With the gradual lifting of certain sanitary restrictions, particularly at the level of barrier gestures, the resurgence of winter viruses is to be expected, and this as early as this summer. In any case, this is what several experts told our colleagues from the New York Times.

Summer colds: why we're especially likely to get them this summer

It's late July, the middle of summer, and yet you have a cold. Your Covid-19 test is negative. Could it be a simple cold in the middle of summer? It's very likely, say several experts to our colleagues of the New York Times.

Surprisingly, while the Covid-19 pandemic had overshadowed the winter viruses (rhinovirus and flu in the lead), these viruses could well reappear this summer, despite the milder temperatures.

There are several reasons for this resurgence of usually winter viruses, starting with the gradual lifting of certain barrier measures, such as wearing a mask outdoors. The return to a richer social life, with gatherings, events and more frequented public places, also allows a certain promiscuity conducive to the spread of viruses.

An untrained immune system

Moreover, while our immune system was once trained to fight winter viruses and encounter many pathogens, it has just spent several months without being exposed to them. Clearly, it is out of practice. It may then need more time to reactivate itself against a simple cold virus

 "Frequent exposure to various pathogens primes or stimulates the immune system to be ready to respond to that pathogen," said Paul Skolnik, MD, immunovirologist and chair of internal medicine at the Virginia Tech Carilion School of Medicine, USA. "If you haven't had those exposures, your immune system may be a little slower to respond or may not respond as fully, resulting in greater susceptibility to certain respiratory infections and sometimes longer or more prolonged symptoms," he added.

According to the New York Times, this return of common respiratory viruses is already observed in the United States, but also in Europe and even in the southern hemisphere, in Australia and New Zealand in particular. Some young, fragile children have even had to be hospitalized because of severe symptoms.

 "I haven't seen anything like this in my 20 years as a virologist," said Dr. Sue Huang, director of the World Health Organization's National Influenza Centre at the New Zealand Institute of Environmental Science and Research. "There is usually some degree of pre-existing immunity because of the previous winter. When you don't have that kind of protection, it's kind of a drag. The fire can progress and the chain of transmission continues," she added.

Experts call on everyone to continue to follow barrier practices, including hand washing and sneezing into one's elbow, both to fight Covid-19 and to prevent the spread of conventional respiratory viruses. They also believe that vaccination against Sars-CoV-2 is a simple way to be less paranoid about the slightest runny nose...