People who have received the Covid-19 vaccine from Johnson & Johnson may benefit from receiving a booster dose of a different, messenger RNA vaccine, according to preliminary results from a US study, published Wednesday, October 13.
This study, funded by the National Institutes of Health (NIH), was eagerly awaited in the United States because it relates to the possibility of ” to mix together “ vaccines – that is, using a different vaccine for the booster dose than for the initial series – which is not currently allowed in the country.
The study was 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 twelve weeks. These three groups were each divided into three new groups, to receive respectively one of the three available vaccines as a booster dose. The nine groups in total therefore consisted of about 50 people each.
The researchers then analyzed the levels of antibodies, fifteen days after the injection of the booster dose. In people first vaccinated with Johnson & Johnson, antibody levels were quadrupled after a booster dose of the same vaccine, 35-fold after a Pfizer booster, and 76-fold after a Moderna booster.
“No security problem”
In addition, the antibody levels of people first vaccinated with Moderna were higher each time compared to people first vaccinated with Pfizer or Johnson & Johnson, and this “Regardless of the vaccine administered for the booster dose”, notes the study.
Furthermore, “No security problem has been identified” after the administration of the reminders, it is specified.
The study, which has not yet been peer-reviewed, has several limitations, however. First, 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 response could evolve over time, beyond the fifteen days observed here.
“It is important not to get carried away by these results”, warned, on Twitter, Peter Hotez, professor at Baylor College of Medicine. The results of Johnson & Johnson’s second-dose booster trials conducted by the company itself over a longer period were “Impressive”, he recalled.
The NIH study should in any case feed the discussions of a committee of experts from the United States Medicines Agency (FDA), which must study the authorization requests for a booster dose of Moderna and Johnson & Johnson , Thursday and Friday, respectively. A booster of Pfizer’s vaccine is already authorized in the country for certain categories of populations.
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