This study, funded by the National Institutes of Health (NIH), was eagerly awaited in the United States because it focuses on the possibility of “mixing” vaccines, that is, using a different vaccine for the dose. as a reminder that for the initial series which is not currently authorized in the country.
Carried out on 458 adults vaccinated with one of the three vaccines authorized in the United States (Pfizer, Moderna or Johnson & Johnson) for at least 12 weeks, three groups were each divided into three new groups, to respectively receive one of the three vaccines available as a booster dose. The nine groups in total therefore consisted of about 50 people each. The researchers then analyzed the antibody levels 15 days after the injection of the booster dose.
In people first vaccinated with Johnson & Johnson, antibody levels increased by 4 times after a booster dose of the same vaccine, by 35 after a booster of Pfizer, and by 76 after a booster of Moderna.
And the antibody levels of people first vaccinated with Moderna were each time higher compared to people first vaccinated with Pfizer or Johnson & Johnson, “regardless of the vaccine given for the booster dose”, according to this report. study. Another important point: “no safety problem was identified” after the administration of the reminders.
The study, which has not yet been peer-reviewed, has limitations, however. This is because the booster dosage of Moderna administered was 100 micrograms, which is double what the company is actually envisioning for its booster dose. In addition, the number of participants was reduced, and the immune reaction could evolve over time, beyond the 15 days observed in this setting. In addition, according to a study by Johnson & Johnson, a second injection about two months (56 days) after the first shows observed antibody levels which would be multiplied “by four to six”.
In the meantime, this study should feed into the discussions of an expert committee of the United States Medicines Agency (FDA). She is due to study the authorization requests for a booster dose from Moderna and Johnson & Johnson this Thursday and Friday.