Annual Influenza Vaccine:
Why Flu Is More Serious Than People Think

Influenza is routinely dismissed as "just a bad cold" — but the two are caused by completely different viruses with very different consequences, particularly in young children. Influenza virus causes abrupt-onset high fever, profound myalgia (body aches), and exhaustion that common cold viruses simply do not produce.

What Influenza Can Do to Children

In young children, influenza is not simply a miserable week at home. It can cause:

• Febrile seizures — high fever in toddlers can trigger fits
• Croup — laryngotracheitis causing stridor and breathing difficulty
• Viral encephalitis — brain inflammation, rarely but devastatingly
• Myocarditis — heart muscle inflammation
• Secondary bacterial pneumonia — influenza damages the airway lining, allowing bacterial superinfection
• Death — children under 5 without underlying conditions die from influenza each year

Singapore's Influenza Year

Unlike temperate countries where influenza is seasonal (winter peak), Singapore experiences year-round influenza circulation with two broad activity peaks: typically April–May and October–November. This means there is no truly "safe" season — children in childcare and school are exposed throughout the year.

Why Annual Vaccination?

The influenza virus undergoes rapid antigenic drift — small mutations in its surface proteins that allow it to partially evade prior immunity. The WHO coordinates global surveillance and reformulates the vaccine annually to match the predicted dominant circulating strains for that season. Last year's vaccine may provide partial but not full protection against this year's strains. Annual vaccination is therefore not optional for ongoing protection — it is the mechanism by which protection is maintained.

First Time Vaccinating Under 9 Years

Children under 9 years receiving the flu vaccine for the very first time require 2 doses, given 4 weeks apart. Their immune system has never encountered influenza before, and a single dose does not generate sufficient protection. From the second year onward: 1 dose annually.

Brands Available in Singapore

• Fluarix Tetra (GSK): Quadrivalent inactivated — 4 influenza strains (2A + 2B). Widely used in Singapore.
• Vaxigrip Tetra (Sanofi): Alternative quadrivalent. Available at polyclinics and CHAS GP clinics.
• Afluria Quadrivalent (Seqirus): Available at some private GP clinics.