Rotavirus in Queensland, 2006-2017

Communicable Diseases Branch

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 1 -

Rotavirus in Queensland

Published by the State of Queensland (Queensland Health), September 2017

This document is licensed under a Creative Commons Attribution 3.0 Australia licence.

To view a copy of this licence, visit creativecommons.org/licenses/by/3.0/au

© State of Queensland (Queensland Health) 2017

You are free to copy, communicate and adapt the work, as long as you attribute the

State of Queensland (Queensland Health).

For more information contact:

Communicable Diseases Branch, Department of Health, GPO Box 48, Brisbane QLD

4001, email epi@health.qld.gov.au, phone 07 3328 9728.

An electronic version of this document is available at

https://www.health.qld.gov.au/clinical-practice/guidelines-procedures/diseases-

infection/surveillance/reports/vaccine-preventable

Disclaimer:

The content presented in this publication is distributed by the Queensland Government as an information source only.

The State of Queensland makes no statements, representations or warranties about the accuracy, completeness or

reliability of any information contained in this publication. The State of Queensland disclaims all responsibility and all

liability (including without limitation for liability in negligence) for all expenses, losses, damages and costs you might

incur as a result of the information being inaccurate or incomplete in any way, and for any reason reliance was placed

on such information.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 2 -

Contents

Summary ............................................................................................................ 3

Introduction......................................................................................................... 4

Method ............................................................................................................... 5

Results ............................................................................................................... 7

Rotavirus notifications in Queensland 2006-2017 ................................................ 7

Vaccination information for children younger than one year notified with

rotavirus in Queensland 2008-2015 ................................................................... 11

Rotavirus Vaccination coverage ......................................................................... 12

Rotavirus testing in Queensland public laboratories 2006-2017 ......................... 12

Other surveillance systems ................................................................................ 13

References ....................................................................................................... 14

Figures

Figure 1 Number of notifications of rotavirus in Queensland by year and quarter of

onset, 2006- Q2 2017. .................................................................................................. 7

Figure 2 Rates of rotavirus notifications in Queensland by age group per 100,000

population per year, 2006-30 June 2017 ....................................................................... 8

Figure 3 Proportion of positive public laboratory tests for rotavirus in Queensland by

test type and age group, 2006-Q1 2017 ...................................................................... 13

Tables

Table 1 Number of notifications for Queensland Hospital and Health Services, 2006-30

June 2017. .................................................................................................................... 9

Table 2 Rates of rotavirus notifications for Queensland Hospital and Health Services

per 100,000 population per year, 2006-30 June 2017. ................................................ 10

Table 3 Vaccine doses recorded for children younger than one year notified with

rotavirus, Queensland, 2008-2015. ............................................................................. 11

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 3 -

Summary

Over an 11.5 year period (from 1 January 2006 until 30 June 2017) a total of 14186

confirmed rotavirus cases were notified in Queensland. Notification has shown a

substantial decline from 2006 to 2007 following commencement of the vaccination

program in July 2007.

The average crude rate of notification in Queensland from 2007-2016 is 24 (range 18-

31) notifications per 100,000 population per year which is half the rate recorded in 2006

of 62 notifications per 100,000 population per year.

Since the decline in 2007, the pattern of notifications in Queensland shows a regular

peak in late winter and spring.

The greatest burden of rotavirus infection is seen in children younger than one year of

age with the highest number and rates of notifications. This is consistent with the

epidemiology of rotavirus seen in Australia and across the world.

Laboratory testing issues for rotavirus have impacted on the pattern of notifications. A

commercial rotavirus immunochromatographic test used in Queensland laboratories

was shown to have low specificity during 2011-2013. (1, 2) This is likely to have

translated into false positive notifications of disease.

The introduction of PCR testing in late 2015 has resulted in a peak in notifications of

children younger than one year of age. As the current PCR assays do not discriminate

between vaccine and wild type virus it is likely to be detecting rotavirus in recently

vaccinated children with co-incidental gastroenteritis or gastrointestinal symptoms.

There has been a marked improvement in the capture of Indigenous status for rotavirus

notifications due to electronic linkage with vaccination records in Queensland. This

improvement will assist in determining the impact of vaccination on the high burden of

severe rotavirus infection seen in Aboriginal and/or Torres Strait Islander children prior

to vaccination. (3)

There are plans to make rotavirus nationally notifiable, therefore no national data for

comparison with Queensland data over the period of this report are currently available.

