The flu vaccine provides annual protection against influenza viruses that mutate each season. WHO recommends vaccination for everyone ≥6 months, with priority for:
- Seniors ≥65
- Children 6 months – 5 years
- Pregnant women in 2nd or 3rd trimester
- Patients with chronic illness (asthma, diabetes, cardiac, renal, immunocompromised)
- Healthcare workers and public-facing staff
Effectiveness: reduces flu risk by 40–60%, and if you still catch it, symptoms are usually milder.
Best timing: 2–4 weeks before flu season (Indonesia: April–May ahead of the transitional rainy season). Antibodies form in ~2 weeks and last ~6 months.