Health. How the Covid-19 made two viral strains of the flu “disappear”

Did the Covid-19 kill the flu? Not totally … but several strains came off the radar. And might even have completely disappeared, according to the most optimistic.

Many different viruses

These two strains are usually followed by epidemiologists year after year. But we have not heard from them since the start of the Covid-19 pandemic.

Since March 2020, the journal STAT tells us, two strains of the A / H3N2 virus and the B / Yamagata line have no longer been detected. Are they off, due to lack of active traffic, or only out of the radars? Overall, there is great hope, but caution remains in order:

I think there is a good chance that the H3N2 virus is gone. But the world is big …

Trevor Bedford, Fred Hutchinson Cancer Research Center de Seattle

Just because no one has seen it doesn’t mean the B / Yamagata virus is gone, is it? But indeed, he could see disappeared

Florian Krammer, Icahn School of Medicine Mount Sinai de New York

Massive brakes on the spread of viruses

Richard Webby, in charge of studies on the ecology of influenza in animals and birds at the WHO, thinks for his part that there has indeed been a great reduction in the diversity of these viruses in circulation, but that they have not completely disappeared.

Why? The Covid-19 pandemic would have a lot to do with it: successive confinements, reduction in international trade, masks, hand washing and physical distance have not slowed down the spread only of Sars-Cov-2.

However, without human “hosts” to infect, viruses disappear: unlike bacteria, they cannot survive on their own.

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The seasonal flu remains very far from the terrible toll of Covid-19 (650,000 deaths per year for the flu, clearly more than 3 million for the Covid).

A universal vaccine in sight?

The very nature of influenza viruses prevents the development, so far, of a universal vaccine, which would target all strains. But if some of the more common ones were to disappear, the challenge might be more attainable.

During the season – shortened by the Covid – 2019/2020, the flu killed 4,000 people in France, against 6 to 10,000 on average in other years.

Vaccination, when it is more important, greatly reduces influenza mortality. But immunization coverage is too low each year according to health authorities. And this, despite the free vaccine for people at risk.

It is because of the multiplicity of viral types, subtypes and strains that vaccination against influenza is necessary each year: the vaccine produced against one is not effective, or not enough, against another variant of the virus. virus.

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