Three doses of Pfizer-BioNTech’s Covid-19 vaccine for the youngest children were 80 percent effective against the omicron variant of the coronavirus, according to early data the company released Monday.
The long-awaited findings bring the vaccine one step closer to a reality for parents of children ages 6 months to 4 years — the only group that remains ineligible for vaccination.
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Results from the company’s Phase 2/3 clinical trial also found that the vaccine — which uses a dosage one-tenth the level used for adults — generated a strong immune response and that it was safe.
The findings suggest that the low-dose vaccine “provides young children with a high level of protection against the recent Covid-19 strains,” Dr. Uğur Şahin, the CEO and a co-founder of BioNTech, said in the statement. “We are preparing the relevant documents and expect completing the submission process to the FDA this week.”
The 80 percent efficacy figure may change as the company gathers more data. It is based on 10 symptomatic cases of Covid that occurred seven days after the third dose of the vaccine as of April 29. A formal analysis will be performed once there are at least 21 positive cases in the clinical trial. The safety and immune response data are finalized, the company said.
The first two doses of the vaccine are given three weeks apart, followed by a third dose at least two months later.
The findings were announced in a news release, and the full data haven’t been made available for outside experts to review.
Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto, said that while the findings are “helpful,” more data about the vaccine in young kids are still needed.
“In the omicron era it does not appear that vaccine protection against infection is long-lasting,” he said. “It would be helpful to power studies to see the protective benefit from two versus three vaccine doses against severe infection, which is less common in this age cohort but can still happen.”
Dr. William Schaffner, an infectious diseases expert at the Vanderbilt University Medical Center, said that Pfizer's trial data may be too small to detect myocarditis, although he doesn't expect the inflammatory heart condition to be a problem for this age group. The mRNA Covid vaccines, from both Pfizer and Moderna, have been linked to a small but increased risk of the side effect in older teens and young adults.
Covid cases are once again on the rise across the U.S., including in children. The American Academy of Pediatrics reported 93,000 new cases in children during the week that ended May 12, up by 76 percent from two weeks before. Cases have been rising in children for the past five weeks, the academy said.
The rollout of a vaccine for the youngest age group — initially expected to begin by the end of 2021 — has hit a series of hiccups, leaving parents and pediatricians frustrated that the littlest kids remain ineligible for vaccination.
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In December, Pfizer said that two doses of the vaccine didn’t generate a strong enough immune response in 2- to 4-year-olds and that as a result, it would gather data on a three-dose regimen.
Even so, the company planned to submit the two-dose data to the Food and Drug Administration in February. The thinking was that the agency could at least begin the review process and potentially get kids started with the first two doses of the vaccine, knowing a third would be added later.
An advisory committee meeting to review the two-dose regimen, however, was postponed over concerns that the data were insufficient.
Moderna submitted its application for a vaccine for children under 6 at the end of April.
Dr. Doran Fink, a deputy director of the FDA’s division of vaccines, said at a public meeting Thursday that the agency is working to bring Moderna's request to its advisory committee as “rapidly as we can."
The FDA plans to convene its advisory committee on vaccines on June 15 to discuss the Moderna and Pfizer vaccines for young children.
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