The vaccine booster makes it possible to maintain a good level of protection against the coronavirus. In France, this booster (3rd dose or 2nd dose if we have had the Covid) is done with the vaccines from Pfizer or Moderna. But can you make a vaccine that is different from your initial vaccination schedule? What danger? The opinion of doctors.
[Mis à jour le 15 décembre 2021 à 10h35] Since December 15, people over 65 and people vaccinated with the Janssen vaccine must receive a booster dose to keep their health pass activated. In France, only so-called messenger RNA vaccines are given as a booster dose. It’s about vaccines from Pfizer and Moderna. This booster dose gives the immune system a “booster” effect and provides additional protection against Covid. But is it dangerous to recall with a vaccine different from the one we had for the first two doses? Receive Moderna vaccine after two doses of Pfizer? And the opposite ? Does mixing the vaccines provide a higher level of antibodies? On the contrary less important? Which vaccine to choose for the booster according to your age? Answers and explanations from Dr Mehdi Garaoui, general practitioner.
Which vaccine should you use as a booster?
In France, “the booster shots are performed only with mRNA vaccines (Pfizer-BioNTech or Moderna). Both of these vaccines can be used regardless of the vaccine used as part of the first vaccination schedule, but the Pfizer vaccine is recommended for people under the age of 30“, details the government. In a notice of November 8, 2021, the Haute Autorité de Santé thus recommends:
► For those under 30: to do his booster dose with the Comirnaty® vaccine (Pfizer). “In the population under 30 years old, the risk of myocarditis appears to be approximately 5 times lower for the Comirnaty® vaccine from Pfizer compared to the Spikevax® vaccine from Moderna (100 µg) in 12-29 year olds“, specifies the HAS in its press release.
► For those over 30: to do his booster dose with either the vaccine from Pfizer or the vaccine from Moderna. “The latter is particularly interesting for people at risk of severe form of Covid-19” notes the HAS which recommends the administration of a half-dose for the booster (50 µg of RNA instead of 100 in primary vaccination).
Can we mix anti-Covid vaccines?
“The side effect profile is the same with a hybrid regimen”
Yes, replies the Minister of Health Olivier Véran. It would not impact tolerance or efficacy. “I insist: Moderna and Pfizer, it’s the same. I say to French people who have had for example two doses of Pfizer and who are worried about having Moderna: no problem. Likewise, the French who have had Moderna twice and to whom we are going to offer Pfizer: no worries, it’s the same, he assured on December 3 on France Info. The only difference is that if you are under 30, we prefer to give you Pfizer rather than Moderna“. “Studies tend to show that hybrid schemes (Where heterologous) – by mixing vaccines of the same technology or of different technology – confer good protection, comparable to that of a vaccination schedule always using the same vaccine. So, regardless of the vaccine used in primary vaccination (an inactivated virus vaccine like AstraZeneca or Janssen, or a messenger RNA vaccine like Pfizer or Moderna), you can receive a booster dose indiscriminately with Pfizer or Moderna. There are no more side effects. The adverse reaction profile is the same with a hybrid regimen, confirms Dr Mehdi Garaoui. It would therefore be a shame to give up vaccination because we cannot necessarily have the same vaccine as in the primary vaccination.“.
| Public | 1st dose | 2nd dose | Booster dose |
|---|---|---|---|
| 12–17 years (immunocompromised, high-risk pathology or comorbidity) | Pfizer | Pfizer | Pfizer |
| 18 – 29 years old | Pfizer | Pfizer | Pfizer |
| 30 years and over | Pfizer or Moderna | Pfizer or Moderna | Pfizer or Moderna |
| People vaccinated with Janssen (single dose) | Janssen | Pfizer or Moderna (over 30 years old) | |
| People vaccinated with AstraZeneca | AstraZeneca | AstraZeneca, Pfizer, Moderna | Pfizer or Moderna (over 30 years old) |
| People who have had the Covid (therefore single injection) | Pfizer, Moderna, Janssen, AstraZeneca | Pfizer or Moderna (over 30 years old) |
Can the Moderna vaccine be made after Pfizer?
It is quite possible to receive a booster dose different from the initial vaccination course. If you have received one or two doses of Pfizer vaccine, you may be given a booster dose with Moderna. These two vaccines are based on the same technique: that of messenger RNA.
Can we do the Pfizer vaccine after Moderna?
Likewise, it is possible to receive a booster dose with Pfizer if the initial vaccination schedule was done with Moderna.
Can the Pfizer vaccine be done after AstraZeneca?
“Regardless of the inactivated virus vaccine administered as a primary injection, such as AstraZeneca or Janssen), one can receive a booster dose indiscriminately with Pfizer or Moderna “, answers our interlocutor.
Does mixing the vaccines have an impact on the antibody level?
Having a classic pattern or a hybrid pattern provides the same protection
“We should not think in terms of the rate or level of antibodies because there is no correlation between the amount of antibody that one has and the protection conferred. Dosage does not protect. In other words, it is not because we have a lot of antibodies that we are better protected against Covid. The important thing is to have neutralizing antibodies (specific antibodies that help prevent infection by blocking the entry of the virus into its target cells, as defined inInserm), whatever their rate. And so, having a classic pattern or a hybrid pattern brings the same level of antibodies neutralizers and thus provides the same protection“, reassures our interlocutor, confirming the statements of Prof. Alain Fischer, doctor, specialist in pediatrics and immunology and chairman of the Orientation Council for the vaccine strategy:”Receive a booster dose of Covid vaccine offers a very high level of protection in terms of neutralizing antibodies, both with Pfizer and Moderna“.”Evidence from heterologous vaccination studies suggests that the combination of viral vector vaccines (AstraZeneca and Janssen) and mRNA vaccines (Pfizer and Moderna) produces good levels of antibodies against the virus SARS-CoV-2 and a higher T cell response than using the same vaccine (homologous vaccination) whether in a primary or a booster regimen. Heterologous regimes have been generally well tolerated“, states the European Medicines Agency (EMA) in a press release dated December 7, 2021.
What are the risks if we mix anti-Covid vaccines?
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“There is no risk, would like to clarify Dr Garaoui. Mixing vaccines is not new and is not unique to the booster dose. The question already arose at the start of the vaccination campaign when we had bad signals for the AstraZeneca vaccine because of an increased risk of thrombosis. People under the age of 55, some of whom had had a primary injection with AstraZeneca, could no longer benefit from this vaccine and were switched to an injection of the messenger RNA vaccine (Pfizer or Moderna). At that time, studies had already analyzed the consequences of these hybrid vaccine schemes. These studies had shown that making an attenuated virus vaccine first, then a messenger RNA vaccine, gave good protection. We have therefore had a decline for several months on these hybrid schemesSo remember: mixing vaccines between doses does not decrease vaccine efficacy. “That’s okay, it’s like giving two treatments in the same therapeutic class, given in slightly different doses. Because that’s the main difference between the two vaccines. So we can do it“, says Dr Boris Hansel to BFMTV.
Thanks to Dr Mehdi Garaoui, general practitioner.