaecology,

Military Institute of Medicine, Warsaw, Poland

(A Nowakowski); and GGD Rotterdam-Rijnmond,

Rotterdam, Netherlands (Prof J H Richardus PhD)

Correspondence to:Dr Lidia Oostvogels,

GlaxoSmithKline Vaccines, Parc de la Noire Epine, 1300 Wavre, Belgium

lidia.oostvogels@gsk.com

For study protocol see http://www.gsk-clinicalstudyregister.

com/protocol_detail.jsp?protocolId=106372&studyId=BFCEEC2A-7A47-49B0-B597-17A70FADA7DE&compound=Infl uenza+Vacci

ne+%28Split+Virion%2C+Inactivated%29

H1N1 with the oil-in-water adjuvant system AS03 increases immuno genicity compared with non-adjuvanted vaccine in adults aged 18–64 years, and AS03-adjuvanted pandemic infl uenza vaccines are highly immunogenic in elderly people.7–11 A phase 2 study of eight adjuvanted inactivated trivalent infl uenza vaccine (TIV) formulations versus non-adjuvanted TIV in elderly people has shown that addition of an adjuvant enhanced immunogenicity (unpublished): TIV formulated with AS03B provided the best balance between the immune response and reactogenicity.

We assessed effi cacy, immunogenicity, and safety of AS03-adjuvanted versus non-adjuvanted TIV for pre-vention of infl uenza A and B in community-based individuals aged at least 65 years. Here, we present the analyses of vaccine effi cacy, reactogenicity, and safety.

MethodsStudy design and participantsWe did a randomised trial in Belgium, Canada, the Czech Republic, Estonia, France, Germany, Mexico, Norway, Poland, Romania, Russia, Taiwan, the Nether-lands, the UK, and the USA during the 2008–09 (year 1) and 2009–10 (year 2) infl uenza seasons. The study began on Sept 15, 2008, and the last follow-up event was on Oct 5, 2010. Eligible participants were aged at least 65 years, were not in hospital or bedridden, and were without acute illness. We enrolled ambulatory individuals whose health was stable and who were community-based or living in a retirement home but could mix in the community.

Individuals who had received investigational adjuvanted seasonal or pandemic infl uenza vaccine in the previous 3 years were excluded. Participants could have received licensed infl uenza vaccines before February, 2008. After the widespread emergence of the 2009 infl uenza A H1N1 pandemic virus, the planned analysis was revised on Aug 4, 2009, by protocol amendment to exclude cases of infl uenza caused by that strain. In September, 2009, the study protocol was amended to allow vaccination against the pandemic strain if at least 14 days before or after study vaccines.

All participants provided informed written consent. The study protocol was approved by independent ethics committees or local or central institutional review boards. The study was done in accordance with good clinical practice, the principles of the Declaration of Helsinki, and all regulatory requirements of participating countries.

Randomisation and maskingThe study sponsor used a blocking scheme to randomly assign participants (1:1) at each site to receive an AS03-adjuvanted TIV or a non-adjuvanted TIV. Participants who were assigned to receive AS03-adjuvanted TIV were further randomly assigned (1:1:1) to one of three vaccine lots (ie, batches produced at diff erent times).

Randomisation was implemented with an internet-based system. Participants were stratifi ed by age: 65–74 years or 75 years or older. Within both age strata, the randomisation algorithm used a minimisation procedure accounting for study centre and whether participants lived in a retirement home. The study vaccines diff ered in terms of volume and presentation; therefore, unmasked personnel prepared and gave vaccines. The unmasked personnel did not participate further. Participants and individuals responsible for the assessment of any study endpoint were masked.

Procedures Participants received 0·7 mL AS03-adjuvanted TIV or 0·5 mL non-adjuvanted TIV (Fluarix; both manu-factured by GlaxoSmithKline, Rixensart, Belgium). The adjuvanted vaccine contained 5·93 mg α-tocopherol and 5·93 mg squalene in an oil-in-water emulsion (AS03B formulation). Both vaccines contained in-activated trivalent split virion antigens (15 μg haemagglutinin antigen per strain) as recommended by WHO. In both years, the infl uenza A antigens included in the vaccines were A/Brisbane/59/2007 (H1N1 strain) and A/Uruguay/716/2007 (H3N2 strain). In year 1, the infl uenza B strain was B/Brisbane/3/2007 (Yamagata lineage), and in year 2, B/Brisbane/60/2008-like (Victoria lineage). Vaccines were given intra-muscularly in the deltoid region of the non-dominant arm. Participants were scheduled to receive one vaccine in each year during the usual vaccination campaign, and remained in the same vaccine group in year 1 and year 2.

From Nov 15 to April 30 in both study years, participants were monitored by telephone or visits to study sites and home visits to identify cases of infl uenza-like illness, infl uenza-related complications, hospital admissions, and fatal outcomes. Between Dec 15 and March 31 (the expected peak season), contact was made every week; at other times, contact was made every 2 weeks. Participants reported symptoms of infl uenza-like illness (ie, passive surveillance). Nurses made visits to retirement homes every week. Cases of pneumonia and participants requiring admission or urgent care for respiratory disease were monitored by telephone, home visits, hospital visits, or site visits every week from Dec 15 to March 31, and every 2 weeks at other times. We recorded all deaths. An adjudication committee defi ned the infl uenza peak season in each year on the basis of national surveillance data and study data.

Infl uenza-like illness was defi ned as the simultaneous occurrence of at least one systemic symptom (headache, fatigue, myalgia, feverishness, or fever [oral temperature ≥37·5°C]) and at least one respiratory symptom (nasal congestion, sore throat, cough, dyspnoea, sputum production, or wheezing). After the onset of each suspected case, we obtained nasal and throat swabs within 24 h, or at least within 5 days. A case of infl uenza

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was confi rmed if the swab yielded RNA of infl uenza A or B virus, or both, by PCR. Clinical infl uenza was defi ned as infl uenza-like illness presenting with an oral temperature of at least 37·8°C and concurrent cough. A diagnosis of pneumonia was based on signs and symptoms and a chest radiograph showing a new or progressive infi ltrate, or was confi rmed by autopsy.

