Third dose, booster dose or booster dose: whatever its name, this additional injection will be essential to continue to have your health pass. From December 15 for those over 65, and from January 15 for others. What push the crowds to look for a niche. Finally, the crowds minus a few skeptics who are cautious about receiving an extra dose.
In the midst of the wave of the fifth wave of coronavirus, this reminder is intended to boost our immunity by ordering our body to relaunch the production of protective antibodies. But can we make too many antibodies? Does this third dose cause more side effects than the previous ones?
How well does the booster dose boost immunity and can it generate too many antibodies?
With 60,000 daily contaminations recorded on average in recent days and infections (not very serious) observed in people who have yet a complete vaccination schedule, this fifth wave shows that only a few months after receiving the anti-Covid vaccine, our antibody levels have declined too much to prevent the outbreak. This wave prompted health authorities to speed up the recall campaign for all. “The available data support the safe and effective administration of a booster dose as early as three months after the end of the primary vaccination if such a short interval is desirable from a public health point of view,” Marco said on Thursday. Cavaleri, head of vaccine strategy at the European Medicines Agency (EMA), who so far recommended waiting six months.
A recent study of the Directorate of Research, Studies, Evaluation and Statistics (DREES) demonstrates the effect of this booster dose. “For people over 60 years of age whose full status dates back more than six months, (she) improves vaccine protection to around 95%” and “greatly reduces the risk of hospitalization”. And according to another study pre-published on the platform
Medrixv, it also helps prevent infection and thus break the chains of transmission. “There is absolutely no risk in having a large amount of antibodies, especially since they are doomed to decrease over time”, reassures Lionel Barrand, president of the union
Medical biologists.
In addition, a few weeks after the discovery of the Omicron variant, whose mutations could make it more resistant to vaccines, having a lot of antibodies is rather an asset. “Omicron is a variant that escapes antibodies much more,” said Ugur Sahin, CEO of German BioNTech and partner of Pfizer on Wednesday. This new strain is therefore “probably not sufficiently neutralized after two doses”, recognized the same day the German-American duo, which is working on an updated version of its serum. But “the vaccine is still effective against Covid-19 if it has been administered three times”, they assure in a press release based on studies not yet published.
What are the protective thresholds? Would there be any interest in taking an antibody test before receiving your booster dose?
“We have known for a while to identify the presence of antibodies in the blood, but it remains difficult to precisely assess the protective thresholds against infection. We are more on estimates, tempers the biologist. Not to mention cellular immunity, which we do not measure today, but which has a very important role. I have a lot of patients who tell me: “I have a very high level of antibodies”, at 300 or 500 units, but that does not mean anything. Less than two weeks after an injection, this rate can be as high as 40,000. So, especially no light interpretation, it is useless, it would even be dangerous. If you have a high level of antibodies, so much the better, that’s what you are looking for. On the other hand, this should not define the vaccination strategy, and should in no case serve as a basis for the idea that a booster dose would not be necessary. Today, the antibody level does not in itself provide any usable information, ”insists Lionel Barrand.
“There is not yet any data making it possible to define correlates of protection, that is to say the existence of a level of protection in relation to a measured level of antibody”, abounds in the High Authority of Health.
Are there more side effects after the booster dose compared to the previous doses?
More pain at the injection site, a higher fever: some describe stronger side effects after this reminder. Many factors can explain more or less strong reactions depending on the individual. “It also depends on the immunity of each: a person who has a weak immunity often has less effects after the vaccine because it defends itself less”, notes Lionel Barrand. This is what explains why, before the booster dose, immunocompromised people needed a third dose to have a complete vaccination schedule, against two in the general population.
“The inflammation generated by the vaccine can cause symptoms, it’s quite common. But if the effects felt are stronger, it is not because we would produce too many antibodies, but because the organism has already been stimulated against the virus, insists the biologist. It makes sense to have more effects after the second or third dose than after the first. There is nothing to worry about ”.
Thus, with the Pfizer-BioNTech serum, “no specific signal was identified in people who had a booster dose. The profile of reported adverse effects is similar to that reported (…) at the start of the campaign, ”reassures the ANSM. Ditto for Moderna: “No specific signal has been identified concerning the booster doses and the third doses”.
While to date in France, more than 12 million people have received their recall, the Minister of Health, Olivier Véran, “wishes that we are 20 million eligible to have had it by Christmas. The current dynamic allows us to hope so, ”he said on Friday. Such an objective would constitute according to him “a real achievement”, and would imply continuing to “be at 500, 600, 700,000 booster vaccinations per day”.