However, a number of reports using hospitalisation, notification, and laboratory data

from Australian jurisdictions provide evidence of a substantial decline in rotavirus

infection as a result of the rotavirus vaccination program.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 4 -

Introduction

Rotavirus infection can cause severe viral gastroenteritis in infants and children. Prior

to vaccination becoming available in Australia, rotavirus caused up to half of all

hospitalised cases of gastroenteritis in children younger than five years of age. (3)

Rotavirus became notifiable in Queensland in 2005 through laboratories and there is a

proposal that it become a nationally notifiable condition in 2017.

Vaccines for rotavirus first became available in Australia in early 2006 and were added

to the National Immunisation Program from 1 July 2007. At this time, Queensland

began vaccinating children with RotaTeq (Merck/Seqirus) in a 3-dose schedule

administered orally at 2, 4, and 6 months of age.

Since vaccines have been available in Australia, there have been a number of reports

showing a decrease in rotavirus infections using laboratory testing, notification, and

hospitalisation data. These indicate a decrease in age-groups at high risk of rotavirus

and a concurrent decrease in older age groups where herd immunity plays a role. (4-6)

There are changes being made to rotavirus vaccination in the National Immunisation

Program. From 1 July 2017 Queensland will be replacing the 3 dose RotaTeq schedule

with a 2 dose Rotarix (GSK) schedule. Rotarix will then become the sole rotavirus

vaccine being used in the National Immunisation Program.

In this report we have summarised the epidemiology of rotavirus in Queensland since

2006 by:

describing the trends in rotavirus notifications in Queensland since 2006,

particularly those received in children younger than one year, and

exploring the trends in laboratory testing data for rotavirus testing performed

in public laboratories in Queensland.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 5 -

Method

Rotavirus is a notifiable condition on pathological diagnosis under the Queensland

Public Health Regulation 2005. Pathology providers are required to notify the

Department of Health of any positive tests for rotavirus. Cases notified during 2006-

2016 are classified as per the Queensland case definition for rotavirus (see Box 1) for

confirmed (valid) cases. It has been proposed that Rotavirus become a nationally

notifiable condition in 2017. In preparation for this, Queensland introduced a case

definition for probable and confirmed cases from the beginning of 2017 (see Box 2).

Box 1 Queensland Rotavirus case definition 2006-2016

Confirmed case

A confirmed case requires laboratory definitive evidence.

Laboratory definitive evidence

Detection of rotavirus by antigen assay OR

Detection of rotavirus by nucleic acid testing OR

Detection of rotavirus by electron microscopy OR

Isolation of rotavirus.

Box 2 New Rotavirus case definition 2017

Confirmed case

A confirmed case requires either:

1. laboratory definitive evidence

OR

2. laboratory suggestive evidence AND epidemiological evidence.

Laboratory definitive evidence

Detection of wild-type rotavirus by nucleic acid testing*

Laboratory suggestive evidence

1. Detection of rotavirus by antigen assay OR

2. Detection of rotavirus by nucleic acid testing OR

3. Detection of rotavirus by electron microscopy OR

4. Isolation of rotavirus

Epidemiological evidence

The case is older than 8 months of age OR

The case that has not been vaccinated in the 4 weeks prior to testing.

Probable case

A probable case requires laboratory suggestive evidence only.

*detection of rotavirus by nucleic acid testing that does not distinguish between wild-

type and vaccine-related virus is suggestive laboratory evidence

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 6 -

A confirmatory laboratory result generates an electronic notification to the Notifiable

Conditions System (NOCS) which then automatically searches for the rotavirus

vaccination details for the person at the time of notification from the Vaccination

Information and Vaccination Administration System (VIVAS). Generally there is no

public health follow up undertaken for sporadic cases. Outbreaks of rotavirus in a child

care facility or institution are investigated and managed in the same way as other

institutional outbreaks of gastroenteritis.

Data were extracted from NOCS on 11 July 2017 for all confirmed and probable cases

of rotavirus with onset of disease between 1 January 2006 and 30 June 2017. Cases

were assigned to a geographic Hospital and Health Service (HHS) area based on their

residential address at the time of notification.

Descriptive analyses were performed using Microsoft Excel™ and Stata 14. All rates

were calculated using the Queensland Estimated Resident Population (ERP) 2006 -

2015 published by the Australian Bureau of Statistics.(7) The 2015 ERP was used to

calculate 2016 and 2017 rates as the ERP for these years were not available at the

time of this report. Rates for 2017 quarter 1 and quarter 2 combined were calculated by

dividing 2015 ERP by two to produce an annualised rate.

