(New York) – An early look at the performance of recent COVID-19 booster shots Omicron wave in the US suggests a reduction in effectiveness, although the injections still offer strong protection against severe disease.
The report, released by the Centers for Disease Control and Prevention on Friday, is considered an early and limited look at the durability of enhanced protection during the explosive Omicron surge in December and January but has fading in recent weeks.
“COVID-19 vaccine boosters remain safe and continue to be highly effective in combating serious illness over time,” said Kristen Nordlund, a CDC spokesperson.
[time-brightcove not-tgx=”true”]
The researchers looked at patient visits to hospitals and urgent care centers in 10 states. They estimated how effectively the booster shots Pfizer or Moderna prevented COVID-related visits to emergency departments and urgent care centers, and how effective the vaccines were. prevent hospitalizations.
Read more: There is good reason to be optimistic about Omicron
About 10% of people in the study were motivated. The vaccine’s effectiveness was higher in people who received a booster shot than in those who received only the initial series of shots.
But the researchers also found that during the time when the Omicron variant was dominant, the vaccine’s effectiveness for outpatient visits was 87 percent in those who had had a booster shot two months earlier, but 66% four months later. The vaccine’s effectiveness against hospitalization decreased from 91% after two months to 78% by the fourth month.
However, those results were based on only a small number of patients – less than 200 – who had been promoted four months earlier at the time of the Omicron wave. And it’s not clear whether those people taking early risers for medical reasons could make them more susceptible to severe illness.
The study notes that the post-boost effect was higher last year, when the Delta variant caused most cases in the US.
Health professionals expect protection from vaccines to wane. The evidence-based US push-up campaign emerged last year showing that vaccine protection fades six months after people got their initial vaccination.
And from the outset, the vaccine provided less protection against the Omicron mutation than earlier versions of the virus. The study could not resolve how the protection would resist the next variant.
The new study’s findings are still remarkable, said Dr. William Schaffner, a vaccine expert from Vanderbilt University.
“I am a bit surprised, given the data, that it has already started to wane,” he said, adding that he would expect higher estimates of vaccine effectiveness at the four-month mark after the booster shot.
But Schaffner also said he’d like to see more research on surge protection’s durability, adding that “let’s look at this with a grain of salt.”
Dr Michael Saag, an infectious disease physician at the University of Alabama at Birmingham, said 78 per cent effectiveness against hospitalization was “still quite effective”.
“Anecdotally, I’ve seen very few people die from strengthening their health,” he said, even among people with weakened immune systems. “The vaccines are still working.”
___
Washington-based AP medical writer Lauran Neergaard contributed to this report.