Swabs were stored at −70°C. After nucleic acid extraction, infl uenza RNA was amplifi ed and typed as infl uenza A or B as previously described.12 Cases of infl uenza A were subtyped into seasonal H1 and H3 through RT-PCR, with diff erent sets of primers targeting the haemagglutinin gene for H1 and H3 (appendix); some samples were not subtyped because they did not contain enough genetic material. We classifi ed cases of infl uenza B into B/Yamagata-like and B/Victoria-like lineages by ampli fi cation with primers targeting haemagglutinin (appendix), followed by sequencing. Samples positive for infl uenza A that were not subtyped by RT-PCR were processed by a commercially available multiplex reverse tran scriptase PCR (xTAG Respiratory Viral Panel, US IVD 96 tests; Luminex, Abbott Molecular, Ottignies-Louvain-la-Neuve, Belgium). Finally, we did a real-time RT-PCR of samples positive for infl uenza A that had not been subtyped to detect the H1 pandemic variant with primers and a probe targeting the matrix gene (appendix).

A subset of 6000 participants (reactogenicity and safety cohort; selected by the randomisation system) used diary cards to record the occurrence and intensity of solicited injection-site reactions (ec chymosis, pain, redness, and swelling) and solicited general adverse events (arthralgia, fatigue, gastro intestinal symptoms, headache, generalised myalgia, shivering, and fever) for 7 days after vaccination. We included 6000 participants in this cohort so that we would have safety data for 3000 individuals who received the AS03-adjuvanted TIV (ie, number required by regulatory authorities for assessment of safety). We assessed serious adverse events and potential immune-mediated diseases (pIMDs) in all participants throughout the study. A serious adverse event was defi ned as an event that resulted in death, was life-threatening, required hospital admission, prolonged existing hospital stay, or resulted in disability or incapacity. pIMDs included autoimmune diseases and neurological disorders, such as neurological or demyelinating events, rheumatic and connective diseases, infl ammatory bowel diseases, autoimmune endocrine diseases, autoimmune blood disorders, and infl ammatory skin disorders.

In the reactogenicity and safety cohort, we assessed solicited adverse events in the 7-day post-vaccination period, and unsolicited adverse events in the 21 days after vaccination. Add itionally, we assessed medically attended adverse events during the 21 days after vaccination and between 21 days and 180 days after vaccination in this subset. Unsolicited safety assess-

ments were made during visits to study centres or phone calls scheduled for day 21 (all unsolicited events), days 90 and 180 (medically attended adverse events, serious adverse events, and pIMDs), and days 270 and 365 (serious adverse events and pIMDs) in each year.

We divided adverse events, serious adverse events, and pIMDs into three groups on the basis of intensity: grade 1 (mild) events were easily tolerated, caused little

320 excluded from analysis 213 unmasked 12 vaccine not given according to protocol 32 not eligible 19 concomitant vaccines or other drugs 44 dropped out before surveillance

320 excluded from analysis 203 unmasked 3 vaccine not given according to protocol 37 not eligible 24 concomitant vaccines or other drugs 53 dropped out before surveillance

21 573 in year 1 efficacy cohort 21 482 in year 1 efficacy cohort

179 dropped out before peak season

145 dropped out before peak season

21 394 in year 1 peak-season efficacy cohort 21 337 in year 1 peak-season efficacy cohort

4731 did not receive vaccine in year 2 4273 not enrolled 458 enrolled but second dose not given

17 070 vaccinated with AS03-adjuvanted TIV in year 2

17 071 vaccinated with non-adjuvanted TIV in year 2

413 excluded from analysis 107 unmasked 97 vaccine not given according to protocol 23 not eligible 160 concomitant vaccines or other drugs 26 dropped out before surveillance

424 excluded from analysis 108 unmasked 95 vaccine not given according to protocol 24 not eligible 171 concomitant vaccines or other drugs 26 dropped out before surveillance

16 657 in year 2 efficacy cohort 16 647 in year 2 efficacy cohort

43 802 participants enrolled

43 695 underwent randomisation

107 withdrew, were not eligible, or did not receive vaccine

21 802 vaccinated with non-adjuvanted TIV in year 1

4823 did not receive vaccine in year 2 4335 not enrolled 488 enrolled but second dose not given

21 893 vaccinated with AS03-adjuvanted TIV in year 1

Figure 1: Trial profi leTIV=inactivated trivalent infl uenza vaccine.

See Online for appendix

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discomfort, and did not interfere with everyday activities; grade 2 (moderate) events were suffi ciently discomforting to interfere with everyday activities; grade 3 (severe) events impeded everyday activities. We coded all un solicited adverse events by preferred term and primary system organ class with the Medical Dictionary for Regulatory Activities (MedDRA). We deemed all solicited injection-site symptoms to be related to the vaccine; investigators provided causality assessments for solicited general symptoms and for adverse events, medically attended adverse events, serious adverse events, and pIMDs.

We had two coprimary objectives: to compare the effi cacy of one dose of AS03-adjuvanted TIV with that of non-adjuvanted TIV against seasonal infl uenza

during the surveillance period in year 1; and to establish lot-to-lot consistency of the AS03-adjuvanted TIV. Results for consistency will be reported elsewhere. The primary endpoint for the fi rst objective was the relative effi cacy of AS03-adjuvanted TIV versus the non-adjuvanted TIV for the prevention of infl uenza A or B, or both, in year 1, confi rmed by PCR analysis of viral RNA. Two secondary effi cacy endpoints compared the relative effi cacy of AS03-adjuvanted TIV versus non-adjuvanted TIV in years 1 and 2 combined: prevention of PCR-confi rmed infl uenza, and prevention of culture-confi rmed infl uenza. Because PCR-confi rmed infl uenza was assessed in the primary endpoint, we do not report data for culture-confi rmed infl uenza here. Three secondary effi cacy endpoints compared the relative effi cacy during the infl uenza peak season in year 1: prevention of pneumonia or clinical infl uenza, hospital admission for respiratory disease, and all-cause death. We assessed prevention of pneumonia post hoc. We did exploratory effi cacy analyses to assess the relative effi cacy of the two vaccines for the prevention of infl uenza by virus subtype during the surveillance period in year 1.

We obtained demographic and clinical information for all participants, including comorbidity index items and comorbidity status on the basis of the Charlson index.13 We also assessed the frequency and geographic dis tribution of vaccination against pandemic infl uenza in year 2.

Statistical analysesWe based calculations of sample size and statistical power on the assumption that the absolute effi cacy for AS03-adjuvanted TIV was 65% and for non-adjuvanted TIV was 50%.4,14 Our primary hypothesis was that the effi cacy of AS03-adjuvanted TIV would be 30% greater than that of non-adjuvanted TIV. We estimated that 43 614 participants were needed for 90% power to confi rm the relative vaccine effi cacy, with a one-sided α of 2·5%. With the assumption that the proportion of participants with detected infl uenza (ie, the attack rate) was 1·0% in the group given non-adjuvanted TIV, and that 10% of participants could not be assessed, at least 43 614 individuals would be needed to achieve 337 assessable cases of infl uenza. We would establish the superiority of AS03-adjuvanted TIV if the lower limit of the two-sided 95% CI for the relative effi cacy of AS03-TIV versus TIV was greater than zero. We did a futility analysis at the end of year 1 (appendix).

