Meet any of the following criteria are eligible to join the study:
Aged 67–84 years
Have not received 2019/20 seasonal influenza vaccine
Willing to receive seasonal flu shot in coming 2 years
Meet any of the following criteria are not eligible to join the study:
- Signs of dementia or significant cognitive impairment and not competent to give consent.
- Medical conditions not suitable to receive inactivated influenza vaccines such as severe allergic reaction after previous dose of any influenza vaccine; or to a vaccine component, including egg protein; moderate or severe acute illness with or without fever after any previous influenza vaccination; or a history of Guillain-Barré syndrome (GBS) within 6 weeks of previous influenza vaccination.
- Report medical conditions not suitable to receive intramuscular injection including bleeding disorders and habitually taking anticoagulants (with the exception of antiplatelets such as aspirin).
- Medical conditions not suitable to receive inactivated influenza vaccines as determined by a clinician.