Why are viruses more active in winter?

Why are viruses more active in winter?

Specialists are concerned about a potential spike in influenza and coronavirus cases next winter, and their concerns are hardly surprising. While viruses can certainly circulate at any time of the year, a variety of respiratory infections — including influenzas, coronaviruses, and common colds — are always more active during the winter.

While the seasonal increase in these viruses is widely accepted and recognizedScientists are still struggling to understand why the winter season stimulates its spread. Although there are various theoriesthey are still not sure which explanation, or combination of explanations, is closest to the truth.

Some of their theories emphasize that winter conditions can cause people to behave in ways that increase infections, while others claim that winter weather weakens people’s natural protections or creates the ideal conditions for viruses to circulate and spread. spread. Here’s what you need to know about some of the leading theories.


More about the flu and COVID-19:

  • Scientists say the simultaneous rise in seasonal influenza and coronavirus could cause a “twin” this year, adding additional strain to the medical system.

  • This season could see an increase in combined flu and COVID coinfections, also called “flurone.”


Theory 1: Winter conditions keep people indoors, increasing the spread of infection.

A common explanation for an increase in viruses concerns the behavior of people. According to this theory, winter conditions may cause people to stay indoors and spend more time in close contact with others. East, scientists sayit increases the probability that infected droplets will pass from person to person through the processes of breathing, speaking, sneezing or coughing.

In fact, studies confirm there is a connection between the seasonality of diseases and people congregating indoors, which can increase survival and transmission of the virus.

Theory 2: Winter conditions weaken people’s lives internal protections, increasing the risk of infection.

Other explanations focus on our own physiology. According to these theories, winter weather may weaken the physiological protections within our own immune systems that normally prevent invasion and infection by respiratory viruses. For example, some specialists suspect that the short, gloomy days of winter can reduce our intake of vitamin Dundermining our immune system and making us more susceptible to infections.

Several similar studies suggest that dry winter air dries out the protective mucus that lines the inside of our nasal passages, preventing the sticky substance from trapping and neutralizing invading viruses. Additional investigation it also reveals that the coolness of the air could constrict the blood vessels along our throat and nose, preventing the vessels in those areas from mustering an adequate number of white blood cells to fight off viral intruders.

Theory 3: Winter conditions create ideal conditions for viruses, increasing the risk of infection.

A final collection of theories connects to the viruses themselves, claiming that winter weather increases their longevity and improves their ability to circulate. In fact, some scientists think that the dry and cold conditions of the season allow the viruses to remain in the air for longer periods of time. This can cause them to break up into such small fragments that they can remain active and float until they are inevitably inhaled.


Read more: The possibility of “Flurona” and what two viruses can do at once


Related studies are also advancing that arid winter air may favor viral spread because it is interspersed with fewer interfering moisture molecules. According to these studies, the absence of moisture molecules means there is nothing to clog viruses or distort their surfaces, processes that normally inhibit a virus’s ability to invade the body.

Nor does a virus’ preference for winter weather simply go away once they’ve successfully infected someone. According to A study, respiratory viruses tend to thrive and replicate in cooler internal conditions and are also less likely to commit a form of cell suicide called “apoptosis” in cooler areas within the body. This, the study authors state, means that “temperature has profound effects” on “the outcome of common cold infections.”

Ultimately, while it is clear that something about the winter season inspires an increase in viral activity, the ability of any of these theories to sufficiently explain respiratory infection patterns remains ambiguous. While they may all play a part in the seasonal disease story, only future research will reveal the full story.

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