We described attack rates, relative effi cacy estimates for PCR-based endpoints, and clinical endpoints with two-sided 95% CIs. We estimated relative effi cacy and 95% CIs after fi tting a proportional hazards regression on the time-to-event curve, taking into account age and region (North America vs non-North America). The protocol stipulated that relative effi cacy estimates for all secondary endpoints were to be calculated with a 99% CI to maintain an overall type 1 error rate of 2·5%

AS03-adjuvanted TIV (n=21 893)

Non-adjuvanted TIV (n=21 802)

Age (years)

Mean (SD) 73·5 (6·1) 73·5 (6·2)

Median (range) 73 (60–102) 73 (61–104)

Age stratum

65–74 years 13 128 (60·0%) 13 052 (59·9%)

≥75 years 8765 (40·0%) 8750 (40·1%)

Sex

Male 9344 (42·7%) 9382 (43·0%)

Female 12 549 (57·3%) 12 420 (57·0%)

Seasonal infl uenza vaccine in previous 3 years

Yes 15 858 (72·4%) 15 760 (72·3%)

No 6034 (27·6%) 6042 (27·7%)

Comorbidity status*

Low or medium risk 19 545 (89·3%) 19 405 (89·0%)

High risk 2348 (10·7%) 2397 (11·0%)

Comorbidity index item

AIDS 7 (<0·1%) 5 (<0·1%)

Cerebrovascular disease 2410 (11·0%) 2438 (11·2%)

Chronic pulmonary disease 2190 (10·0%) 2116 (9·7%)

Congestive heart disease 3169 (14·5%) 3154 (14·5%)

Any connective-tissue disease 6051 (27·6%) 6099 (28·0%)

Dementia 346 (1·6%) 301 (1·4%)

Malignant neoplasm of lymphatic and haemopoietic tissue 83 (0·4%) 84 (0·4%)

Myocardial infarction 1458 (6·7%) 1489 (6·8%)

Peripheral vascular disease 1350 (6·2%) 1372 (6·3%)

Peptic ulcer disease 1452 (6·6%) 1432 (6·6%)

Diabetes mellitus with end-organ damage 1560 (7·1%) 1591 (7·3%)

Diabetes mellitus without organ damage 2884 (13·2%) 2817 (12·9%)

Moderate or severe liver disease 87 (0·4%) 84 (0·4%)

Moderate or severe renal disease 245 (1·1%) 265 (1·2%)

Non-metastatic malignant solid tumour 2256 (10·3%) 2243 (10·3%)

Metastatic malignant solid tumour 186 (0·8%) 205 (0·9%)

Data are n (%) unless otherwise stated. Comorbidity status and index items were based on the Charlson index.13 TIV=inactivated trivalent infl uenza vaccine. *Participants with a Charlson weighted comorbidity index score of <7 were described as having a low or medium comorbidity status, and those with a score of ≥7 were described as having a high comorbidity status.

Table 1: Baseline characteristics of the year 1 total vaccinated cohort

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for the primary and secondary endpoints. However, because the primary endpoint was not met, we deemed the secondary endpoints to be descriptive and calculated relative effi cacy estimates with 95% CIs. In the post-hoc analysis of pneumonia alone, the region covariate grouped countries according to the incidence of infl uenza cases in the group given the non-adjuvanted TIV: Netherlands, Poland, and Czech Republic; Belgium, UK, Norway, France, Germany, and Russia; or Canada, Romania, Mexico, Estonia, USA, and Taiwan.

We assessed baseline demographic and clinical charac teristics in all participants vaccinated in year 1 (total vaccinated cohort). The total vaccinated cohort in year 2 included all participants vaccinated in both years. We did effi cacy analyses during the surveillance period of individuals vaccinated in year 1 (year 1 effi cacy cohort). We assessed clinical endpoints in participants during the infl uenza peak season in year 1 (year 1 peak-season effi cacy cohort). The effi cacy analyses planned for year 2 were to include participants vaccinated in both years (year 2 effi cacy cohort). We did effi cacy analyses per protocol; we excluded participants with protocol viola tions, who fulfi lled exclusion criteria, or who dropped out before the start of a defi ned surveillance period.

Solicited adverse events, unsolicited adverse events, and medically attended adverse events were assessed in the reactogenicity and safety cohort. Serious adverse events and pIMDs were assessed in the total vaccinated cohort. We summarised reactogenicity and safety data with descriptive statistics and a two-sided 95% CI.

This trial is registered with ClinicalTrials.gov, number NCT00753272.

Role of the funding sourceThe sponsor designed the study, collected data, analysed data, interpreted data, and helped to write the report. All authors had full access to all the data in the study and

had fi nal responsibility for data analysis, data inter-pretation, and the decision to submit for publication.

Results43 695 participants were vaccinated in year 1 (fi gure 1). The mean age of participants was the same in both groups, and most participants had a comorbidity status of low or medium risk (table 1). The integrity of data from one site in Romania, where 102 participants were enrolled, came into question after completion of the study; an investigation done at the site identifi ed some irregularities in terms of compliance with good clinical practice. When we assessed the data from the Romanian site, we did not identify irregularities compared with overall study data; therefore, we included the data in analyses.

In the 2 years, 878 (4·0%) participants who received AS03-adjuvanted TIV in year 1 withdrew because of an adverse event or serious adverse event, as did 869 (4·0%) participants who received non-adjuvanted TIV in year 1. 3052 (17·9%) of 17 070 participants who received AS03-adjuvanted TIV and 3001 (17·6%) of 17 071 who received non-adjuvanted TIV again in year 2 received at least one dose of pandemic infl uenza vaccine (appendix).

590 cases of infl uenza-like illness were confi rmed as infection with infl uenza A or B, or both (one patient reported two infl uenza-like illnesses). When we excluded 2009 pan demic infl uenza A H1N1 strains, the attack rate was slightly lower in the group given AS03-adjuvanted TIV than in the group given non-adjuvanted TIV, but the lower limit of the 95% CI for relative effi cacy did not meet the predefi ned superiority criterion (table 2).

