The coronavirus vaccines most widely used in the United States remained highly effective at preventing the worst outcomes from infections even in the face of the highly transmissible omicron variant in January, a report released Friday by federal disease trackers shows.
While protection against mild illness waned over time, the mRNA vaccines from Moderna and Pfizer-BioNTech provided a robust shield against death and needing mechanical ventilation, the study from the Centers for Disease Control and Prevention found.
The study bolsters confidence in the vaccines to prevent the most serious outcomes for covid-19 patients, even after the omicron variant fueled an increase in cases, hospitalizations and deaths this winter, said William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, who did not participate in the study.
Although some fully vaccinated and boosted people came down with mild infections during the omicron surge, the study showed that the vaccines — and especially the booster shot — protected most people from the virus’s worst effects.
“Three doses was better than two — this report highlights the value of the third booster dose,” Moss said.
As omicron became the dominant variant, the vaccine was 79 percent effective in preventing ventilation or death for people who received the initial series of two doses. The benefit was even greater for people who received a booster shot: During that same time period, the vaccine was 94 percent effective for those people.
“Anybody who is skeptical really needs to look at that number and think, ‘Okay, maybe I’m going to get a cold and feel sick, but … I’m not going to get put on a ventilator or die,’” said Jeanne Marrazzo, director of the Division of Infectious Diseases at the University of Alabama at Birmingham.
The study comes as Pfizer and Moderna this week asked the Food and Drug Administration to consider authorizing a second booster shot following data published in Israel that showed vaccine effectiveness decreased as omicron surged. Pfizer requested the FDA allow adults 65 and older to get a second booster; Moderna asked regulators to authorize an additional booster for all eligible adults to allow flexibility for the CDC and health-care providers to determine which patients make good candidates for another dose.
If the FDA authorizes an additional booster shot, CDC advisers would weigh in on who should get the extra dose, and the CDC director would have the final say over those recommendations.