Three new CDC studies provide the first real-life data on the effect of boosters against Omicron, which now accounts for more than 99% of Covid cases in the US
This is the first real-life data to examine the effect of boosters against Omicron, which now accounts for more than 99% of coronavirus cases in the United States. The studies, released Friday, raise the question of whether people with just two vaccine doses should still be considered fully vaccinated.
“I think we have to redefine fully vaccinated as three doses,” said Dr. William Schaffner, a longtime CDC vaccine adviser who was not involved with the studies.
The studies have an enormous scope, involving millions of cases, hundreds of thousands of visits to emergency departments and urgent care centers, and tens of thousands of hospitalizations among adults.
Getting boosted was 90% effective at preventing hospitalizations during a period in December and January when Omicron was the dominant variant, according to a CDC study that looked at nearly 88,000 hospitalizations across 10 states.
In comparison, getting two shots was 57% effective when it had been at least six months past the second shot
Getting boosted was 82% effective at preventing visits to emergency rooms and urgent care centers, according to the study, which looked at more than 200,000 visits in 10 states.
In comparison, getting two shots was only 38% effective at preventing those visits when it had been at least six months past the second shot.
“I think it’s the third dose that really gives you the solid, the very best protection,” Schaffner said.
All three studies found that unvaccinated people faced the highest risks of becoming sick with Covid-19.
The CDC currently says a person is considered fully vaccinated after they’ve received their primary Covid-19 vaccines — two weeks after receiving their second dose of an mRNA vaccine, or two weeks after their first dose of the Johnson & Johnson vaccine. Booster doses are recommended for everyone age 12 and older five months after their primary vaccination series.
Less than half of those eligible to receive booster shots have gotten one, and only about a quarter of the total US population is fully vaccinated and boosted, according to CDC data.
Nearly 20% of the US population eligible to be vaccinated — those age 5 and older — has not received any dose of Covid-19 vaccine.