We took swabs as a result of fever in 189 (68·0%) of 278 participants in the group given AS03-adjuvanted TIV and 195 (62·5%) of 312 in the group given non-adjuvanted TIV who had PCR-confi rmed infl uenza (appendix). The probabilities that participants would not have a PCR-confi rmed case of infl uenza during the surveillance

Participants infected Relative effi cacy

AS03-adjuvanted TIV (n=21 573) Non-adjuvanted TIV (n=21 482)

Primary endpoint*

Infl uenza A or B, or both 274 (1·27%, 1·12 to 1·43) 310 (1·44%, 1·29 to 1·61) 12·11% (−3·40 to 25·29)

Exploratory analysis*†

Infl uenza A 224 (1·04%, 0·91 to 1·18) 270 (1·26%, 1·11 to 1·41) 17·53% (1·55 to 30·92)

Infl uenza A H3N2 170 (0·79%, 0·67 to 0·92) 205 (0·95%, 0·83 to 1·09) 17·54% (–1·05 to 32·71)

Infl uenza A H1N1 17 (0·08%, 0·05 to 0·13) 12 (0·06%, 0·03 to 0·10) −41·61% (−196·50 to 32·37)

Post-hoc analyses‡

Infl uenza A H3N2 190 (0·88%, 0·76 to 1·01) 242 (1·31%, 0·99 to 1·28) 22·0% (5·68 to 35·49)

Infl uenza B Yamagata 12 (0·06%, 0·03 to 0·10) 11 (0·05%, 0·03 to 0·09) −8·71% (−146·36 to 52·03)

Infl uenza B Victoria 37 (0·17%, 0·12 to 0·24) 29 (0·13%, 0·09 to 0·19) −27·16% (−106·75 to 21·80)

Data are n (%, 95% CI) or % (95% CI). Excluding A H1N1 pdm09 strains. TIV=inactivated trivalent infl uenza vaccine. *Real-time PCR. †No subtype was identifi ed with real-time PCR for 37 samples in the group given AS03-adjuvanted TIV and 53 samples in that given non-adjuvanted TIV; these samples were further analysed with multiplex RT-PCR. ‡Multiplex RT-PCR.

Table 2: Number of participants infected and relative effi cacy by infl uenza strain during the year 1 surveillance period in the year 1 effi cacy cohort

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period in year 1 seemed to be higher in the group given the AS03-adjuvanted TIV than in that given the non-adjuvanted TIV (fi gure 2), but the diff erence was not signifi cant (p=0·1205).

Most infections were due to infl uenza A (table 2). 91 (15·4%) cases of infl uenza-like illness were caused by infl uenza B strains (table 2), and fi ve (0·8%) by 2009 pan-demic virus. One patient who reported two infl uenza-like illnesses was infected with infl uenza A and infl uenza B separately. The dominant strain was infl uenza A H3N2 in all European countries; H3N2 and B strains were similarly dominant in Canada; B strains were dominant in Mexico and the USA; and seasonal H1N1 predominated in Taiwan (appendix). All fi ve cases of infection with pandemic H1N1 occurred in Mexico (appendix). The effi cacy of AS03-adjuvanted TIV was superior to that of the non-adjuvanted vaccine for infl uenza A and for infl uenza A H3N2 (table 2).

The circulation of the pandemic strain during year 2 resulted in low circulation of seasonal strains, which led to negligible attack rates (table 3). Therefore, we could not identify a peak season and we did not do the planned effi cacy analyses in year 2.

During infl uenza peak season in year 1, we recorded 172 cases of clinical infl uenza in each group. The frequency of pneumonia or clinical infl uenza was slightly lower in the group given AS03-adjuvanted TIV than in that given non-adjuvanted vaccine (table 4). The frequencies of all-cause death, hospital admission because of respiratory disease, and pneumonia only were

AS03-adjuvanted TIV (n=16 657)

Non-adjuvanted TIV (n=16 647)

Any seasonal infl uenza A or B, or both*

2 (0·01%, 0·00–0·04) 3 (0·02%, 0–0·05)

Infl uenza A* only 0 3 (0·02%, 0–0·05)

Infl uenza A H1N1* only 0 0

Infl uenza A H3N2 only 0 1 (0·01%, 0–0·03)

Infl uenza B only 2 (0·01%, 0–0·04) 0

Infl uenza A and B* 0 0

Pandemic Infl uenza A H1N1

31 (0·19%, 0·13–0·26) 28 (0·17, 0·11–0·24)

Data are n (%, 95% CI). Samples were assessed with real-time PCR. TIV=inactivated trivalent infl uenza vaccine. *Excluding infl uenza A H1N1 pdm09 strains.

Table 3: Number of participants infected by diff erent infl uenza strains during the year 2 surveillance period in the year 2 effi cacy cohort

AS03-adjuvanted TIV (n=21 394)

Non-adjuvanted TIV (n=21 337)

Relative effi cacy*

Pneumonia or clinical infl uenza

202 (0·94%, 0·82 to 1·08) 225 (1·05%, 0·92 to 1·20) 10·70% (−7·99 to 26·15)

All-cause death 63 (0·29%, 0·23 to 0·38) 88 (0·41%, 0·33 to 0·51) 28·59% (1·32 to 48·33)

Admission to hospital because of respiratory diseases

84 (0·39%, 0·31 to 0·49) 89 (0·42%, 0·34 to 0·51) 5·95% (−26·72 to 30·20)

Pneumonia only† 32 (0·15%, 0·10 to 0·21) 56 (0·26%, 0·20 to 0·34) 43·08% (12·13 to 63·14)

Data are n (%, 95% CI) or % (95% CI). TIV=inactivated trivalent infl uenza vaccine. *Descriptive estimates. †Post-hoc analysis with adjustment for regional diff erences in attack rates in the group given non-adjuvanted TIV.

Table 4: Clinical outcomes during peak season in year 1 in the year 1 peak season effi cacy cohort

98·5

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AS03-adjuvanted TIV (influenza A or B, or both)Non-adjuvanted TIV (influenza A or B, or both)AS03-adjuvanted TIV (influenza A H3N2)Non-adjuvanted TIV (influenza A H3N2)

Number at riskAS03-adjuvanted TIV

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20787

Figure 2: Kaplan-Meier survival curves for any PCR-confi rmed case of infl uenza A or B, or both, and for any case of infl uenza A H3N2 during the year 1 surveillance periodTIV=inactivated trivalent infl uenza vaccine.

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also lower in the group given AS03-adjuvanted TIV than in that given non-adjuvanted TIV (table 4).

During the 7 days after vaccination in the reactogenicity and safety cohort in year 1, pain was the most frequent solicited injection-site symptom (fi gure 3): 1225 (41·0%) of 2988 participants who completed diary cards for pain and other local symptoms given AS03-adjuvanted TIV (four grade 3) and 477 (16·1%) of 2968 given non-adjuvanted TIV (three grade 3) reported pain. The most frequent solicited general symptom was fatigue (fi gure 3): 646 (21·6%) of 2986 given AS03-adjuvanted TIV who completed the relevant diary cards and 417 (14·0%) of 2968 given non-adjuvanted TIV reported fatigue. We recorded only one case of grade 4 fever (>40·0°C) in the group given the AS03-adjuvanted TIV; grade 3 solicited general symptoms were generally uncommon overall (fi gure 3). Solicited symptoms after the second vac cination in year 2 were consistent with those reported in year 1 (appendix).

