Moderna vaccinates first participant in phase 2 trial of Omicron-specific booster as study finds that antibodies fall 6-fold over 6 months

“We are reassured by the antibody persistence against Omicron at six months after the currently authorized 50 μg booster of mRNA-1273. Nonetheless, given the long-term threat demonstrated by Omicron’s immune escape, we are advancing our Omicron-specific variant vaccine booster candidate and we are pleased to begin this part of our Phase 2 study,” CEO Stéphane Bancel said in a news release. “We are also evaluating whether to include this Omicron-specific candidate in our multivalent booster program.”

Moderna promises to share its data from the trial with public health leaders so they can make evidence-based decisions on the best booster strategy against the coronavirus going forward.

Covid pandemic 'nowhere near over,' WHO says

Omicron currently accounts for 99.9% of US Covid-19 infections, the US Centers for Disease Control and Prevention said Tuesday. The Delta variant makes up the remaining 0.1%.

A study published Wednesday says the Moderna Covid-19 booster shot remains durable against the Omicron variant, but the antibody protection wanes and is six times lower six months after getting boosted.

The study, published in the New England Journal of Medicine, also found that the neutralizing antibody levels declined against the Omicron variant much more rapidly than against the dominant strain of the virus that was circulating two years ago.

Research teams from Moderna, Duke University, Emory University, the Fred Hutchinson Cancer Research Center, the Baylor College of Medicine, the University of Maryland School of Medicine and the National Institutes of Health looked at blood samples from adults who had two doses of the Moderna vaccine, as well as those who also had a booster dose. Some of those were boosted with the 50-microgram dose and some at 100-μg levels. The current booster is authorized at the 50-μg level.

With the primary two-dose regimen, the Moderna vaccine generated neutralizing antibodies against the Omicron variant in 85% of the people in the trial one month after the second dose.

Seven months after the participants got their second dose, neutralization against Omicron was detected in only 55% of the blood samples.

A 50-μg booster dose improved the durability of neutralization at 20 times higher than the levels seen in those who just got two doses of the vaccine.

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