CNN
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The updated Covid-19 boosters are cutting the risk that a person will get sick from the coronavirus by about half, even against infections caused by the rapidly spreading XBB.1.5 subvariant.
New studies, conducted by researchers at the US Centers for Disease Control and Prevention, are among the first looks at how the bivalent boosters have continued to work in the real world as the virus has evolved. The data shows that the boosters are continuing to offer substantial protection against currently circulating variants.
The near-real-time data was collected by the federally funded Increased Community Access To Testing program, which administers Covid-19 tests through pharmacies. It includes results for adults receiving tests at participating pharmacies from December 1 to January 13.
Of nearly 30,000 test results included in the analysis, more than 13,000 (47%), were positive for Covid-19.
More people who tested negative had gotten an updated bivalent booster compared with those who tested positive.
On average, people in the study who had not gotten a bivalent booster also had not had a dose of a Covid-19 vaccine in more than a year. That’s about the same as the national average, the study authors said. Their protection against illness was probably very minimal, they said.
The study results show that the updated boosters are most effective for younger adults.
For adults between the ages of 18 and 49, the boosters cut the odds of getting a symptomatic infection caused by the BA.5 subvariant by 52%, and it cut the odds of getting an infection caused by XBB or XBB.1.5 by 49%. For adults 50 to 64, the new boosters cut the odds of getting sick with Covid-19 by 43% for BA.5 and 40% for XBB subvariants. For those 65 and older, the boosters cut the odds of an infection with symptoms by 37% and 43% for the BA.5 and XBB subvariants, respectively.
Ruth Link-Gelles, a senior epidemiologist at the CDC and lead study author, said at a news briefing Wednesday that these vaccine effectiveness numbers are averages. Because everyone is unique in terms of their underlying health, their past exposure to the virus and other factors, these estimates of vaccine effectiveness may not apply on an individual level. She said it’s important to think of them on population level.
How long protection lasts
For people who are wondering whether the protection from the bivalent booster they got in September has worn off by now, it’s too early to know how waning would work with these new two-strain shots, Link-Gelles said.
So far, there’s little evidence of waning effectiveness two to three months after people got their shots.
“It’s too early, I think, to know how wani …