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Moderna’s two-dose COVID-19 vaccine is less effective against the new Omicron variant, according to a new preprint study published Wednesday. The study hasn’t been peer-reviewed or published in a journal.
But a booster shot of the Moderna vaccine increased antibodies that were highly effective at blocking Omicron.
“The antibodies that people make after they get the standard two inoculations of the Moderna mRNA vaccines are 50 times less effective against Omicron than they are against the original form of the virus,” David Montefiori, PhD, the senior study author and a virologist at Duke University Medical Center, told NPR.
“What these results are telling us is that if Omicron becomes a dominant variant, it’s going to become even more important that people get their boost,” he said.
Montefiori and colleagues tested antibodies in blood samples of vaccinated people against a pseudovirus, a viral particle that is not considered a live virus, which was created in a lab to mimic the mutations on the Omicron variant. They studied blood samples from 30 people who had gotten two Moderna shots and found that antibodies were about 50 times less effective at stopping the Omicron variant.
The research team also studied blood samples from 17 people who had received a Moderna booster and found that the extra shot was helpful. The booster was about as effective at blocking the Omicron variant as it was at blocking the Delta variant.
The findings are similar to other studies of blood samples from people who have received Pfizer’s COVID-19 vaccine. The two-shot series was less effective against Omicron, but a third shot helped to boost antibodies.
Based on the results, Montefiori said a new vaccine that specifically targets the Omicron variant won’t be needed, NPR reported.
Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, shared the same message during a White House COVID-19 briefing on Wednesday — for both the Moderna and Pfizer vaccines.
“Our booster vaccine regimens work against Omicron,” he said. “At this point, there is no need for a variant-specific booster.”
Scientists are also testing the Omicron variant against the Johnson & Johnson vaccine alone and with a Pfizer booster, NPR reported. Results are expected early next week.
The Omicron variant has been found in at least 36 states and 75 countries. It now accounts for about 3% of samples analyzed in the U.S., according to the latest CDC data, which is seven times the levels seen last week. In some parts of the country, such as New York and New Jersey, Omicron makes up about 13% of cases.
The Omicron variant could become the dominant form of the coronavirus in the U.S. within weeks, public health officials said this week.
“We could be facing very severe surges, very severe strains on our health care systems under the worst-case scenarios,” Lauren Ancel Meyers, PhD, a researcher at the University of Texas at Austin, who has been modeling the potential effects of the Omicron variant in the U.S., told NPR.
“I’m worried,” she said. “We don’t want to be caught unprepared.”
MedRxiv: “Booster of mRNA-1273 Vaccine Reduces SARS-CoV-2 Omicron Escape from Neutralizing Antibodies.”
NPR: “Omicron evades Moderna vaccine too, study suggests, but boosters help.”
C-SPAN: “White House COVID-19 Response Team Briefing,” Dec. 15, 2021.
CDC: “COVID Data Tracker: Variant Proportions.”
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