1
Elderly Community Service Centre/ Individual Register
2
Vaccination before winter
Since Sep 2016
Free influenza vaccination for
participants;
free blood test before and
1 month after injection*
Free influenza vaccination for
participants;
free blood test before and
1 month after injection*
3
Each year influenza season
Follow-up call regularly
Arrangement for participant with
flu-like symptoms to collect samples
Arrangement for participant with
flu-like symptoms to collect samples
4
Vaccination before next summer
Since Apr 2017
Free influenza vaccination or
placebo injection for participants;
free blood test before and
1 month after injection*
Free influenza vaccination or
placebo injection for participants;
free blood test before and
1 month after injection*
5
Annual follow-up
Since Sep 2017
Free blood test* and
free influenza vaccination
Free blood test* and
free influenza vaccination
* The blood collected will be stored in the School of Public Health, the University of Hong Kong for antibody levels and assessing immune responses to the seasonal flu shot