The proportion of positive rotavirus laboratory results for public hospitals in Queensland

was calculated using AUSLAB data. The number of positive results was divided by total

number of tests ordered by test type. The proportion positive result was then compared

by age group.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 7 -

Results

Rotavirus notifications in Queensland 2006-2017

A total of 14186 notifications have been received in Queensland from 1 Jan 2006 to 30

June 2017 (Quarter 2, 2017). Since surveillance became established in 2006 and the

vaccination program began in mid-2007, there has been a rapid decline in notifications

(Figure 1). Peaks are seen during quarters 3 and 4 and specifically during August

through to October, with 30-40% of annual notifications seen during this time. A peak

can be observed in the third quarter, 2011, and was predominately seen in 4 and 5

year olds with the highest number of notifications in August of that year. These children

were too old to be vaccinated as part of the immunisation program that started in July

2007.

In late 2015 two Queensland laboratories introduced PCR testing for rotavirus infection

as part of viral enteric pathogen panels. The current assays used in these panels do

not discriminate between wild type rotavirus and the vaccine strains. (D Whiley

Pathology Queensland, personal communication, 18 July 2017) As a result, many of

the notified cases in children aged younger than one year, since these assays were

introduced, may not be wild type infections.

Figure 1 Number of notifications of rotavirus in Queensland by year and quarter of onset, 2006- Q2 2017.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 8 -

The highest number and rate of notification is seen in children aged younger than one

year (Figure 2). The average rate of notification is 408 (range 240-628) notifications per

100,000 population per year for this age group during the period 2008-2017. This

compares to the pre-vaccination year of 2006 when rates were 2.5 times greater than

the rates for 2008-2016 for children younger than one year.

The lowest age-specific notification rate is seen in those aged 10-59 years with an

average of 8.1 notifications per 100,000 population per year during 2008-2017.

Over time, the largest decrease in notification rate is seen in children younger than one

year followed by children aged 1-4 years (Figure 2). There is a peak in the notification

rate in children younger than one year in late 2015, coinciding with the introduction of

PCR testing (Figure 2).

*Annualised rate for 1 Jan-30 June 2017

Figure 2 Rates of rotavirus notifications in Queensland by age group per 100,000 population per year, 2006-30 June 2017

Indigenous status of persons notified with rotavirus is limited because this information

is not routinely recorded on pathology requests. Of the total notifications during the

period 2006-2016, 21% of notifications have no status recorded. Of those with

Indigenous status recorded, an average of 12% of notifications per year were from

Aboriginal and/or Torres Strait Islander people (range 8-16%). More recently,

information on Indigenous status has been complete for ≥98% of notifications due to

better electronic linkage with vaccination records in Queensland.

Rates of rotavirus notification by Hospital and Health Service show higher rates for

some regional and remote areas in some years. The rates for these areas can be

influenced by relatively small changes in the number of notifications.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 9 -

Table 1 Number of notifications for Queensland Hospital and Health Services, 2006-30 June 2017.

Hospital and Health Service 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017* Total

Cairns and Hinterland 174 103 69 90 41 55 33 51 32 34 88 60 830

Central Queensland 332 104 68 65 108 145 52 51 44 45 62 24 1100

Central West 6 5 2 0 4 4 2 2 2 2 2 2 33

Darling Downs 123 70 50 40 61 90 43 72 28 68 60 49 754

Gold Coast 112 100 104 73 64 74 73 119 85 118 97 61 1080

Mackay 37 25 7 12 14 40 18 44 16 22 13 17 265

Metro North 573 256 303 213 182 366 225 275 236 231 278 171 3309

Metro South 289 229 168 138 138 233 210 247 238 295 346 256 2787

North West 32 2 11 9 15 14 46 25 11 12 5 9 191

South West 12 12 23 12 6 13 3 2 2 4 6 10 105

Sunshine Coast 203 78 98 64 43 87 72 72 91 123 113 68 1112

Torres and Cape 79 16 8 28 4 41 2 30 1 9 41 7 266

Townsville 268 77 99 59 74 118 83 55 40 46 25 15 959

West Moreton 149 85 45 43 32 63 47 79 60 54 80 92 829

Wide Bay 106 24 29 50 26 43 36 47 28 42 55 37 523

Total 2495 1186 1084 896 812 1386 945 1171 914 1105 1271 878 14143

*1 Jan-30 June 2017

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 10 -

Table 2 Rates of rotavirus notifications for Queensland Hospital and Health Services per 100,000 population per year, 2006-30 June 2017.

