Pfizer’s Covid Vaccine Protection Against Omicron Fades Just Weeks After Second And Third Doses, Study Finds

Immunity against the omicron coronavirus variant fades rapidly after a second and third dose of Pfizer and BioNTech’s Covid-19 vaccine, according to peer reviewed research published in JAMA Network Open on Friday, a finding that could support rolling out additional booster shots to vulnerable people as the variant drives an uptick in new cases across the country.

Levels of omicron-specific “neutralizing” antibodies—which can target the virus and stop it from replicating—decline rapidly after a second and third dose of Pfizer’s shot, according to the Danish study of 128 people who had received two or three doses.

Antibody levels, which are associated with protection against infection and disease, fell within weeks of getting the shots and were much lower than the level of antibodies specific to the original and delta coronavirus variants, the researchers said.

Compared to original and delta variants, the proportion of omicron-specific antibodies detected in participants’ blood dropped “rapidly” from 76% four weeks after the second shot to 53% at weeks eight to 10 and 19% at weeks 12 to 14, the researchers found.

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