In a new study from the Ragon Institute of MGH, MIT and Harv, researchers found an additional “booster” dose of Moderna or Pfizer mRNA-based vaccine is needed to provide immunity against the Omicron variant.
The results suggest that traditional dosing regimens of COVID-19 vaccines available in the United States do not produce antibodies capable of recognizing and neutralizing the Omicron variant.
In the study, the team evaluated the effectiveness of the three COVID-19 vaccines available in the United States, which include the two-dose Pfizer and Moderna injections and the one-dose Johnson & Johnson vaccine.
They also examined blood samples from 239 individuals who had been fully vaccinated with one of the three COVID-19 vaccines.
Included in this group were 70 men and women who had received a third booster dose of either the Pfizer or Moderna vaccine.
The blood samples were used to measure how effectively each vaccine induces the production of protective immunity in the form of antibodies against the Omicron pseudovirus, as well as the Delta and wild-type viruses.
The results were striking. The team found very little neutralization of the Omicron variant when they used samples taken from people vaccinated with two doses of mRNA vaccine or one dose of Johnson & Johnson
But people who received three doses of the mRNA vaccine had very significant neutralization against the Omicron variant.
It’s not yet clear why an mRNA booster dramatically improves immune protection against Omicron, but the team says one possibility is that an additional dose creates antibodies that bind more tightly to the spike protein, increasing their effectiveness.
Also, a booster dose may generate antibodies that target regions of the spike protein that are common to all forms of SARS-CoV-2. Both theories may be true.
The team notes that the three-dose mRNA vaccine regimen—that is, the traditional two doses and a booster of Pfizer or Moderna vaccines—provides somewhat lower levels of neutralizing antibodies against Omicron than it does against the COVID-19 wild type strain or Delta variant.
But the study’s results strongly support the CDC’s advice that COVID-19 booster shots are appropriate for anyone 16 and older, and that mRNA vaccines are preferred.
If you care about Covid, please read studies about most effective face-mask practices to reduce spread of COVID-19, and when is it OK to take a rapid antigen test for COVID rather than lining up for a PCR swab.
For more information about health, please see recent studies about common drugs that could treat COVID-19, and results showing that are some foods super bitter to you? You may have lower COVID-19 risk.
The study is published in Cell. One author of the study is Alejandro Balazs, Ph.D.
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