MAINTENANCE. “Infection with Omicron, without vaccination, the protection is not sufficient”

“I have had all my vaccinations. The last (reminder) on December 1, 2021. On December 10, I tested positive for Covid-19. Should I consider this a fourth dose? †asks François.

According to the latest recommendations from the Ministry of Health, a Covid-19 infection is equivalent to a vaccine injection. However, it all depends on when you were infected: more than three months after your booster, or less than three months.

“If the infection has occurred more than three months after the first booster, a second booster is not necessary. Indeed, the occurrence of an infectious episode triggers an immune response at least equivalent to that of a booster vaccine.we read on the website of the Ministry of Health.

And “If the infection has occurred less than 3 months after the first booster, a second booster is needed. For people aged 80 and older, nursing home residents and USLDs or 6 months after infection for people aged 60 to 79, it is then advisable to wait at least 3 months after infection before performing the second booster vaccination »

So in your case, François, your infection is not equivalent to a new dose of vaccine because it occurred too soon after the injection of your booster vaccine, namely ten days later.

Also read: COVID-19. Is the fourth dose mandatory? we answer you

To go further and understand whether an infection equals a dose of vaccine, we asked Yannick Simonin, virologist and research professor at the University of Montpellier. Maintenance.

Antibodies to Spike

What Happens in the Body During a Vaccine Injection or an Infection?

When someone is vaccinated or infected against Covid-19, the first reaction is a humoral reaction. The body then produces antibodies after a few days to block the virus from entering. Several weeks later there is the immune response which is a memory response. The cells prepare to respond again in the event of an infection.

In the case of Covid-19, RNA vaccines are effective because they stimulate both types of responses. There are vaccines that only stimulate the humoral response, for example inactivated vaccines, and thus probably the Sinovac vaccine. But in most cases, in Europe, with the vaccines used, we have this double stimulation.

What about the quality of the immune response, either to infection or to vaccination?

There are actually different immune responses. With vaccination, the antibodies are directed against the Spike protein, while with a Covid infection the body develops antibodies that also go against other proteins of the virus.

During vaccination, the developed antibodies are more numerous and more effective against Spike, after an infection the antibodies also go against other parts of the virus, which can be compared to a thinning of the immune system. He doesn’t just fight the Spike protein.

Also read: COVID-19. I was infected after my third dose, am I well protected?

Being infected with Omicron, but not being vaccinated, is not sufficient protection.

—Yannick Simonin

When do you get the best protection?

With the Omicron variant, the data suggest that people are better protected after vaccination than after infection. Very often we are better protected with an infection, but here with this variant vaccination would be more effective.

The best protection corresponds to a vaccination, two doses, followed by an infection. There the antibodies are more important and more stable over time. Both doses of vaccine reduce the intensity of symptoms.

Two doses or three doses followed by an infection is where the best stimulation is obtained. Being infected with Omicron, but not being vaccinated, is not sufficient protection.

Also read: COVID-19. Incubation, infectivity, symptoms: what have the Omicron variants changed?

Protected for how many months?

So does this meet the Ministry of Health’s recommendations on vaccination? The ministry explains that in some cases an infection can replace a booster shot.

Yes that is it. But a person who is only infected, who has not been vaccinated, cannot be considered a dose of vaccine.

What is the knowledge about the duration of protection of vaccines?

Protection against symptomatic forms is estimated at 4-5 months after the vaccine dose, after that it becomes weaker, but protection against severe forms is still there, around 80%.

Hence a fourth dose for the over 60s that can increase protection levels. There may be an incentive for a booster dose in the general population at the start of the school year in September, but this depends on the variants in circulation at that time.

Also read: COVID-19. A sharp drop in the number of cases observed in France: what can we expect for this summer?

In the coming months we will enter a period of rest. We have a swimming pool immune responses in the population: people who have been fully vaccinated, those who have been vaccinated and then infected, those infected with different variants … But a person who has never been vaccinated and infected with Omicron has only weak protection.

MAINTENANCE. “Infection with Omicron, without vaccination, the protection is not sufficient”

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