Booster shot needed to protect against Omicron, lab study finds
Chelsea, Mass. (Photo from Robert Wood Johnson Foundation)
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A booster shot of the Moderna or Pfizer-BioNTech vaccine is needed to provide immunity against the Omicron variant of the coronavirus, according to a study just reported in the peer-reviewed journal Cell.
The study “indicates 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,” report the researchers, from the
Ragon Institute of
Massachusetts General Hospital,
Harvard University and the
Massachusetts Institute of Technology.
The researchers created a harmless “pseudovirus” version of Omicron to evaluate the laboratory effectiveness of the three Covid-19 vaccines available in the U.S., which include the two-dose Pfizer and Moderna messenger RNA vaccines and the one-dose Johnson & Johnson injection.
They obtained blood samples from 239 people in Chelsea, Mass., just north of Boston, who had been fully vaccinated with one of the three vaccines. The group included 70 who had received a third dose of the Pfizer or Moderna mRNA vaccine.
“The results were striking,” the researchers report. “We detected very little neutralization of the Omicron variant pseudovirus when we used samples taken from people who were recently vaccinated with two doses of mRNA vaccine or one dose of Johnson & Johnson,” says Balazs. “But individuals who received three doses of 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,” they report, but “one possibility is that an additional dose creates antibodies that bind more tightly to the spike protein” that attaches to human cells, causing the infection. Also, a booster dose may generate antibodies that target regions of the spike protein that are common to all forms” of the virus.Three doses of mRNA provide “somewhat lower levels of neutralizing antibodies against Omicron than it does against the Covid-19 wild type strain or Delta variant,” the researchers report. “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.”