In year 1, 855 (14·2%) of the 6017 participants in the reactogenicity and safety cohort reported at least one unsolicited adverse event in the 21-day post-vaccination period (table 5). The most common adverse events in this period in both groups were nasopharyngitis (33 [1·1%] of 3015 given AS03-adjuvanted TIV; 33 [1·1%] of 3002 given non-adjuvanted TIV), and cough and upper-respiratory-tract infection (29 [1·0%]; 28 [0·9%]). In year 1, medically attended adverse events were reported by a slightly higher proportion of participants in the group given AS03-adjuvanted TIV than in that given non-adjuvanted TIV in the period until day 179 post vaccination (table 5). In year 2, 626 (12·6%) of 4982 participants in the reactogenicity and safety cohort reported at least one unsolicited adverse event in the 21 days after vaccination (table 5). Again, medically attended adverse events were reported by a slightly higher proportion of participants in the group given AS03-adjuvanted TIV than in that given non-adjuvanted TIV (table 5).

At least one serious adverse event was reported in the 365 days after vaccination by 4071 (18·6%) of 21 893 participants given AS03-adjuvanted TIV and 4066 (18·6%) of 21 802 given non-adjuvanted TIV. The investigator deemed that nine of these events in the group given AS03-adjuvanted TIV and six in that given non-adjuvanted TIV were vaccine-related. The most frequent serious adverse events (classifi ed by MedDRA preferred terms) were pneumonia (228 [1·0%] of 21 893 given AS03-adjuvanted TIV; 226 [1·0%] of 21 802 given non-adjuvanted TIV), atrial fi brillation (211 [1·0%]; 178 [0·8%]), cerebro vascular accident (196 [0·9%]; 180 [0·8%]), and myocardial infarction (169 [0·8%]; 167 [0·8%]). 768 (3·5%) participants given AS03-adjuvanted TIV and 779 (3·6%) given non-adjuvanted TIV had fatal serious adverse events; none were judged to be related to the vaccines.

103 (0·5%) participants given AS03-adjuvanted TIV and 99 (0·5%) given non-adjuvanted TIV reported

pIMDs (appendix). In the group given AS03-adjuvanted TIV, 13 (0·1%) participants reported pIMDs that were deemed to be vaccine-related, of which three were grade 3 (rheumatoid arthritis, axonal neuropathy, and Miller Fisher syndrome [subclass of Guillain-Barré syndrome]). In the group given non-adjuvanted TIV, seven (<0·1%) participants reported pIMDs that were deemed to be vaccine-related, of which one was grade 3 (polymyalgia rheumatica). Of the 13 participants given AS03-adjuvanted TIV who had vaccine-related pIMDs, four had recovered at the time of analysis, three were

Solicited injection-site symptoms

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AS03-adjuvanted TIV (n=2988)Non-adjuvanted TIV (n=2968)

AS03-adjuvanted TIV (n=2986)Non-adjuvanted TIV (n=2968)

Figure 3: Reactogenicity during the 7 days after vaccination in year 1 in the reactogenicity and safety cohort(A) Solicited injection-site symptoms. (B) Solicited general symptoms. Analysis includes all participants in the reactogenicity and safety cohort who were vaccinated in year 1 and who returned diary cards. Error bars show 95% CI. TIV=inactivated trivalent infl uenza vaccine.

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recovering, and six were not recovered; of the seven given non-adjuvanted TIV, one had recovered, one was recovering, and fi ve were not recovered. We recorded two cases of Guillain-Barré syndrome (one Miller Fisher syndrome) in the group given AS03-adjuvanted TIV that were judged to be vaccine-related, and two cases in the group given non-adjuvanted TIV that were judged not to be vaccine-related.

DiscussionWe have shown that an AS03-adjuvanted TIV is not superior to a non-adjuvanted TIV for the prevention of infl uenza in people aged 65 years or older (panel). Our study suggests that the benefi t of infl uenza vaccination in elderly people might vary depending on infl uenza subtypes; we recorded the greatest effi cacy against infl u-enza A H3N2. Additionally, we showed a benefi t of adju-vanted vaccine versus standard care for prevention of death and pneumonia. Although fi ndings for our primary endpoint were not signifi cant, our trial had 43 000 elderly participants in stable health and provides valuable lessons for assessment of new infl uenza vaccines in this population.

When we designed the primary endpoint, we implicitly accepted that severity of clinical breakthrough infection would be similar irrespective of type of infl uenza infection, and we also assumed that the eff ect of the

vaccine candidate would be equal against circulating infl uenza A subtypes and infl uenza B lineages. In retrospect, these assumptions are questionable. First, in elderly people, infl u enza A H3N2 poses a higher risk of complications and death than do strains of infl uenza B or infl uenza A H1N1.1,2,17 The highest attack rates during year 1 were reported in countries where infl uenza A H3N2 was the dominant circulating strain; overall, infl uenza-like illness was most frequently associated with this strain. Second, B strains belonging to two distinct lineages (Yamagata-like and Victoria-like) circulate during the same season. Because there is little previous evidence of cross-lineage protection, TIVs containing only one lineage cannot be assumed to off er equivalent protection against both lineages. During year 1, the recommended B strain antigen for the northern hemisphere was from the Yamagata lineage, and both B lineages were detected.

Although the relative effi cacy for prevention of infl uenza A or B, or both, was not signifi cant according to our prespecifi ed endpoint, our fi ndings do not mean that the AS03-adjuvanted TIV had no benefi t, because even a modest increase in protection could be important in a vulnerable elderly population. Indeed, because the 12% increase is relative to an existing TIV, this effi cacy represents additional protection to that off ered by the standard of care. Furthermore, the increase in protection

AS03-adjuvanted TIV Non-adjuvanted TIV

Year 1 (n=3015) Year 2 (n=2462) Year 1 (n=3002) Year 2 (n=2520)

Adverse events (days 0–20)

Participants with ≥1 event 428 (14·2%) 320 (13·0%) 427 (14·2%) 306 (12·1%)

Participants with ≥1 grade 3 event 48 (1·6%) 36 (1·5%) 52 (1·7%) 26 (1·0%)

Participants with ≥1 event related to vaccination* 83 (2·8%) 42 (1·7%) 58 (1·9%) 20 (0·8%)

