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.

[ProtectOurFreedom]

Reading all the articles about 2019-nCoV and the other three animal viruses spreading in China got me wondering why influenza occurs mainly in the winter. I found this interesting layman's paper from seven years ago on this topic. Continues...

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At a temperature of 41 degrees, all four of the exposed guinea pigs caught the flu, but when Palese repeated the experiment at 68 degrees, only one of the exposed animals was infected. And when he and his colleagues ran the test at a temperature of 86 degrees, none of the exposed animals got sick.

Since winter air is also much drier than summer air--cold air can't hold as much water vapor--the researchers also ran experiments where they varied the humidity in the room but kept the temperature constant: the drier the air, they found, the more animals got sick.

Palese's guinea pig study showed that the influenza virus really does spread more effectively in cold, dry air--but it left one important question unanswered: why?

One possibility has to do with the way the flu spreads through air. When an infected person breathes in and all the tiny airways in their lungs open, a thin film of fluid stretches across the opening airways and then breaks, releasing little virus-containing droplets into the air in the lungs. When the person breathes out, those droplets are expelled into the air, where they begin to fall toward the ground.

...the flu droplet's earthward fall is where humidity comes in. As this droplet falls, it also begins to evaporate. The drier the air is, the more moisture evaporates from the droplet, and the smaller the droplet gets. AND if it gets smaller, the effect of air resistance gets bigger. Eventually, if enough of the droplet evaporates, the flu virus is whisked away on air currents and can float around for days, until someone else breathes it in.

One study found that the flu virus survives for much longer in low humidity than high humidity.

Quite possibly, the flu's annual winter-time parade through our immune systems has to do with both factors: the virus survives better and transmits more easily in cooler, drier air. The case isn't closed yet--and researchers are still looking into some of those other theories, like the idea that our immune systems are weaker in winter--but, for anyone looking for ways to avoid the seasonal flu (in addition to the flu shot, of course), a portable humidifier seems like a good place to start.

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I'm sure there are lots of scholarly papers on this topic. To all of the microbiologists on FR -- are these theories valid? What do you think? Also, does coronavirus follow these same general trends of getting much worse in winter? So far, we haven't seen much of 2019-nCoV in tropical climates or south of the equator where it is summer. The vast majority of the cases are occurring in areas where it is now winter.

[Red Badger]

Excuse me while I go put on a HUGE pot of boiling water................................

[untenured]

I’m no microbiologist, but I was long ago told that the simple fact that our nasal passages are much drier in the winter makes it easier for viruses to get into the body through the nose.

[Graybeard58]

Simple answer? Global warming.

[saintgermaine]

This is a RE-POST as I am wondering if the same would be beneficial against this new virus? Also it worked like a charm against the H-1 N-1 so there may be a good possibility to work against the newer flu-virus as well, it certainly can’t hurt as it also boosts the glutathione level.

From what I recall when the H-1 N-1 virus made its round in 2009 also know as the swine flu virus some one suggested here on FR to use NAC or N-Acetyl Cysteine and to make it work even better along with a healthy dose of buffered C. I have a hunch who ever this person was he may have been associated with the medical profession. I have been taking it ever since with good results as NAC is also a precursor to glutathione one of the most potent anti-oxidants and beneficial for a host conditions. But my main question is will it also be beneficial against this new virus which is circulating? No doubt that there may be a knowledgeable Freeper with a medical background amongst the readers who may possible be able to shed some light on this question. As for myself I do believe that a healthy dose of NAC in combination with buffered ascorbic acid ( C ) certainly can not hurt, along with some sunshine vitamin ( D )

[edwinland]

Good article.

Moral of the story: buy yourself a good humidifier and also send one as a present to your parent or grandparents ... older people are much more at risk during flu season.

[ProtectOurFreedom]

“Global Warming”??

Nah. Trump.

[rxsid]

Yes, good advice. Just remember to clean it periodically.

