system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the flu seasonal? Does it take vacation the rest of the year?
gpt
The flu thrives when there is less ventilation/fresh air circulating. For most folks, this happens when it is colder out & people are more apt to be inside. Flu season is in different months in the southern hemisphere, so it doesn't take a break, just infects during the coldest months.