Number of events (MedDRA preferred terms)† 592 432 604 392

Number of grade 3 events (MedDRA preferred terms)† 58 46 64 31

Number of grade 3 events related to vaccination (MedDRA preferred terms)* 9 59 5 25

Medically attended adverse events (days 0–20)

Participants with ≥1 event 186 (6·2%) 179 (7·3%) 169 (5·6%) 168 (6·7%)

Participants with ≥1 grade 3 event 35 (1·2%) 29 (1·2%) 43 (1·4%) 22 (0·9%)

Participants with ≥1 event related to vaccination* 13 (0·4%) 6 (0·2%) 7 (0·2%) 5 (0·2%)

Number of symptoms (MedDRA preferred terms)† 227 226 210 210

Number of grade 3 events (MedDRA preferred terms)† 41 34 53 27

Number of grade 3 events related to vaccination (MedDRA preferred terms)* 15 2 10 1

Medically attended adverse events (days 21–179)

Participants with ≥1 event 912 (30·2%) 757 (30·7%) 893 (29·7%) 781 (31·0%)

Participants with ≥1 grade 3 event 197 (6·5%) 140 (5·7%) 174 (5·8%) 137 (5·4%)

Participants with ≥1 event related to vaccination* 4 (0·1%) 1 (<0·1%) 0 0

Number of symptoms (MedDRA preferred terms)† 1528 1182 1437 1235

Number of grade 3 events (MedDRA preferred terms)† 273 175 225 182

Number of grade 3 events related to vaccination (MedDRA preferred terms)* 0 0 0 0

TIV=inactivated trivalent infl uenza vaccine. MedDRA=Medical Dictionary for Regulatory Activities. *On the basis of investigators’ assessment of causality. †Symptoms reported by participant after a dose; the same preferred term was counted once.

Table 5: Unsolicited adverse events and medically attended adverse events in years 1 and 2 in the reactogenicity and safety cohort

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against infl uenza A H3N2 might be clinically important in view of the risk that this strain poses to elderly people.1,2,17 Moreover, the low incidence of breakthrough infl uenza A H1N1 and B infection, and the fact that more than 70% of participants had received seasonal infl uenza vaccine during the previous three infl uenza seasons, suggests that a combination of prevaccination immunity and post vaccination boosting is suffi cient to minimise the risk of infection with these strains. Therefore, on the basis of the weakness of the composite primary endpoint to establish signifi cant relative effi cacy, and in view of the results of the subtype analyses, we recommend that future infl uenza vaccine studies in elderly people should be based on virus subtype or lineage-specifi c endpoints, specifi cally pre-vention of infl uenza A H3N2. To accrue suffi cient participants to account for annual variations in infl uenza subtypes, sequential cohorts should be enrolled in several seasons.

The aim of infl uenza vaccination in elderly people is to reduce risk of severe infl uenza-related complications, such as pneumonia, myocardial infarction, congestive heart failure, stroke, and death. In our study, the incidence of all-cause death during peak season in year 1 was signifi cantly lower in the group given AS03-adjuvanted TIV than in that given non-adjuvanted TIV. In the post-hoc analysis, pneumonia only was also signifi cantly reduced. However, although we obtained nasal or pharyngeal swabs to test for infl uenza virus RNA in participants reporting infl uenza-like illness, swabs were not obtained from most participants with pneumonia or those who died during the peak infl uenza season. Only 18 (20·5%) of 88 participants with pneu monia were swabbed, of whom only three were positive for infl uenza RNA. Similarly, only eight (5·3%) of 151 participants who died from any cause were swabbed, of which one was positive for infl uenza RNA.

To prospectively sample participants with pneumonia or those with other suspected infl uenza-related com-plications is operationally challenging because indi-viduals with severe outcomes might not experience infl uenza-like illness or their progression from infection to hospital admission could be rapid. Additionally, death can be quick and occur before a swab can be obtained. Although establishment of an improvement in infl uenza-related complications is important from a clinical perspective, regulators and funders are likely to request evidence of protection against confi rmed infl uenza to justify invest ment in an alternative vaccine approach. Without viral analysis, clinical outcomes cannot be linked to infl uenza infection; however, we estimate that a sample of more than 100 000 individuals would be necessary to show relative effi cacy with a PCR-confi rmed clinical endpoint in a community-dwelling elderly population on the basis of previous reports.1,3,18–20 To assess vaccine effi cacy

against hospital admission and death due to confi rmed infl uenza would be more feasible in high-risk elderly populations, such as frail individuals or those living in care facilities. However, from a public health perspective, assessment of the benefi ts of a new vaccine would be most relevant in a population representing most elderly people who are recom-mended for seasonal vaccination—ie, ambula tory people in retirement homes or those who are community-based.

Panel: Research in context

Systematic reviewThe Cochrane Collaboration did a systematic review in 2005,5 with an update in 2009,6 to assess the evidence for effi cacy, eff ectiveness, and safety of infl uenza vaccines in people aged 65 years or more. The review included 75 studies, of which only fi ve were randomised controlled trials. On the basis of a meta-analysis of two of these trials, inactivated vaccine was shown to be more eff ective than was placebo against infl uenza-like illness in community-dwelling individuals during periods of high viral circulation. However, because annual infl uenza vaccination is recommended for people older than 65 years, the use of a placebo is now deemed to be unethical in elderly people; the last placebo-controlled vaccine effi cacy trial in this population was done 20 years ago.15 The Cochrane Collaboration review5,6 was based mainly on observational studies, and suggested that the best eff ectiveness for vaccination is reported for infl uenza-related complications in people in long-term care facilities, and the worst for infl uenza or pneumonia in community-dwelling people. However, in the 2009 update,6 Jeff erson and colleagues concluded that “any conclusions regarding the eff ects of infl uenza vaccines for people aged 65 years or older cannot be drawn” because of the poor quality of evidence. To identify studies done after the Cochrane reviews, we searched Medline for reports published in English between Sept 1, 2009, and July 1, 2012, with the search terms “elderly”, “65 years”, “seasonal”, “infl uenza”, and “vaccine”. We identifi ed no studies of effi cacy or eff ectiveness estimates of seasonal infl uenza vaccines in people aged 65 years and older. In 2012, Osterholm and colleagues did a systematic review16 to assess the effi cacy and eff ectiveness of infl uenza vaccines in trials with PCR-confi rmed or culture-confi rmed endpoints of infl uenza, but did not identify studies in populations aged 65 years or older.