Hospital and Health Service 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017*

Cairns and Hinterland 81.2 46.8 30.5 38.8 17.4 23.1 13.7 20.8 12.9 13.6 35.3 48.1

Central Queensland 171.8 52.8 33.8 31.6 52.0 68.7 24.0 22.9 19.4 19.6 27.0 20.9

Central West 49.6 41.4 16.5 0.0 32.6 32.3 16.1 16.1 16.1 16.4 16.4 32.9

Darling Downs 49.4 27.7 19.5 15.3 23.1 33.7 15.9 26.2 10.1 24.5 21.6 35.2

Gold Coast 24.2 20.8 21.0 14.3 12.3 14.0 13.5 21.6 15.2 20.7 17.0 21.4

Mackay 24.0 15.8 4.3 7.2 8.3 23.3 10.2 24.4 8.8 12.1 7.1 18.7

Metro North 72.8 31.6 36.4 24.9 20.8 41.1 24.8 29.7 25.1 24.1 29.1 35.7

Metro South 31.0 24.0 17.2 13.8 13.6 22.6 19.9 23.0 21.9 26.8 31.4 46.5

North West 108.8 6.7 35.7 28.9 47.7 43.9 142.5 76.6 33.7 37.0 15.4 55.6

South West 47.2 47.1 89.5 46.3 22.9 49.3 11.3 7.5 7.5 15.1 22.6 75.5

Sunshine Coast 62.0 23.3 28.4 18.1 11.9 23.8 19.4 19.0 23.7 31.6 29.0 34.9

Torres and Cape 357.3 70.2 34.3 117.7 16.5 166.2 8.0 118.6 3.9 34.7 158.0 53.9

Townsville 129.3 36.4 45.6 26.6 32.8 51.4 35.5 23.1 16.6 18.9 10.3 12.3

West Moreton 72.5 39.9 20.4 18.7 13.5 25.9 18.8 30.7 22.7 20.0 29.7 68.3

Wide Bay 56.8 12.5 14.8 24.9 12.7 20.9 17.3 22.3 13.2 19.7 25.8 34.8

Total 62.3 28.8 25.7 20.7 18.4 31.0 20.7 25.2 19.4 23.1 26.6 36.7

*Annualised rate for 1 Jan-30 June 2017

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 11 -

Vaccination information for children younger than one year notified with rotavirus in Queensland 2008-2015

Table 3 Vaccine doses recorded for children younger than one year notified with rotavirus, Queensland, 2008-2015.

Number of doses recorded

0* 1 2 3

Age in months n

% of age group with no doses n

% of age group with

1 dose n

% of age group with

2 doses n

% of age group with

3 doses

Total number of

notifications

0 144 100 144

1 177 75 60 25 237

2 49 21 179 79 228

3 17 12 125 85 5 3 147

4 11 7 51 34 88 59 150

5 17 13 18 14 91 72 1 1 127

6 16 12 10 8 46 36 57 44 129

7 17 14 14 11 14 11 78 63 123

8 24 15 8 5 14 9 110 71 156

9 17 11 8 5 14 9 112 74 151

10 25 17 5 3 18 12 102 68 150

11 11 18 2 3 9 15 40 65 62

Total 525 29 480 27 299 17 500 28 1804

*no recorded dose in Vivas at the time of notification

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 12 -

The rotavirus vaccination program began in Queensland in mid-2007 using a 3 dose

schedule at 2, 4, and 6 months of age. For children being notified with rotavirus since

2008, the number of documented doses of rotavirus vaccine was compared by month

of age (Table 3). The time period was restricted to exclude cases in 2016 and 2017

that could potentially include vaccine and wild-type rotavirus due to use of PCR for

routine diagnosis in some laboratories.

More children (79-85%) notified at younger ages (2 or 3 months) have received the

recommended doses for their age than those children notified at an age when the 3-

dose schedule should be completed (63-74% at 7 months or older).

