I don't see why it should be all year. There isn't much specific to flu that makes it come in seasons that covid doesn't. The more people have been immunised even with a weakened immunity by vaccines or having been sick the more resistance covid will find each time it comes. The trick is to make sure the mutations are kept in check and new vaccines come.
Flu x2 and this time the season is all year
I don't see why it should be all year. There isn't much specific to flu that makes it come in seasons that covid doesn't. The more people have been immunised even with a weakened immunity by vaccines or having been sick the more resistance covid will find each time it comes. The trick is to make sure the mutations are kept in check and new vaccines come.