InterpretationBecause few studies have assessed infl uenza vaccine effi cacy and eff ectiveness in elderly populations, with available data of poor quality, our study represents an important addition to the evidence base. As far as we are aware, ours is the largest randomised trial of infl uenza vaccine in elderly people. Infl uenza vaccination is most often assessed in frail people and those in care homes, but we enrolled only ambulatory elderly people who were community-based or lived in a retirement home and could mix with the community. We have shown that an AS03-adjuvanted inactivated trivalent infl uenza vaccine has a 12% higher effi cacy than does a non-adjuvanted vaccine for the prevention of infl uenza A or B, or both, but this diff erence was not signifi cant. Nevertheless, we believe ours is the fi rst effi cacy estimate of adjuvanted vaccine versus standard of care in an elderly population. Epidemiological data show that infl uenza A H3N2 is clinically more important than are infl uenza A H1N1 and infl uenza B in elderly people, and our study suggests that the benefi t of infl uenza vaccination in elderly people might vary depending on infl uenza subtypes, with the greatest effi cacy against infl uenza A H3N2. Finally, we showed a benefi t of adjuvanted vaccine versus standard of care for the prevention of death and pneumonia.

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In view of the challenges of randomised trials in elderly populations, prospective, observational studies with a test-negative case-control design are needed to assess the eff ectiveness of existing TIVs for prevention of severe outcomes in these individuals before other large-scale trials of new vaccines begin. In a test-negative case-control approach, vaccination histories of indi viduals with acute respiratory illness who test positive for infl uenza virus are compared with those of individuals without confi rmed infl uenza infection (test-negative controls). This method provides a highly sensitive and specifi c measure of vaccine eff ectiveness in populations with high attack rates of infl uenza-like and non-infl uenza-like illnesses, and has been used to assess seasonal infl uenza vaccine eff ectiveness in elderly people.15,21–23 In a small-scale study of community-dwelling people older than 50 years who were admitted to hospital for respiratory symptoms in three sequential infl uenza seasons,15 14 (36%) of 39 individuals positive for infl uenza and 250 (66%) of 378 negative for infl uenza were vaccinated, giving an unadjusted vaccine eff ectiveness of 71·3%. In another study of people with medically attended acute respiratory illness during the 2010–11 infl uenza season in the USA,22 191 infl uenza-positive cases and 833 infl uenza-negative cases were reported in individuals aged 50 years or older, corres ponding to vaccine eff ectiveness of 52% against in fl uenza A H3N2, 45% against infl uenza A H1N1, and 47% against infl uenza B. We suggest that studies that are similar but done on a larger scale than previously are needed before further randomised trials of new vaccines are done in community-based elderly populations.

The immunogenicity analyses from this trial will be reported elsewhere, including a post-hoc analysis of the association between infl uenza A H3N2 attack rates and vaccine-induced A H3N2 antibody titres. Briefl y, 21 days after vaccination in year 1, haemagglutination-based antibody responses were stronger in the group given AS03-adjuvanted TIV than in that given non-adjuvanted TIV. Although our study supports the notion that enhanced immunogenicity with AS03-adjuvantation results in reduced rates of infection and improved clinical out comes, the primary vaccine effi cacy analysis suggests that the benefi t of AS03-adjuvantation could be modest in elderly people. A TIV formulated with the oil-in-water adjuvant MF59 is licensed and widely used in elderly people, and, although it has signifi cantly better immunogenicity than does non-adjuvanted infl uenza vaccine,24 no prospective, randomised clinical trials of vaccine effi cacy of this formulation have been done in people aged 65 years or older. Therefore, the benefi ts of adjuvantation of seasonal infl uenza vaccines for the prevention of infl uenza infection and related com-plications in this vulnerable population remain to be established.

The benefi ts of infl uenza vaccination are generally believed to outweigh the risks, but oil-in-water adjuvants might induce autoimmunity.25,26 As such, regulatory authorities have recommended monitoring of specifi c neurological and autoimmune events, and have provided guidance for use of MedDRA preferred terms to identify pIMD reports.27 Additionally, monitoring of Guillain-Barré syndrome after infl uenza vaccination became a priority after an increased number of cases was reported after vaccination against pandemic infl uenza in the 1970s.28,29 Although our trial was not powered to assess rare events, it provided the opportunity to describe the safety of an AS03-adjuvanted vaccine in participants under active surveillance for pIMDs.

In the 2 year study, 0·5% of participants in both vaccine groups reported at least one pIMD. The most frequent pIMDs were polymyalgia rheumatica and rheumatoid arthritis. However, polymyalgia rheumatica is common in elderly people,30,31 and the overall fre-quency in our study was low. We recorded two cases of Guillain-Barré syndrome in both groups. In a report based on epidemiological data from 1980–2008, the annual background incidence of this disorder in individuals older than 50 years was estimated at 3·3 cases per 100 000 people.32 Therefore, the incidence of Guillain-Barré syndrome in our study seems to be slightly raised in both vaccine groups, although whether the cases were related to vaccination is unknown. More than 18% of participants reported at least one serious adverse event in both vaccine groups, which were most frequently pneumonia, atrial fi brillation, cerebrovascular accident, and myocardial infarction. Overall, our results suggest that the safety profi le of the adjuvanted vaccine was clinically acceptable.

ContributorsJEM, JB, J-MD, GMR-P, GAvE, CD, MEI, S-JH, BLI, AN, AT, and LO

participated in study design. JEM reviewed the medical literature,

participated in data analysis and chaired the publication steering

committee. JEM, JB, J-MD, ME, OL, GL-R, GMR-P, GAvE, AC, CC,

CD, XD, MEI, S-JH, BLI, MK, SM, and LO interpreted data. JEM, JB,

J-MD, ME, GL-R, GMR-P, AC, CC, GF, S-JH, BLI, MK, PK, SM, AT,

and LO supervised the study. JB, J-MD, ME, OL, GL-R, GMR-P, GAvE,

AC, CC, CD, XD, MEI, GF, FG, S-JH, MK, PK, SM, AN, JHR, AT, and

LO collected and assembled data. JB, JM-D, ME, GL-R, GMR-P, GAvE,

CD, MEI, S-JH, and LO generated data. CD and MEI designed

statistical analyses. JEM, JB, J-MD, ME, OL, GL-R, GMR-P, GAvE,

S-JH, BLI, and LO drafted and wrote the report. All authors reviewed

the report during its development and approved its fi nal version. JEM,

JB, J-MD, ME, OL, GL-R, GMR-P, GAvE, and LO are the members of

the publication steering committee and core writing team.

