Like the flu, SARS-Cov 2 becomes seasonal. Despite our efforts to contain the pandemic, our adversary is particularly formidable in winter. Jérome Salomon, the Director General of Health, recalled Monday: “we know that winter is the worst season to face influenza viruses or respiratory viruses in general”. First, because we live more confined inside our homes, virus particles therefore remain suspended in the indoor air. While outside, the wind drives them away and disperses them before they reach our mucous membranes. In fact, in summer or in spring, viruses are still there, but they do less damage because we spend more time outdoors.
We are also less well equipped to face it in winter. Our skin sees less the sun. As a result, we can have vitamin D deficiency, which is necessary for our immune system. In addition, our body needs energy to face winter. When our nose breathes colder air, our nasal mucous membranes bring water to our body temperature before sending this air into our lungs. That’s why we often have a runny nose. But this defense strategy also dries up our mucus, which is a very useful barrier against viruses. This makes it easier for them to enter our body and infect our cells.
The virus is wrapped in a small film of fat that protects it when it rests on particular surfaces. When the weather is nice and hot, UV rays and heat quickly destroy this protective envelope. Without a host to contaminate, the virus also dies. On the other hand, when it is cold and dark, it stays protected longer. It is not for nothing that clusters emerged in slaughterhouses last spring. These are confined, cold places. And loud: in addition, employees must speak loudly.
Moreover, China is still very wary of frozen products. WHO believes there is no evidence of contamination from food packaging. But Beijing last month conducted checks on more than 800,000 frozen products from abroad after finding traces of the virus on packages of frozen beef from Brazil.