Latest news on Covid: vaccines, travel and more

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Credit…Alisha Jucevic for The New York Times

Outside advisers to the Food and Drug Administration voted Wednesday to recommend the agency authorize Moderna coronavirus vaccines for very young children, part of a much-anticipated review that could pave the way for regulators to release this week the vaccine or two. vaccines.

Panelists were scheduled to vote soon after on the same question for Pfizer-BioNTech’s vaccine for children under 5. Moderna’s vaccine is for children 6 months to 5 years old.

The FDA said data from the companies’ clinical trials show each vaccine met criteria for safety and effectiveness in the age group.

More than two years into the pandemic, no vaccines have been licensed for children under age 5 in the United States, an unmet need that has appalled many parents. If the panel recommends one or both vaccines, the FDA is poised to clear them as early as Friday.

Regulators and company officials spent much of the morning discussing side effects caused by the vaccine, the vast majority of which were mild and tolerated by children in clinical trials: irritability and crying, drowsiness, fatigue and loss of appetite. A smaller number of trial participants endured fevers, most of which did not exceed severe levels.

In younger age groups, fevers can be more debilitating and require more urgent medical attention, a dynamic that places significant pressure on manufacturers to calibrate dosage correctly. Pfizer chose a dose at only one-tenth the strength of the adult dose, given in three doses; the first two are given three weeks apart, with the third coming at least eight weeks after the second. Moderna used a quarter of the strength of its adult dose, given as two injections, four weeks apart.

Some difficult questions remain. Perhaps most importantly, neither vaccine has been tested against subvariants circulating in the United States. Clinical trials were largely conducted when the Omicron variant was prevalent. Two subvariants, BA.4 and BA.5, could become dominant within a month.

The need to protect these children from Covid is great, Dr. Peter Marks, the FDA’s lead vaccine regulator, said at the meeting. He added that hundreds of children had died from Covid, a rate he said “compares quite terribly” to pediatric deaths during a major flu outbreak in 2009 and 2010.

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The two vaccines being considered on Wednesday appear significantly less effective against symptomatic infection than the adult vaccines when they were introduced. The FDA credits Omicron with being much better at evading vaccine defenses against infection than the original version of the virus.

Given the decline in protection seen in adult recipients and the rapid evolution of the virus, regulators said children who receive vaccines from Pfizer and Moderna will most likely need a booster. This would mean that Pfizer’s vaccine, developed with German company BioNTech, could finish in four doses, while Moderna’s could be three.

Both Pfizer-BioNTech’s and Moderna’s vaccines elicited levels of virus-neutralizing or blocking antibodies in children comparable to those in adolescents and young adults aged 16 to 25. Pfizer’s vaccine has been licensed for children ages 5 to 15 since last year, and regulators have said so. helped prevent hospitalizations and deaths.

After two doses, Pfizer’s vaccine was only about 28% effective in preventing symptomatic infection in children aged 6 months to 4 years. Pfizer suggested the vaccine was 80% effective after a third dose, but the finding was based on just 10 cases out of a subset of the 1,678 trial participants. The trial protocol specified that assessments of vaccine effectiveness should be based on at least twice as many cases; On Wednesday, the small number of cases on which the conclusion on effectiveness was based was a cause for consternation among committee members and regulators.

Dr. Doran Fink, a federal vaccine regulator, called Pfizer’s efficacy data preliminary. “We consider it imprecise and potentially unstable,” he said. “The exact efficacy of the vaccine after the third dose requires additional data.”

Moderna found its vaccine to be 51% effective in preventing symptomatic infections in children 6 months to 2 years old and 37% effective in children 2 to 5 years old. These results appear consistent with those reported in adult studies in the Omicron era, the FDA said. Yet vaccination continues to provide strong protection against serious illnesses that lead to hospitalization and death.

A panelist asked on Wednesday if there was any evidence of how children who had recovered from the virus reacted to the vaccine – a common question among parents.

A Moderna official said the company’s study showed young children who received Omicron and were vaccinated had higher levels of protection, a conclusion supported by outside research.

Although Moderna’s efficacy data seems a little stronger than Pfizer’s, scientists have strongly cautioned against such comparisons.

“They are different populations. The studies were done at different times. Results are reported in different ways, with different endpoints,” said Dr. Jesse L. Goodman, former chief scientist at the FDA. “Scientifically, we don’t have a direct comparison.

Correction:

June 15, 2022

Due to an editing error, an earlier version of this article incorrectly indicated when the Pfizer-BioNTech vaccine was licensed for different age groups in the United States. The vaccine was licensed for ages 16 and older at the end of 2020, not in 2021, when vaccines were licensed for ages 5 to 15.

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