Omicron-Specific Booster Trials Are Now Underway

The first participant has received a shot in Moderna's Phase 2 clinical trial of an omicron-specific vaccine booster. Moderna, which made the announcement Wednesday, expects to enroll 600 adults in the US study, including some who have already received a booster shot, per Reuters. "We are reassured by the antibody persistence against omicron at six months after the currently authorized 50 μg booster of mRNA-1273," CEO Stéphane Bancel said, per CNN. "Nonetheless, given the long-term threat demonstrated by omicron's immune escape, we are advancing our omicron-specific variant vaccine booster candidate." Pfizer and BioNTech announced Tuesday that they were also beginning trials of a coronavirus vaccine booster specific to omicron, which could be ready by March, per CNBC.

Moderna's announcement comes as a new study, published in the New England Journal of Medicine, shows antibody protection against omicron drops significantly six months after Moderna's initial vaccine shot. Two doses of vaccine resulted in detectable neutralizing antibodies against omicron in 85% of participants after one month, but only 55% after seven months. A booster dose triggered a 20-fold rise in neutralization levels after one month, but that fell by 6.3 fold after six months, per CNN. Researchers said there was still "strong neutralizing activity." But the booster fared much better against the original strain of SARS-CoV-2, with a drop of only 2.3-fold after six months. Moderna said it would make evidence-based decisions on whether to include the omicron-specific vaccine in its booster program. (More Moderna stories.)