FDA Weighing Dose Of Moderna Covid-19 Booster
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The Food and Drug Administration is considering whether to authorize a lower dose of Moderna Inc.’s Covid-19 vaccine for boosters than the dose given in the first two shots, people familiar with the deliberations said. Moderna said it is asking the FDA to authorize a 50 microgram dose, half the dosage of the first two shots. Some in the government are leaning toward authorizing the 100 microgram dose, the people said, because of concerns a lower-dose booster might not offer a durable enough boost to counter fast-changing variants of Covid-19.

No final decision has been made, the people said, as the FDA is still reviewing data from studies that tested boosters using the different doses. People who have seen the data said both doses produce a strong immune response. Complicating the decision is the FDA has limited comparative data on which to base their choice, one person familiar with the discussions said. The continuing deliberations are a reason the agency hasn’t yet authorized boosters, though the people expect a decision soon.

Last month, the Biden administration recommended that adults who got a messenger RNA vaccine from either Moderna or Pfizer Inc. and partner BioNTech SE start getting boosters this month. Johnson & Johnson’s vaccine is also expected to be included in the boosting strategy, after releasing the first results about its boosters last month. The company said it is engaging with the FDA.

There is no debate about the booster doses to administer for the Pfizer-BioNTech or J&J vaccines, the person said, though a decision on the J&J booster might take longer. Their boosters will be the same doses as the first shots. After initially spurning talk about boosters, federal health officials embraced the idea as the contagious Delta variant drove up case counts, even among some people who were vaccinated.

Also contributing to the change of mind was emerging but inconclusive evidence, from researchers in Israel and elsewhere, suggesting the molecular defenses triggered by vaccination wanes after several months. Whether boosters are needed remains up for debate. Some researchers say the evidence is insufficient, while the World Health Organization has urged giving shots to people in countries with limited supplies.

Moderna and the National Institutes of Health tested both 50 mcg and 100 mcg booster doses in clinical trials. Last month, Moderna released initial data showing that a 50 mcg booster strengthened antibodies against Delta and other variants of concern significantly higher than the levels after trial subjects received their two initial doses.