Moderna and Pfizer boosters may protect against Omicron, find studies

Vaccines, and especially boosters, may protect against the worst outcomes of the highly contagious Omicron variant, new laboratory studies indicate.

At a World Health Organization meeting on Wednesday, scientists reported on research suggesting that T cells in vaccinated people can put up a tough defense against the variant, which could help prevent severe disease, hospitalization and death.

Dr. Anthony S. Fauci, US president’s top medical adviser for the coronavirus response, said two shots mRNA produced a negligible antibody response in the laboratory, but protection shot up after a third dose.

Others presented similar results, showing that mRNA boosters raised antibodies to levels believed high enough to offer strong protection against infection.

Though the research is preliminary and conducted in vitro, the news is nevertheless a welcome departure from the torrent of worrying data about Omicron, which can deftly evade antibodies, one reason infections may have exploded in many countries. But T cells also have a role.

Omicron infections are striking in those who have received shots, as well as those who aren’t vaccinated but have recovered from a coronavirus infection.

South African scientists said two doses of the Pfizer vaccine were 33 percent effective against Omicron, down from about 80 percent before Omicron.

The study found that two doses of the Pfizer vaccine offered 70 percent protection against death or severe cases requiring hospitalization, down from about 95 percent before Omicron was detected.

At the WHO meeting, one scientist after another presented similar findings showing that vaccine-induced antibodies performed less well against Omicron than against other variants.

Many countries are rushing to boost their populations’ immunity, but Omicron’s fast-spreading may well outstrip even the best efforts.

“The projected transmission rates, if borne out, do not give us much time for interventions,” Phil Krause, a former vaccine regulator at the Food and Drug Administration, said at the W.H.O. meeting.