Why Is There A Winter Flu Season?

Popular Science ^ | January 17, 2013 | Emily Elert

[ProtectOurFreedom]

Flu season is in full swing across the U.S... it always happens in winter. ...everywhere on Earth where people have a winter season, they also have a flu season. Part of what makes the timing of each flu season unpredictable is that scientists still don't understand exactly why we have one at all. There have, of course, been lots of theories why flu peaks in winter:

1. people spend more time indoors, with the windows closed, breathing each other's air.
2. darkness (i.e. lack of Vitamin D and melatonin) and cold of winter weaken our immune systems, making us more susceptible to the virus
3. regardless of how we deal with the cold--the flu virus thrives in the cold, dry air of winter, but suffers in the warm, humid air of summer
4. winter flu is ushered in by changes in air circulation in the upper atmosphere.

...scientists had a hard time thinking up ways to test these theories: they needed to be able to run experiments, but researchers aren't allowed to infect humans with nasty illnesses, and most lab animals aren't affected by the flu the same way people are. But then, in 2007, a medical researcher named Peter Palese stumbled across an 80-year-old journal article that reported that guinea pigs get infected and pass on the flu just like humans.

Palese decided to test theory #3--the idea that the flu virus does better in cold, dry air than warm, humid air. He acquired some guinea pigs and ran several experiments to see how temperature and humidity affect the way the flu spreads. In each experiment, he injected half the guinea pigs with influenza A (the common flu), and put them in a crate next to a crate of uninfected animals.

[Red Badger]

I’ve never had the flu and I’m 65.

But I live in Florida!...................

[arthurus]

As do I. South Florida has a climate that should preclude colds and flu for those who are outside in short sleeves every day.

[Red Badger]

I live in the Panhandle, used to live in Margate................

[arthurus]

It gets chilly and often overcast all day here in northwest FL.

[Red Badger]

Like right now, but this weekend will be sunny and cool...............

[goodnesswins]

And vitamin K too, right?