Is there still time to get a flu vaccine?

That's it, the flu is making a comeback. Influenza viruses have even taken hold since almost all metropolitan regions are now in an epidemic phase, according to the latest report from Public Health France. As every year, vaccination is recommended for health professionals and even more so for people at risk of developing a serious form. This mainly concerns people aged 65 and over, people who are obese or suffering from certain illnesses (chronic respiratory diseases, cardiovascular diseases, diabetes, etc.) and pregnant women. This year, the vaccination campaign started on October 17. With the epidemic already off to a good start, is there still time to get vaccinated? Is the vaccine effective? And why do we have to do it again every year? Answers with two specialists.

Influenza viruses have the particularity of constantly evolving, sometimes with the appearance of genetic mutations. “From the moment a virus infects a person, it will mutate as it multiplies in the body, in particular to escape immune defenses,” explains Vincent Enouf, deputy director of the National Reference Center for Human Viruses. respiratory infections.

This characteristic requires the composition of the vaccine to be adjusted each year to introduce the four most recent viral strains in circulation. So get vaccinated every year.

Especially since the protection conferred by the vaccine only lasts around six months. “From the moment you are vaccinated, the immune system is ready. It will attack and eliminate the virus more quickly,” explains the respiratory virus specialist. Is there still time to do it for this season? “Yes, if it has not yet been done, it is urgent to do so because the epidemic has already started well,” underlines Sylvie van der Werf, professor at the Pasteur Institute in the virology department.

The vaccination campaign is not over, it is possible to be vaccinated until January 31. Knowing that the epidemic has just started, that a fortnight is necessary for protection to be effective and that a flu epidemic generally lasts 6 to 12 weeks, the game is still worth the effort. “But the ideal is to get vaccinated as soon as the doses are available in pharmacies,” insists Vincent Enouf.

Is the vaccine effective this year? “It’s a little early to say, we are only at the start of the epidemic so we don’t yet have a lot of virus to analyze,” replies Sylvie van der Werf. To develop the vaccine, “there are two meetings each year at the World Health Organization (one for the northern hemisphere, the other for the southern hemisphere) where the strains that should be part of the vaccine are decided. the composition of the future vaccine,” continues the specialist. A bet that viruses sometimes manage to foil, which explains the lower effectiveness of the vaccine in certain years. “But even average effectiveness protects serious forms,” Vincent Enouf would like to point out.

And the first data for the 2023-2024 vintage are rather reassuring. “The viruses currently circulating are mainly type A (H1N1), which is consistent with the vaccine,” says Vincent Enouf. Last year, the effectiveness of the vaccine was estimated at 44%. This means that a vaccinated person has halved their risk of developing a serious form, which is no small thing. “We consider that an effectiveness of 50% is very good for an influenza vaccine,” assures the deputy director of the National Reference Center for Respiratory Infection Viruses. As is the case with the Covid-19 vaccine, the flu vaccine does not necessarily prevent you from catching the virus and having symptoms. Its goal is to stop the virus before the infection escalates.

Some people fear the harmful consequences of a succession of anti-Covid and anti-flu vaccines. After all, don’t they say that “it’s the dose that makes the poison”? “Our immune system is constantly stimulated by everything we encounter, vaccines are just another encounter. To date, there are no reported or documented negative effects of these repeated vaccinations,” replies Sylvie van der Werf. “It is the infection which can give rise to the worst consequences, not the vaccination. There is a safe way to protect yourself from it, people at risk would be really wrong not to do so.”