The Infl uence65 study groupPrincipal investigators: P-H Arnould, Y Balthazar, A-H Batens,

H Coppens, M De Meulemeester, P De Witte, L Devriendt, G Henry,

G Leroux-Roels, G Mathot, O Maury, P Muylaert, A Renson, P Soetaert,

L Tilley, D Van Riet, S Vanden Bemden (Belgium); N Aggarwal,

F Blouin, M Ferguson, J-S Gauthier, B Lasko, J McElhaney, S McNeil,

C Powell, P Rheault, D Shu, E St-Amour (Canada); J Beran,

V Chocensky (Czech Republic); I Koort, K Maasalu, A Poder,

L Randvee, S Rosenthal, M Stern, J Talli (Estonia); R Arnou,

C Bortolotti, J-P Boyes, C Dubray, X Duval, R Ferrier, C Fivel,

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J-F Foucault, F Galtier, P Igigabel, O Launay, D Saillard, C Scellier,

J Tondut, P Uge (France); E Beck, A Benedix, B Bergtholdt,

F Burkhardt, A Colberg, A Dahmen, R Deckelmann, H Dietrich,

R Dominicus, T Drescher, T Eckermann, U Elefant, M Esen,

G Fahron, S Fischer, K Foerster, H Folesky, M Frick, U Gehling,

M Golygowski, C Grigat, A Himpel-Boenninghoff , P Hoeschele,

S Höltz, B Huber, S Ilg, G Illies, J-P Jansen, F Kaessner, D Kieninger,

C Klein, U Kleinecke-Pohl, A Kluge, W Kratschmann, K H Krause,

J Kropp, A Langenbrink, R Lehmann, A Linnhoff , A Markendorf,

S Maxeiner, G Meissner, I Meyer, B Moeckesch, M Mueller, S Mueller,

G Neumann, C Paschen, G Plassmann, H-H Ponitz, A Preusche,

A Rinke, H Samer, T Schaberg, F Schaper, I Schenkenberger,

J Schmidt, B Schmitt, H Schneider, M Schumacher, T Schwarz,

H-D Stahl, K Steinbach, U Steinhauser, J Stockhausen, B Stolz,

N Toursarkissian, K Tyler, J Wachter, H G Weber, K Weyland, D Wolf,

K Zitzmann (Germany); C Aranza Doniz, M L Guerrero,

E Lazcano-Ponce, A Mascareñas de Los Santos, N Pavia-Ruz,

G M Ruiz-Palacios (Mexico); G A van Essen, J H Richardus, H Rumke

(Netherlands); S Elle, A Holmberg, H O Høivik, T Kjærnli, P Norheim,

A Tandberg (Norway); W Gadzinski, J Holda, E Jazwinska-Tarnawska,

T Lepich, R Lysek, H Nowakowska, M Orzechowska, Z Szumlanska

(Poland); A Abaitancei, C Oproiu, S Orban, F Vasilache, D Toma

(Romania); I Osipova, O Perminova, V Romanenko, V Semerikov

(Russia); S-J Hwang, P-C Yang (Taiwan); E Abdulhakim, I Pavel-Knox,

A Raja, H Shaw (UK); M Blatter, D Boos, B Bowling, S Bowman,

D Brune, S Christensen, T Christensen, L Civitarese, H J Downey,

H Durrence, H El Sahly, J Earl, J Ervin, B Essink, A R Falsey,

G Feldman, T Fiel, C Fogarty, S Folkerth, S E Frey, D Fried, G Gibson,

M Hall, W Harper, S Hull, J Jacobson, J Jacqmein, J Lawless,

C Lucasti, R Middleton, S Plunkett, T Poling, G Raad, G Ramsbottom,

K Reisinger, E Riff er, J Rosen, E Ross, J Rubino, S Sperber,

H Studdard, J Thrasher, M Turner, M Van Cleeff , L Wadsworth,

J Yakish (USA). GlaxoSmithKline Vaccines Clinical Study Support: A Caplanusi, C Claeys, J-M Devaster, B Innis, M Kovac, L Oostvogels,

C Van Der Zee. Laboratory partners: F Allard, S Durviaux, N Houard,

T Ollinger, K Walravens. Statistical analysis partners: W Dewé,

C Durand, M El Idrissi, M Oujaa. Members of the independent data monitoring committee: J Claassen, A Grau, R Konior (chair), F Verheugt.

Members of the adjudication committee: M Betancourt-Cravioto,

D Fleming, K Nichol, W J Paget (chair).

Confl icts of interestJEM, JB, ME, OL, GL-R, GMR-P, GAvE, XD, ARF, FG, AN, and JHR have

received honoraria or travel grants, or provided paid expert testimony

from the GlaxoSmithKline group of companies. JEM has received

honoraria for participating in advisory boards (not related to this trial)

from the GlaxoSmithKline group of companies, Abbott Pharmaceuticals,

MedImmune, Novartis, and Sanofi Pasteur. J-MD, AC, CC, CD, MEI,

BLI, MK, AT, and LO are employees of the GlaxoSmithKline group of

companies. J-MD, AC, CC, BLI, MK, AT, and LO own stock options for

the GlaxoSmithKline group of companies. SM has received a research

grant from the GlaxoSmithKline group of companies. GF, S-JH, and PK

declare that they have no confl icts of interest.

AcknowledgmentsGlaxoSmithKline Biologicals SA funded the trial, was involved in all

stages of the study conduct and analysis, and paid all costs associated with

the development of this report. We thank the study volunteers;

participating clinicians, nurses, and laboratory technicians at the study

sites; the sponsor’s project staff for their support and contributions

throughout the study; and Dirk Züchner for his contribution to the study.

We thank the GSK Biologicals SA team: Mathieu Albanese, Natassia

Della-Vecchia, Marcel Dupelle, Stéphanie Fannoy, Thomas Hennekinne,

Nathalie Houard, Nathalie Légaré, Marie-Pier Tonietto, Laurence Pesche,

Magali Ribot, Annie Senneville, and Valérie Wansard for their

participation in clinical testing; Sandie Marion (4 Clinics, Belgium, on

behalf of GSK Biologicals SA) for her participation in data analysis; and

Laurence Baufays, Vincent Dodeur, Laurence Hollinger, Karolien Peeters

(freelance, Spain, on behalf of GSK Biologicals SA), and Wendy Talbott for

their involvement in the study coordination and study management. We

also thank Annick Moon (Moon Medical Communications, UK) and

Miriam Hynes (freelance writer, UK) who provided medical writing

services on behalf of GlaxoSmithKline Biologicals SA; Isabelle Camby and

Géraldine Drevon (GlaxoSmithKline Biologicals SA), Stéphanie Delval,

and Wendy Van Doorslaer (XPE Pharma and Science, on behalf of

GlaxoSmithKline Biologicals SA) for publication coordination and

management and making sure that recommendations from the

International Committee of Medical Journal Editors were fulfi lled.

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