Flu, COVID-19, RSV: have health measures really weakened our immune system?

Flu, COVID-19, respiratory syncytial virus (RSV): many viruses are currently circulating in Quebec, which makes some people say that our immune system has been weakened by health measures. This is the concept of “immune debt”. But is it real?

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We take stock with Alain Lamarre, expert in immunology and virology at the National Institute for Scientific Research (INRS).

Are there more viruses circulating now than in the same period before the pandemic?

“It really depends on the viruses. For the respiratory syncytial virus (RSV), which affects children a lot, not only is the season early, but it is also strong. There are many cases. Generally, it is more around the holiday season that we see a marked increase in cases, ”says the virologist.

As for the flu, even if the season is early in the United States and in other provinces of Canada, the situation is still « fairly classic » in Quebec. As usual, the seasonal peak should be reached towards the end of December, despite an increase in cases in recent weeks.

How do you explain, then, that the hospitals of the province, and particularly those for children, are under so much pressure?

“Hospital capacity has greatly decreased in recent years. It lacks a lot of staff. I would therefore say that the shortage of labor in hospitals has something to do with it, ”says Alain Lamarre. He also recalls that cases of COVID-19 were already affecting the health system long before the arrival of other viruses.

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Is it true that sanitary measures have weakened our immune system?

« Not at all. The hypothesis of an immune debt, according to which our immune system is weakened and is more vulnerable to all sorts of things, does not hold water. There is no solid scientific data that allows us to believe it,” insists Alain Lamarre.

What is true, he nuances, is that as public health measures were increased, very few viruses circulated during the pandemic. Today, while the compulsory wearing of a mask and distancing are a thing of the past, certain viruses, such as HRV or the flu, are starting to circulate again.

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“Since we haven’t seen these viruses for two years, there is a greater chance that we will be infected, because our immunity goes down over time. It’s always like this: if we haven’t been around the flu virus for years, there is a strong chance that we will be infected when we encounter it again. It is for this reason that there are periodic vaccination campaigns. But it is our specific immunity against this pathogen that has diminished, not our entire immune system. It’s the same for RSV. This is an important nuance,” he explains.

Why are cases of RSV on the rise in children?

Here again, the increase in HRV infections in children is not a consequence of the weakening of their immune system, says Alain Lamarre.

“When young children start going to daycare, they are exposed to a lot of viruses for the first time. This is the reason why they are often sick during this period. But in the past two years, the measures in place have meant that children have been exposed to very little of the various viruses, including RSV. They don’t have the antibodies to fight it,” he explains.

Since more children than in the past are being exposed to the virus for the first time, the cases of infections, which would otherwise have been spread over two or three seasons, are exploding. Nothing to do, therefore, with their ability to fight the virus.

Should we go back to wearing the mask in public?

The immunology and virology expert believes that wearing a mask should be required when symptoms associated with one or other of these viruses appear.

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“The majority of the population is quite aware of what to do now. We have learned that these are effective measures to limit the spread of viruses, so it is a practice to keep. Moreover, it is a recommendation that common sense should be applied, not an obligation. If we have symptoms associated with a virus, wear it preventively,” he suggests.

Alain Lamarre also specifies that wearing a mask should not be prioritized over isolation, especially with young children, for whom wearing a mask is particularly difficult.

“If your kids have symptoms, don’t send them to school or daycare,” he concludes.

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