# Why Colds and Flu during the colder months of the year? **URL:** \ **Category:** Factual Questions\ **Created:** [October 30, 2005, 2:12am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540 "2005-10-30T02:12:27Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![phi\_a\_low\_gen](https://avatars.discourse-cdn.com/v4/letter/p/5f8ce5/32.png) [@phi\_a\_low\_gen](https://boards.straightdope.com/u/phi_a_low_gen)\ **Post date:** [October 30, 2005, 2:12am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/1 "2005-10-30T02:12:27Z")
Why are there or is there more of a prevalence of colds and flu during the fall/winter months than the spring/summer months? In locations where the weather is hot all the time i.e. a place like Aruba, how does the prevalence of colds and flu differ than say the north east of the US? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [October 30, 2005, 2:24am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/2 "2005-10-30T02:24:23Z")
Colder weather means more time spent inside. More time spent inside means more face-to-face contact, more hands on door knobs, more sharing of air space in general. This is the sole reason for more shared viruses. Wash your hands! ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [October 30, 2005, 2:32am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/3 "2005-10-30T02:32:32Z")
Also it’s the season when the little disease vectors return to school. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [October 30, 2005, 2:35am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/4 "2005-10-30T02:35:48Z")
[The Master speaks.](http://www.straightdope.com/classics/a4_104.html). Don’t get to cocky with the answers. Nobody really knows for sure and every theory has a strong counterargument. The person that figures this out will win a Nobel Prize. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 30, 2005, 4:07am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/5 "2005-10-30T04:07:39Z")
> [@Leaffan](#): > > Colder weather means more time spent inside. More time spent inside means more face-to-face contact, more hands on door knobs, more sharing of air space in general. This is the sole reason for more shared viruses. I don’t buy this. In someplace like my office, we spend the exact same amount of time indoors with the exact same people, and colds are definitely more prevalent in the winter. What’s the traditional cold season in the southern hemisphere? ---
**Author:** ![rfgdxm](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@rfgdxm](https://boards.straightdope.com/u/rfgdxm)\ **Post date:** [October 30, 2005, 4:28am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/6 "2005-10-30T04:28:51Z")
> [@Little Nemo](#): > > Also it’s the season when the little disease vectors return to school. THIS likely is a significant factor. To ultrafactor: while you and your co-workers may be cooped up at work the same time year round, this isn’t the case for kids. Kids are cooped up more when school is in session, which is the colder months. The kids then share their viruses with their parents that do work. ---
**Author:** ![rfgdxm](https://avatars.discourse-cdn.com/v4/letter/r/c0e974/32.png) [@rfgdxm](https://boards.straightdope.com/u/rfgdxm)\ **Post date:** [October 30, 2005, 4:32am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/7 "2005-10-30T04:32:45Z")
> [@ultrafilter](#): > > What’s the traditional cold season in the southern hemisphere? Note: in the Southern Hemisphere there aren’t many places where people actually live it gets so cold folks avoid going outside. Not many blizzards in South America, Africa, and Australia. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [October 30, 2005, 9:42pm UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/8 "2005-10-30T21:42:11Z")
> [@rfgdxm](#): > > > [@ultrafilter](#): > > > > What’s the traditional cold season in the southern hemisphere? > > Note: in the Southern Hemisphere there aren’t many places where people actually live it gets so cold folks avoid going outside. Not many blizzards in South America, Africa, and Australia. In my experience the traditional cold and flu season is during winter and early spring i.e. June, July, August, September ---
**Author:** ![Guinastasia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guinastasia/32/5751_2.png) [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)\ **Post date:** [October 31, 2005, 12:29am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/9 "2005-10-31T00:29:51Z")
I thought maybe it was because we keep our homes and buildings warmer, and germs breed better? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [October 31, 2005, 1:13am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/10 "2005-10-31T01:13:51Z")
> [@rfgdxm](#): > > THIS likely is a significant factor. To ultrafactor: while you and your co-workers may be cooped up at work the same time year round, this isn’t the case for kids. Kids are cooped up more when school is in session, which is the colder months. The kids then share their viruses with their parents that do work. Yeah, but they’re cooped up nine months out of the year, and at least where I am, colds and other diseases are only really prevalent when it’s actually cold out–not just cool, like most of the school year, but actually cold. ---
**Author:** ![Fridgemagnet](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@Fridgemagnet](https://boards.straightdope.com/u/Fridgemagnet)\ **Post date:** [October 31, 2005, 1:38am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/11 "2005-10-31T01:38:39Z")
What **Little Nemo** said, I reckon. Kids return from their summer holidays with exotic new diseases, and trade them all at school or college to form some sort of student hypercold arrangment. It’s quite an assault on anyone’s immune system. ---
**Author:** ![antechinus](https://avatars.discourse-cdn.com/v4/letter/a/fbc32d/32.png) [@antechinus](https://boards.straightdope.com/u/antechinus)\ **Post date:** [October 31, 2005, 10:29am UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/12 "2005-10-31T10:29:03Z")
In the book Bad Medicine, the author Christopher Wanjek, says that in addition to people being cooped up and in closer contact with each other, the cold virus life cycle is most active in the wintertime. If the virus was more prevalent in the summer, it wouldnt be called a cold. ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [October 31, 2005, 2:24pm UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/13 "2005-10-31T14:24:17Z")
I haven’t seen anyone yet mention what I think is likely - when I get cold, I sneeze a lot more. Therefore I sneeze a lot more in winter than summer, and sneezes are great vehicles for viruses to propagate. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [October 31, 2005, 2:52pm UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/14 "2005-10-31T14:52:41Z")
> [@CurtC](#): > > I haven’t seen anyone yet mention what I think is likely - when I get cold, I sneeze a lot more. Therefore I sneeze a lot more in winter than summer, and sneezes are great vehicles for viruses to propagate. Counterpoint: Summer is prime time allergy season with even more people sneezing. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [October 31, 2005, 3:13pm UTC](https://boards.straightdope.com/t/why-colds-and-flu-during-the-colder-months-of-the-year/328540/15 "2005-10-31T15:13:59Z")
It’s likely a number of contributing reasons. -Virus mutation cycles -Less sunlight in winter = inreased vitamin D deficiency. -Warm heating ducts are more germ friendly than cold ones. -Children return to school: germs are given transport to new locations -People are less active, less healthy during colder months = reduced immune system -Human stress levels (and this might be the most under rated factor) really get worse when kids return to school, vacations end and holidays and bill bear down on everyone. Stress = vulnerable immune system -Interpretation/diagnosis bias: Sneeze in May and you (and docs) call it allergies. Sneeze in November and it is a “cold”.