#INTERVIEW #case #infection #Omicron #vaccination #protection
“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? »Francois asks.
Indeed, according to the latest recommendations of the Ministry of Health, a Covid-19 infection is equivalent to a vaccine injection. However, it all depends on when you got infected: more than three months after your booster or less than three months.
“If the infection occurred more than three months after the first booster, a second booster is not necessary. In fact, the appearance of an infectious episode provokes an immune response at least equivalent to that of a booster vaccine.we read on the website of the Ministry of Health.
Y “If the infection occurred less than 3 months after the first booster, a second booster is necessary. So it is advisable to wait at least 3 months after infection, for people 80 years of age and older, residents of nursing homes and USLD, or 6 months after infection for people 60 to 79 years of age before doing the second booster vaccination. ».
Therefore, in his case, François, his infection is not equivalent to a new dose of vaccine because it occurred too soon after the injection of his booster vaccine, that is, ten days later.
Also read: COVID-19. Is the fourth dose mandatory? we answer you
To go further and understand if an infection is equivalent to a dose of vaccine, we asked Yannick Simonin, a virologist and research professor at the University of Montpellier. Interview.
Antibodies against Spike
What happens in the body during a vaccine injection or infection?
When one is vaccinated or infected against Covid-19, the first response is a humoral response. The body then produces antibodies after a few days to block the virus from entering. Then several weeks later there is the immune response, which is a memory response. The cells prepare to react again in case of 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, this is the case with inactivated vaccines, and therefore probably the Sinovac vaccine. But in most cases, in Europe, with the vaccines that are used, we have this double stimulation.
What about the quality of the immune response, either in case of infection or in case of vaccination?
Actually, there are different immune responses. With vaccination, the antibodies are directed towards the Spike protein, while with a Covid infection, the body develops antibodies that are also directed towards other proteins of the virus.
With vaccination, the antibodies developed 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 dilution of the immune system. It’s not just fighting the Spike protein.
Also read: COVID-19. I got infected after my third dose, am I well protected?
With Omicron, having been recently infected, but not vaccinated, is not enough protection.
When do you get the best protection?
With the Omicron variant, the data suggests that one is better protected after vaccination than after infection. Very often we are better protected with an infection but here with this variant the 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 you get the best stimulation. With Omicron, having been recently infected, but not vaccinated, is not sufficient protection.
Also read: COVID-19. Incubation, contagiousness, symptoms: what have the Omicron variants changed?
Protected for how many months?
Does this comply, therefore, with the recommendations of the Ministry of Health regarding vaccination? The ministry explains that an infection can replace a booster shot in some cases.
Yes, that’s it. But a person who is only infected, who has not been vaccinated, cannot be considered to have had a dose of vaccine.
What is known about the duration of protection provided by vaccines?
Protection against symptomatic forms is estimated at 4-5 months after the dose of the vaccine, then it weakens but protection against severe forms is still there, around 80%.
Hence a fourth dose for those over 60 years of age that allows increasing 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 will depend on the variants circulating at that time.
Also read: COVID-19. A sharp decline in cases seen in France: what should we expect this summer?
We are heading towards a period of calm in the coming months. We have a swimming pool immune responses in the population: people fully vaccinated, vaccinated and then infected, who have been infected with different variants… But a person who has never been vaccinated and becomes infected with Omicron will only have weak protection.