Moderna Starts Testing Omicron Vaccine in People

The Cambridge, Mass., company didn’t provide a timetable for when results might be available, but its previous vaccine studies evaluating immune responses have generated preliminary results within about two months.

The start of Moderna’s testing, shortly after Pfizer Inc. and BioNTech SE began a similar study, brings vaccine makers and government officials closer to a thorny decision about whether to roll out an Omicron-specific vaccine.

While vaccine-company executives have said they think Omicron-specific boosters will be needed, U.S. government officials have been more cautious, saying current vaccines with boosters might be sufficient to protect against severe disease, even if they don’t stop infections.

Also, the current Omicron surge may fade by the time study results are known for the Omicron-specific boosters.

The Omicron variant now spreading around the U.S. and world has mutations that make it less susceptible to immune-system antibodies induced by Moderna’s original vaccine, mRNA-1273, also known as Spikevax.

Moderna designed an Omicron-specific vaccine soon after the variant was identified in November.

Since then, Moderna and other researchers have run tests finding that the authorized booster shot of its original vaccine can restore protection against the Omicron strain.

“Nonetheless, given the long-term threat demonstrated by Omicron’s immune escape, we are advancing our Omicron-specific variant vaccine booster candidate,” said Moderna Chief Executive Stéphane Bancel.

Authorities may determine the Omicron-specific vaccine is warranted if the effectiveness of the original vaccine combined with a booster wanes significantly.

The booster is being tested in an extension of an ongoing middle-stage, or Phase 2, clinical trial that Moderna had previously started to test booster shots. Moderna is conducting the study at 24 locations in the U.S.

In one new portion of the trial, researchers will give a single booster dose of the Omicron-specific vaccine to about 300 adults 18 and older, at least six months after receiving the two-dose primary series of Moderna’s original vaccine.

A second group of 300 subjects, who have already received the third dose of Moderna’s original vaccine, will receive a booster dose of the Omicron-targeted shot at least three months after getting the original booster dose.

Researchers will track the safety of the Omicron-specific booster shot and whether it induces immune responses that are likely to be protective against disease caused by the variant.

Separately, a new analysis using blood samples from vaccinated people found that a booster dose of Moderna’s vaccine increased neutralizing antibodies against Omicron.

The antibody levels declined, but were still detectable six months after a booster shot, according to the analysis.

The analysis, conducted by researchers from Moderna, the federal government and academic labs, was published online Wednesday by the New England Journal of Medicine.

Write to Peter Loftus at [email protected]