NEW YORK, Feb 12 (US): An early look at the performance of COVID-19-boosting shots during the recent omicron wave in the US hinted at a decline in efficacy, even though the shots still offer powerful protection against severe disease. The Press (AP) reported.
The report, published by the Centers for Disease Control and Prevention on Friday, is an early and limited look at the durability of the enhanced protection during the micron surge that erupted in December and January but has faded in recent weeks.
“Covid-19 vaccine boosters remain safe and will continue to be highly effective against severe diseases over time,” said Kristin Nordlund, a spokeswoman for the Centers for Disease Control and Prevention.
The researchers studied patients’ visits to hospitals and urgent care centers in 10 states. They estimated how successful vaccines from Pfizer or Moderna were in preventing COVID-related visits to emergency departments and urgent care centers, and how successful the vaccines were at preventing hospitalizations.
About 10% of the subjects in the study were boosted. Vaccine efficacy was higher in people who received boosters than in people who only received the original series of vaccines.
But the researchers also found that during the time when the omicron variant was dominant, the vaccine’s effectiveness against outpatient visits was 87% in people who got a booster dose two months earlier, but to 66% after four months. Vaccine efficacy against hospitalization decreased from 91% at two months to 78% by the fourth month.
However, these results were based on only a small number of patients–less than 200–who had been boosted four months earlier at the time of the omicron wave. It’s not clear if these people were given the early boosters for medical reasons that could put them at greater risk of developing serious illnesses.
The study indicated that efficacy after taking a booster dose was highest last year, when the delta variant caused the most cases in the United States.
Health experts expect protection from vaccines to wane. The US booster campaign built on evidence last year that vaccine protection was wearing off six months after people got their initial vaccinations.
From the start, vaccines offered less protection against omicron mutations than previous versions of the virus. The study could not address how the protection would hold up against the next variable to come.
Dr. William Schaffner, a vaccine expert at Vanderbilt University, said the results of the new study were remarkable.
“I am a little surprised, according to the data, that it is really starting to wane,” he said, adding that he had expected higher estimates of vaccine efficacy in the four-month period after booster.
But Schaffner also said he’d like to see more research on the durability of the enhanced protection, adding, “Let’s take this with a grain of salt.”
The 78% effectiveness against hospitalization is “still very effective,” said Dr. Michael Sag, an infectious disease physician at the University of Alabama at Birmingham.
“Through anecdotal evidence, I see very few people dying and being boosted,” he said, even among those with compromised immune systems. “Vaccines still work.”
AOQ
Attachment area