A priori, giving a different vaccine as a booster boosts the antibodies even better. Many people eligible for the Covid-19 vaccine booster, and vaccinated by Pfizer / BioNTech’s Comirnaty, received Moderna’s Spikevax as a third dose.
On Friday, the High Authority for Health (HAS), which had not validated this procedure, alerted the health authorities so that they stick to Pfizer for the time being. Indeed, Moderna’s serum has not yet received a favorable opinion from the European Medicines Agency (EMA) for this booster dose. The government immediately indicated that it would follow this advice.
Doubts about the right target population
The suspension, by several Scandinavian countries, of the injection of the Moderna vaccine for certain categories of the population, has fueled suspicions and orders not to take legal risks.
At the end of the week, these countries had not yet transmitted to the EMA the studies showing an increased risk of myocarditis and pericarditis (none of which, however, would have had prolonged effects). But beyond these side effects, there are still doubts about the right target population and “Especially the dosage”, raises the HAS.
Moderna’s vaccine has three times more active substance than Pfizer. Should I inject a full dose or a half dose as a booster? The European Medicines Agency should position itself by the end of October.
Until then, Moderna’s Spikevax – the vaccine which currently delivers the most numerous – will have to remain limited to primary vaccinations (between 40,000 and 45,000 per day, all vaccines combined, last week) or to second doses. (between 100,000 and 150,000 daily).