The pharmaceutical company Moderna announced Tuesday that a new version of the company's COVID-19 vaccine appears to provide stronger, longer-lasting protection against variants of the virus than the original vaccine.
Preliminary results from a study testing a vaccine that targets both the original strain of the virus and the beta variant — a so-called "bivalent" vaccine — appears to produce high levels of antibodies for months that can neutralize the virus.
"We believe that these results validate our bivalent strategy," said Stéphane Bancel, Moderna's chief executive officer, in a news release.
Bancel added that another bivalent vaccine that combines the original strain with the omicron strain "remains our lead candidate" for a fall vaccination campaign aimed at protecting people against a winter surge. Results from the testing of that version are expect later this spring, according to Moderna.
"We believe that a bivalent booster vaccine, if authorized, would create a new tool as we continue to respond to emerging variants," Bancel said.
The study has not yet been reviewed by independent scientists and produced mixed reactions from outside experts.
"This paper is a 'proof of principle' that supports the concept of a bivalent mRNA vaccine," wrote Nathaniel Landau, a microbiologist at New York University, in an email to NPR. But Landau agreed a omicron-specific version would probably be the most useful.
Dr. Jesse Goodman, a former top Food and Drug Administration scientist now at Georgetown University, agreed the results are encouraging. But he also noted the approach needs to be confirmed by additional research.
"Other things could be at play in making the bivalent booster look better," Goodman wrote in an email to NPR.
John Moore, an immunologist at Weil Cornell Medicine, called the results "unimpressive" in an email to NPR. "What's here is unlikely to support the rollout of this type of bivalent vaccine — the benefits would not justify the expense and hassle."
Dr. Celine Gounder, an infectious disease expert at Kaiser Health News, said the company's announcement "seems misleading" because it compared the antibodies from just two doses of the original vaccine with a third dose of the new vaccine.
Researchers are testing several new versions of Moderna's and Pfizer's vaccines to see if they provide broader protection again the omicron variant. Federal officials are hoping to see enough results by later this spring to give companies enough time to produce enough vaccines for another round of shots in the fall, when immunity from previous vaccination and infections may be waning and another surge could be looming.
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