[ELI5]:Why does the flu suddenly disappear when summer arrives?Does the heat kill the flu?


[ELI5]:Why does the flu suddenly disappear when summer arrives?Does the heat kill the flu?

In: Biology

It still exists, in fact the two times I’ve personally had the flu it was in the middle of the summer.

However, winter helps the flu out in spreading, generally we’re closer together in winter and don’t go out as much, perfect conditions for the flu to spread itself.


> “The virus survives better in cool, dry temperatures,” Simanek said. And that’s thanks to a protective gel-like coating that surrounds the flu virus while it’s in the air.

> The flu is an airborne infectious disease. So in order to spread, the virus needs to survive long enough in the air to travel from one person to the next. And that’s where the virus’s gel-like coating helps when it’s cold outside.

> In colder temperatures, that capsule, which is made of fats and oils called lipids, hardens into a shell around the virus. This protects the virus and keeps it alive long enough to spread between victims.


Ultraviolet light in sunshine kills bacteria and viruses on surfaces more in the summer so it’s harder to catch something from door handles etc.

Dr. Peter Palese a microbiologist was interested in a 1918 article about flu pandemic, the author stated that the labs guinea pigs were infected and died. So Dr. Palese infected guinea pigs and kept them in varying temperatures (41 F, 68 F, and 86 F) and humidity (20%-80%). He found out that the virus survived and transmitted better in low humidity and temperature. A 1960s paper further mentioned that virus was able to service 23 hours at a temp of 43 F with very low humidity. At a temperature of 90 F and high humidity survival rate was diminished at even one hour into incubation.
There are also other theories about the flu being present only in winter such as the lack of activity and isolation in cold weather, and shorter days and less sunlight aka decrease in Vit-D and melatonin which the then leads to weakening of your immune system.

There is much more to it I’m sure but it’s certainly one of the major factors, uv light killing bacteria and virus on exposed surfaces.