Caroline van GemertField Epidemiology Training Program, Australia

The Masters of Applied Epidemiology is funded by the Australian Department of Health and Ageing

Social contacts of student cases of Pandemic Influenza A (H1N1) 2009 during implementation of social distancing measures in May-June 2009 Victoria, Australia

Background

Pandemic Influenza in Australia

• One of the first regions in southern hemisphere with cases

• First evidence of local transmission of pandemic influenza in Melbourne, Victoria

Melbourne, Australia

• Capital of Victoria• Second-most southern

capital in Australia• Winter months June -

August• Approximately 4 million

people• Highly culturally and

linguistically diverse

Role of schools in transmission of pandemic influenza

School settings are important because of:

• High rates of contact between students

• Prolonged exposure in classes

• Contact with students in range of age groups

Objectives of study

• To describe the regular social contacts of confirmed student cases of pandemic influenza; and

• To describe students social contacts during the period before and after symptom onset

Methodology

Methodology

• Study design: Cross sectional study

• Case definition: Laboratory-confirmed cases who attended a Victorian primary or secondary school that had a high case-load (over 10 cases) of confirmed cases

• Notification period: Before 3 June 2010

• Data collection: Interviewer administered interview

• Incentive: $30 (Australian) voucher

• Ethical considerations: Written consent

Information collected

•Gender

•Age

•Year level

Demographics

•Symptom details

•Date of symptom onset

Case details

•Regular school and non-school activities

•Group size for each group

•Number of primary links in each group

•Attendance/participation in each group in potential exposure and infectious period

Social contact information

Analysis

Preliminary analysis (presented here):• Average number of groups, group size and number of

primary links• Participation in each activity type during potential

exposure and infectious period

Long-term analysis (not presented here):• Modelling of social networks using social network

analysis

Results

Response rates

857 confirmed cases notified to VDOH during

Contain Phase

434 (50.7%) of cases excluded as they did not

attend school

423 (49.3%) of cases attending one of 152 schools in Victoria

162 (38.5%) cases from seven schools had >10

confirmed cases attending the school

35 (23.4%) of eligible cases not contactable

25 (15.4%) of eligible cases refused participation

/ not available

99 (61.1%) of eligible cases interviewed

Participant description

n %

Schools

Number of schools that students attended 6 100%

Number of primary (junior) schools 1 14.3%

Number of secondary (middle and high) schools 6 85.7%

Gender

Male 43 43.4%

Female 56 56.6%

Age Group

6-7 years 4 4.0%

10-11 years 5 5.1%

12-13 years 9 9.1%

14-15 years 48 48.5%

16-17 years 33 33.3%

Regular activities reported by students

Regular activitiesAverage

number of groups per participant

Median size of group

Average number of

primary links per groupn %

School 99 100.0 4 20 3

University class 9 9.1 1 12 2

Part-time work 18 18.2 1 20 10

Sports 44 44.4 1 16 6

Religious group/service 20 20.2 1 175 5

Other activities 81 81.8 2 30 20

Regular activitiesAverage

number of groups per participant

Median size of group

Average number of

primary links per groupn %

School 99 100.0 4 20 3

University class 9 9.1 1 12 2

Part-time work 18 18.2 1 20 10

Sports 44 44.4 1 16 6

Religious group/service 20 20.2 1 175 5

Other activities 81 81.8 2 30 20

What types of activities did students report?

Sports

Team

Outdoor

Individual

Indoor

Other activities

Sports match

Cinema

Party

Friends houseGirl guides

Youth Group

Private tuition

Part-time employment

Supermarket

Shop/

Department Store

Fast food restaurant

Cafe

School-based non-classroom

activities

Camp

Social (prom/formal)

Carnival

Excursion (field trip)

Religious Group / Service

Church

MosqueTemple

Participation in potential exposure and infectious period

School0

102030405060708090

100

Num

ber o

f stu

ents

University class

Part-time employment

Sport Religious ac-tivity/service

Other activi-ties

0102030405060708090

100

Participated in potential exposure periodParticipated in potential infectious period

Num

ber o

f eve

nts

Figure 1: Number of students that reported attending school

Figure 2: Number of events reported by students

Part-time workReligious groups/activities

Discussion

Implications and recommendations from major findings

1. High level of school attendance when

potentially infectious

Improve communication of

individual-level strategies

Lower threshold for school closure?

2. Potential evidence for the role of non-classroom school-organised activities

in transmission

Consider cancellation of non-classroom school-organised

activities

3. Potential evidence for the role of non-

school based activities in

transmission

Students potential “bridge” of transmission

Improve communication of individual-level

strategies

Acknowledgements• Participating students• Victorian Department of Health• Victorian Department of Education and Early Childhood Development• Catholic Education Office, Melbourne• Research Assistants at the Burnet Institute • Margaret Hellard receives funding from the NHMRC for a Senior Research Fellowship.• This work was funded by an Australian Government National Health and Medical Research Council grant

(application ID 603753) for research on H1N1 Pandemic Influenza 09 to inform public policy.

Authors • Caroline van Gemert, Centre for Population Health, Burnet Institute, Australia and National Centre for Epidemiology

and Population Health, Australian National University, Australia• Isabel Bergeri, Centre for Population Health, Burnet Institute, Australia • James Fielding, Victorian Department of Health, Australia and National Centre for Epidemiology and Population

Health, Australian National University, Australia• Nasra Higgins, Victorian Department of Health, Australia • Rosemary Lester, Victorian Department of Health, Australia• Hassan Vally, National Centre for Epidemiology and Population Health, Australian National University, Australia• Emma McBryde, Victorian Infectious Diseases Reference Laboratory, Australia and Royal Melbourne Hospital,

Australia and Department of Medicine, University of Melbourne• Pip Pattison, School of Psychology, University of Melbourne• Margaret Hellard, Centre for Population Health, Burnet Institute, Australia