The findings could add momentum for F.D.A. authorization of the pediatric dose, perhaps next week, a long-awaited development that would affect 28 million children.
Oct. 22, 2021, 7:39 p.m. ET
WASHINGTON — Pfizer reported long-awaited data on Friday showing that its coronavirus vaccine had a 90.7 percent efficacy rate in preventing symptomatic Covid-19 in a clinical trial of 5- to 11-year-olds, a finding that may lead to the first authorization of a vaccine to protect young children from the virus.
The company and its partner BioNTech submitted the information to the Food and Drug Administration, which was expected to release its own analysis of the data on Friday night. The findings could add momentum for F.D.A. authorization of the pediatric dose on an emergency basis, perhaps as early as next week, opening a new phase of the nation’s vaccination campaign.
The agency’s independent committee of vaccine experts is set to vote Tuesday on whether to recommend authorization. If the F.D.A. rules in favor and the Centers for Disease Control and Prevention and its own panel of vaccine experts agree, the 28 million children in that age group could become eligible for shots in the first week of November.
The Biden administration has been eagerly promoting the prospect, and many parents are anxiously awaiting the development. Covid-19 cases among those younger than 18 peaked in the first week of September, when nearly a quarter of a million cases were reported.
But they remain high, with more than 130,000 cases reported in the second week of October, the American Academy of Pediatrics said, accounting for a quarter of all cases nationwide. Fewer than two percent of those cases resulted in hospitalization, but that figure was based on data from only half the states, the organization said.
Pfizer and BioNTech announced a month ago that their vaccine worked well for young children, but no comprehensive clinical data was released publicly until Friday. Children in the trial received two doses of 10 micrograms — one-third of the adult dose — three weeks apart. Researchers said that the dosage was safe, and that trial participants had seen only mild side effects.
Of 2,268 children in the trial, twice as many were given the vaccine as received a placebo. Sixteen children who received the placebo got Covid-19, compared with three who received the vaccine. All of the Covid cases occurred in July or later, as the highly transmissible Delta variant was spreading in the United States and globally, according to the company.
Pfizer said it had follow-up safety data for an additional 2,250 children, but only for a median of two-and-a-half weeks after they received a second dose.
There were no cases in the trial of severe Covid, or of two rare heart conditions that have been linked to the vaccine in teenagers and adults, especially young males. But it was likely not big enough to detect whether those particular conditions — myocarditis and pericarditis — might appear with any frequency in younger children.
Researchers looked at immune responses, comparing them with levels in adults who had received the vaccine. Pfizer then deduced that the protection afforded by the lower dose in children could be as substantial as that afforded by the higher dose in adults. That approach is particularly important in small trials.
After the second shot, the children had levels of neutralizing antibodies that were at least equal to those of 16-to-25-year-old volunteers in another Pfizer-BioNTech trial. Although antibody levels are just one measure of the immune system’s response, experts have said such a finding would indicate that one-third of an adult dose was the proper dosage for young children.
Regulators and experts have linked the conditions of myocarditis, or inflammation of the heart muscle, and pericarditis, or inflammation of the lining of the heart, to both the Pfizer-BioNTech and Moderna vaccines, which are based on similar technology. For men under 20 who receive two full doses of one of those vaccines, the rate of myocarditis may exceed 100 cases per million doses, according to data presented at a C.D.C. meeting on Thursday.
Studies have shown that the risk of developing those heart problems from Covid-19 is higher than from vaccination. Still, some countries have recommended a single dose of the Pfizer-BioNTech vaccine for children 12 and older, offering less protection but possibly with a lower risk of side effects.
Experts will almost certainly raise concerns about those side effects at the F.D.A. advisory committee meeting, according to Dr. H. Cody Meissner, a member of the panel and the chief of the Division of Pediatric Infectious Diseases at Tufts Children’s Hospital in Boston.
What to Know About Covid-19 Booster Shots
The F.D.A. has authorized booster shots for millions of recipients of the Pfizer-BioNTech, Moderna and Johnson & Johnson vaccines. Pfizer and Moderna recipients who are eligible for a booster include people 65 and older, and younger adults at high risk of severe Covid-19 because of medical conditions or where they work. Eligible Pfizer and Moderna recipients can get a booster at least six months after their second dose. All Johnson & Johnson recipients will be eligible for a second shot at least two months after the first.
Yes. The F.D.A. has updated its authorizations to allow medical providers to boost people with a different vaccine than the one they initially received, a strategy known as “mix and match.” Whether you received Moderna, Johnson & Johnson or Pfizer-BioNTech, you may receive a booster of any other vaccine. Regulators have not recommended any one vaccine over another as a booster. They have also remained silent on whether it is preferable to stick with the same vaccine when possible.
The C.D.C. has said the conditions that qualify a person for a booster shot include: hypertension and heart disease; diabetes or obesity; cancer or blood disorders; weakened immune system; chronic lung, kidney or liver disease; dementia and certain disabilities. Pregnant women and current and former smokers are also eligible.
The F.D.A. authorized boosters for workers whose jobs put them at high risk of exposure to potentially infectious people. The C.D.C. says that group includes: emergency medical workers; education workers; food and agriculture workers; manufacturing workers; corrections workers; U.S. Postal Service workers; public transit workers; grocery store workers.
Yes. The C.D.C. says the Covid vaccine may be administered without regard to the timing of other vaccines, and many pharmacy sites are allowing people to schedule a flu shot at the same time as a booster dose.
“I certainly hope that we’re in a position to to recommend this because people are certainly waiting for it, they’re anxious to have it,” he said. “But our responsibility is to balance both risk and benefit.”
Vaccine experts have said that Pfizer’s lower dosing could mitigate risks.
Dr. Brian Feingold, an expert on heart inflammation in children at the UPMC Children’s Hospital of Pittsburgh, said that even though Pfizer’s trial was small, the overall results were still worth taking seriously.
“If you just focus on myocarditis or other potentially rare things, you’re probably still going to be left wanting more information,” he said. “But if you focus on the safety of the vaccine in total, and the efficacy, you can learn a lot.”
“We cannot consider a risk in isolation,” he added. “Risks from Covid need to be considered when you make a decision about whether this vaccine has greater net benefit.”
The Centers for Disease Control and Prevention, which sets vaccine policy for the government, has scheduled a meeting of its advisory committee for Nov. 2 and 3 to consider the issue. Federal officials have said they intend to ship 15 million doses to the states immediately if regulatory and health officials authorize the move. The needles that administer the vaccine and the vials that hold it will need to be smaller for children who are still largely in elementary school.
About 17 million adolescents aged 12 to 15 became eligible for the Pfizer-BioNTech vaccine in May. Vaccine manufacturers continue to study the possibility of a vaccine for those aged six months to 5 years old.
Only about one in three parents of 5- to 11-year-olds planned to get their children inoculated “right away” once a vaccine is authorized, according to polling by the Kaiser Family Foundation conducted last month. Another third said they wanted to “wait and see” how the vaccine affected children.
But that same polling showed that reluctance among parents of teenagers had dropped in the months since vaccines became available to that age group.
Aina J. Khan contributed reporting from London.