At first it was thought that it was just the cold, but there are several studies that indicate that low temperatures by themselves can also make viruses more resistant. The common cold or cold is caused by different types of viruses: rhinovirus, adenovirus and even by some types of coronavirus (different from SARS-COV-2 that causes covid) and the flu due to the influenza virus. What happens with low temperatures is that the mucosa of the nose dries, becomes more fragile and therefore works worse as a barrier to the entry of these viruses.
On the other hand, as I told you at the beginning, viruses have a lipid coating that becomes more resistant with the cold. And in addition, hypothermia by itself, that is, the decrease in body temperature also partially reduces the proper functioning of the immune system. The protein that predominates in the mucosa is immunoglobulin A, if the virus is more resistant, if the nose becomes more fragile, then immunoglobulin A works worse. And if we add to that that the immune system itself loses some of its effectiveness, we have a situation that, indeed, causes an increase in colds, in autumn, and flu, in winter.
To all this we must add that when temperatures drop we spend more time in closed spaces with other people and that always favors the circulation of these viruses that spread by air from person to person. This is the same for common colds and the flu, but the flu comes later: in January or February, although some years earlier it is at the end of December.
It is not really the cold that affects directly, but the low temperatures cause a series of situations that are what cause the viruses that are transmitted through the respiratory tract to affect us more.
If this year we continue to use the masks indoors, it is very likely that there will not be a significant wave of colds and flu. But as long as we are careful, that we use the mask correctly, that we wash our hands and continue with the rest of the hygiene measures adopted to stop the COVID-19 epidemic. And, since they are transmitted in the same way, these measures also serve as a barrier for the viruses that cause colds and flu. It does not seem that the incidence is going to be as low as it was last year because we are already without a mask on the street and the capacity that is being allowed is practically 100%. And as much as the air is renewed, we should all wear a mask. The terraces are also another source of contagion because we are very close to each other and we take off our masks to eat and drink and even to talk, and then they splash droplets. In my opinion, we should continue to wear a mask until at least March. If we do it like this, there will continue to be flus and colds, but the transmission will decrease. It is a way to put physical barriers to viruses that is very effective and can significantly reduce the number of common colds and flu.
