What Causes a ‘Flu Season’ and Why Does It Change Every Year?

The flu is like a party that changes guests each year. Sometimes it brings the loud, energetic kids, other times the quiet, sneaky ones. The reason? The virus likes to switch up its outfit so people can’t always recognize it.

Why It Changes

The flu virus has different costumes (called strains), and sometimes it swaps them out. If you’ve seen one version before, you might not remember the next one, that’s why you get sick again.

Take the quiz →

Examples

A child gets sick with the flu this year, but their brother who had it last year stays healthy.
The same teacher catches the flu twice, once in December and again in February, because they got two different versions of the virus.
Your friend didn’t get sick this winter, but now they’re sneezing all over the place in spring.

Ask a question

Discussion

Recent activity

Categories: Health · flu,influenza,immunity