Moderna says COVID-19 booster shot appears effective against Omicron

The company states the booster shot significantly increased levels of immune-system antibodies against Omicron.

Moderna said on Monday that laboratory testing showed that a booster dose of its COVID-19 vaccine was protective against the fast-spreading Omicron variant, and that the current version of the shot will remain its "first line of defense against Omicron." The decision to focus on the current vaccine, mRNA-1273, was influenced in part by the speed with which the recently identified variant is spreading, according to the vaccine developer. Dr Paul Burton, Moderna’s chief medical officer said, “What we have available right now is 1273. It’s highly effective and extremely safe. I think it will protect people through the coming holiday period and through these winter months, when we’re going to see the most severe pressure of Omicron.”

A two-dose course of the vaccine produced low neutralizing antibodies against the Omicron variant, according to the company, but a 50-microgram booster dose raised neutralizing antibodies against the variant by 37-fold.A higher, 100 microgram booster dose of the same vaccine drove antibody levels even higher - more than 80 times pre-boost levels. On a conference call, Moderna President Stephen Hoge stated that the business does not intend to pursue approval for the higher dose at this time. The antibody levels generated by the lower dose shot "are comfortably above" the levels that would signify a risk of 'breakthrough' infections for other variants of concern, Hoge said. U.S. regulators authorized the 50-microgram booster of Moderna's vaccine in October.