[KobraKai]

The question is not why do we contract the flu in the winter. The question is why does the flu keep re-occuring every year like clockwork? It’s because China is a cesspit, that’s my contention. They still partake in open air meat markets, they have barbaric standards for public health and the way they keep any livestock. Its nothing more than a breeding ground for viruses to mutate and infect people. All these flu viruses stem from chickens and pigs.

Just because China has sophisticated modern architecture, doesn’t translate to the way their human population lives. They are still centuries behind western civilization.

[agatheringstorm]

There are numerous studies showing that Vitamin D deficiency is a significant factor in the so-called “cold and flu season” of wintertime. On a sunny day, a person who is outside in shirt sleeves and shorts will generate thousands of IU of vitamin D. In the winter, due to far less exposure to the sun, the body’s vitamin D level drops. Vitamin D enhances the immune system, so a drop in vitamin D reduces the immune system’s efficacy. Thus, taking supplemental vitamin D during winter maintains the immune system’s strength, helping to fight off cold and flu viruses.

[Ruy Dias de Bivar]

***influenza virus really does spread more effectively in cold, dry air***

Yet the 1918 flu also hit the Eskimos and the tribes of the hot, humid Amazon basin hard.

[aimhigh]

The author forgot one contributing factor - the Halloween sugar feast.

[mad_as_he$$]

Interesting post...thanks.

[chajin]

Yet the 1918 flu also hit the Eskimos and the tribes of the hot, humid Amazon basin hard.

It would seem to me that if there are enough viri they could overwhelm any deleterious-to-them environment, and that was likely the case with the Spanish flu. Sanitation in the first world, San Francisco notwithstanding, has greatly increased in the last 100 years.

[IamConservative]

https://www.vicks.co.uk/en-gb/shop-products/vicks-cold-prevention-products/vicks-first-defence-nasal-spray

I have found this product to work very well. It is a nasal spray you use at the first sign of cold or flu. Stops it in its tracks for me. YMMV. It is not sold directly in the US, but you can buy on Amazon.

[eastexsteve]

The question is not why do we contract the flu in the winter. The question is why does the flu keep re-occuring every year like clockwork? It’s because China is a cesspit, that’s my contention. They still partake in open air meat markets, they have barbaric standards for public health and the way they keep any livestock. Its nothing more than a breeding ground for viruses to mutate and infect people. All these flu viruses stem from chickens and pigs.

The reason the flu keeps reoccurring is because it keeps mutating. This is the same reason we can't do away with the common cold. Thus, you can't create a vaccination that lasts forever. And, not everyone gets a flu vaccination. So, even in the summer months when flu transmission is low, it still gets passed around somewhere.

[rxsid]

"Just because China has sophisticated modern architecture, doesn’t translate to the way their human population lives. They are still centuries behind western civilization."

Some people are confused by this. They see modern equipment in some Chinese hospital on the news and think their health care system is 1st world like ours. When in reality, it's still a 3rd world health care system in many ways.

Primary care is delivered mainly through village doctors and health workers in rural clinics.

Historically, in rural areas, most healthcare was available in clinics providing rudimentary care, with poorly trained medical personnel and little medical equipment or medications, though certain rural areas had far higher-quality medical care than others...[8][9][10][11][12]
https://en.wikipedia.org/wiki/Healthcare_in_China

It's no wonder at all, that 99.8% of the deaths for this new coronavirus occur in China.

[wastoute]

Some of the earliest research on viruses was done in Norwegian mining communities who were “frozen in” all winter. Their communities never got the flu until the port thawed and ships could come in. In the Spring. They had no flu in the winter.

[ProtectOurFreedom]

I read about Vick's "First Defence" here on FR this past summer. I bought a couple of bottles on Amazon and have been using it in conjunction with AirBorne Original tablets.

I have felt one or two incipient cold or flu episodes coming on this winter and I now believe First Defence actually does either stop the disease in its tracks or greatly ameliorates the symptoms.

People are concerned that the product does not come in safety packaging and my daughter is very leary of the possibility of Chinese counterfeit products being sold on Amazon. The last batch I purchased on Amazon was shipped by some company in the U.K.

[goodnesswins]

And Christmas “sugar feast”