Rotavirus Vaccination coverage

Rotavirus vaccines are one of only a small number of vaccines that are not included in

the Australian Immunisation Register calculation of ‘fully immunised’ children at one

year of age, and therefore do not appear in regular coverage reports of the National

Immunisation Program. The most recent information on rotavirus vaccine coverage

was assessed in 2015 for children born during 2014. This report shows that vaccination

coverage for rotavirus has increased since its introduction in 2007, although it remains

lower than other vaccines given at a similar age (2, 4, and 6 months). Coverage is also

lower in jurisdictions who administer the 3 dose schedule compared to the 2 dose

schedule. In 2015, the percentage of 12 month old children immunised against

rotavirus was assessed as 83.2% in Queensland compared with 85.4% across

Australia. (8) In jurisdictions where a three dose schedule is given (as used in

Queensland), this appears to result in lower coverage in Aboriginal and/or Torres Strait

Islander children than non-indigenous children. (8)

Rotavirus testing in Queensland public laboratories 2006-2017

From public laboratory data, the proportion of positive antigen tests for rotavirus

declines sharply as notifications also declined in 2007 (Figure 3). Antigen testing was

the predominant test used until late 2015 when PCR testing numbers began to

increase. During 2007-2014, the proportion of specimens tested that were positive for

rotavirus antigen testing in public laboratories ranged between 10-15%. This compares

with the earlier time period 2000-2006 where the range has been documented as 41-

58%. (4, 6)

Across all years and test types, the proportion testing positive is higher for children

younger than one year compared to other age groups.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 13 -

Figure 3 Proportion of public laboratory tests positive for rotavirus in Queensland by test type and age group, 2006-Q1 2017

Other surveillance systems

The Australian Rotavirus Surveillance Program, together with collaborating laboratories

Australia-wide, conducts a laboratory-based rotavirus surveillance program. The

program began in 1999 and publishes annual reports describing the genotypes of

detected rotaviruses. The Queensland collaborating laboratories in 2015 were Forensic

and Scientific Services, Queensland Paediatric Infectious Diseases Laboratory (Royal

Children’s Hospital), and Pathology Queensland (Central Laboratory plus Townsville).

Genotype analysis in 2015, which included over a thousand samples (80 samples from

Queensland), showed G12P[8] remained the dominant genotype for Queensland and

nationally. (9)

The published annual reports are available at:

http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-pubs-annlrpt-

rotavar.htm

Conclusion

The trend in rotavirus notification data in Queensland during 2006-30 June 2017 shows

a substantial decline since the introduction of the immunisation program. The rates of

notification remain high in children aged younger than one year. Introduction of a new

case definition in 2017 will assist in separating those notifications that are potentially

false positive notifications of disease, due to inadequate discrimination in rotavirus

PCR testing.

Rotavirus in Queensland, 2006-2017 – Communicable Diseases Branch - 14 -

References

1. Ye S, Roczo-Farkas S, Whiley D, Lambert S, Robson J, Heney C, et al. Evidence of false-positive results in a commercially available rotavirus assay in the vaccine era, Australia, 2011 to 2012. Euro Surveillance: Bulletin Europeen Sur Les Maladies Transmissibles = European Communicable Disease Bulletin. 2013;18(21).

2. Ye S, Lambert SB, Grimwood K, Roczo-Farkas S, Nimmo GR, Sloots TP, et al. Comparison of test specificities of commercial antigen-based assays and in-house PCR methods for detection of rotavirus in stool specimens. J Clin Microbiol. 2015;53(1):295-7.

3. Newall AT, MacIntyre R, Wang H, Hull B, Macartney K. Burden of severe rotavirus disease in Australia. J Paediatr Child Health. 2006;42(9):521-7.

4. Buttery JP, Lambert SB, Grimwood K, Nissen MD, Field EJ, Macartney KK, et al. Reduction in rotavirus-associated acute gastroenteritis following introduction of rotavirus vaccine into Australia's National Childhood vaccine schedule. Pediatr Infect Dis J. 2011;30(1 Suppl):S25-S9.

5. Field EJ, Vally H, Grimwood K, Lambert SB. Pentavalent rotavirus vaccine and prevention of gastroenteritis hospitalizations in Australia. Pediatrics. 2010;126(3):e506-e12.

6. Lambert SB, Faux CE, Hall L, Birrell FA, Peterson KV, Selvey CE, et al. Early evidence for direct and indirect effects of the infant rotavirus vaccine program in Queensland. Med J Aust. 2009;191(3):157-60.

7. Australian Bureau of Statistics Catalogue No. 3235.0 - Population by Age and Sex, Regions of Australia, 2015

8. Hull B, Hendry A, Dey A, Beard F, Brotherton J, McIntyre P. Annual Immunisation Coverage Report 2015. National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, The Children's Hospital at Westmead and University of Sydney, 2015.

9. Roczo-Farkas S, Kirkwood CD, Bines JE. Australian Rotavirus Surveillance Program annual report, 2015. Commun Dis Intell. 2016;40(4):E527-E38.

Department of Health

www.health.qld.gov.au