The flu shot: when in the year, and who needs it every year
Flu in Thailand peaks twice a year, and the vaccine protects for about a year — so the month you have it matters. This sets out the recommended window, the groups who should have it every year without a second thought, and the annual question about strains.
The recommended window
Flu in Thailand is commonest in the rainy season (June–September), with a smaller wave around the turn of the year. The southern-hemisphere formulation used here arrives around April–May, so the best window is May–June — two weeks before the rains for immunity to build. Late is still better than never: a September shot still covers the year-end wave.
Who should have it every year
Everyone 65 and over; anyone pregnant at any stage; anyone with a chronic condition (diabetes, heart, lung or kidney disease, asthma); anyone severely overweight; children from six months to two years; and anyone caring for or working closely with these groups. They qualify for a free dose at state facilities during the campaign. Healthy adults with no risk factor still gain — fewer sick days, less passed on at home.
Strains, and the questions asked every year
The formulation changes every year to the strains the WHO expects, so last year’s shot does not cover this year. It is an inactivated vaccine and cannot give you flu; a sore arm or feeling off-colour for a day or two is the immune response, not an infection. It can be given alongside other vaccines the same day, and most people with egg allergy can have it — only those with a history of severe reaction should have it somewhere equipped to manage one.
