A two-pronged COVID-19 booster shot developed by Moderna sparks a stronger immune response against omicron and its subvariants than the original vaccine, the company said Monday, supporting the federal government’s decision to authorize the shot before the data were accrued.
In a press release, Moderna revealed the first results from human tests of the vaccine, now called mRNA-1273.222 and containing components that fight forms of omicron as well as the original coronavirus. The data show the level of virus-fighting antibodies generated by the new vaccine compared to the original, but not yet how well each shot protects against infection and disease.
The Food and Drug Administration granted an emergency use authorization for mRNA-1273.222 in August, before the results were available. The regulator based its decision on limited preclinical data, as well as trial results from a similar, but different reformulation of the company’s original shot. At the time, FDA officials noted that strain changes can be made without affecting safety. The agency also commonly reviews such changes for influenza vaccines, which get updated annually.
Still, Moderna’s shot, as well as a rival “bivalent” vaccine from Pfizer and BioNTech, were rolled out without knowing whether they are more protective than their predecessors. Data released by Pfizer earlier this month, and now from Moderna, suggest they might be.
Moderna’s data comes from a Phase 2/3 trial in which 511 previously vaccinated and boosted volunteers received either a shot of mRNA-1273.222 or the original vaccine, known as Spikevax. Levels of virus-fighting antibodies against the dominant virus strains in the U.S., BA.4 and BA.5, were five to six times higher in the volunteers who received the updated shot than in those who received Spikevax, meeting the study’s main goal, Moderna said.
The immune response observed was “consistent” between younger people and those age 65 and older, a group that’s particularly vulnerable to COVID-19’s worst health outcomes. The frequency of adverse reactions was “similar or lower” than what’s been seen with a second or third dose of Spikevax. No new safety concerns had emerged after up to three months of follow-up, Moderna said.
The data from Pfizer and Moderna could help with what’s so far been a lackluster booster campaign in the U.S. According to data from the Centers for Disease Control and Prevention, just 10% of people at least 5 years of age has received an updated booster shot.
Newly reported COVID-19 cases and deaths are well below the levels seen at the end of 2021 and beginning of 2022, when the first wave of omicron infections hit the U.S. Still, cases are expected to surge during the winter, an increase the new vaccines are intended to help blunt.