Letters to the Editor • Opinion
Is the pandemic under control? Yes. Over? No.
The Washington PostDemocracy Dies in Darkness

Pfizer covid shot 80 percent effective in younger kids, early data shows

Pfizer and German partner BioNTech said their three-dose coronavirus vaccine regimen was safe and generated a robust immune response in infants, toddlers and preschoolers. (Elaine Thompson/AP)

Pfizer and its German partner, BioNTech, said Monday that an early analysis showed their three-dose coronavirus vaccine regimen triggered a strong immune response in younger children, proving 80 percent effective at preventing symptomatic infections in children 6 months to 4 years old.

The results, along with other recent developments, signal that the long and frustrating wait for a vaccine for the youngest children, the last group to lack access, could be over within weeks.

The Food and Drug Administration, in an announcement a few hours after Pfizer and BioNTech issued a news release about their results, said the agency’s outside experts are scheduled to meet June 15 to discuss the Pfizer-BioNTech vaccine and another shot for the youngest children from the biotechnology company Moderna.

If the FDA advisory panel looks favorably on the pediatric vaccines, the agency could authorize the shots as soon as June 16 or 17. Vaccine advisers to the Centers for Disease Control and Prevention then would consider who should get the shots, with a final recommendation coming from the agency’s director, Rochelle Walensky, shortly afterward. The vaccines would be available almost immediately.

Pfizer and BioNTech said they plan to finish filing data, which has not been peer reviewed, with the FDA this week. The companies warned that the efficacy number was fluid because results are still arriving.

“This is incredibly exciting data!” Kawsar Talaat, a pediatrician and vaccine expert at Johns Hopkins Bloomberg School of Public Health, wrote in an email. “I also think that it reinforces what we’ve seen in adults as well. For the Omicron variant, a third dose is necessary for optimal protection.”

The FDA is already reviewing the pediatric vaccine from Moderna, a two-shot regimen that was 51 percent effective in preventing illness in children between 6 months and 2 years old, and 37 percent effective in children 2 to 5 years old.

Regulators previously had set aside three possible dates for the FDA’s outside experts to debate pediatric vaccines. The earliest, June 8, presumably was for Moderna, whose review is further along. Those meetings have been canceled. Now, the June 15 meeting sets up a head-to-head comparison of efficacy and safety for Moderna’s two-shot regimen and Pfizer-BioNTech’s three-shot vaccine for the youngest children.

“The overall data are encouraging such that it is really hard to look at one vaccine apart from the other,” according to an official familiar with the process who spoke on the condition of anonymity because that person was not authorized to speak publicly.

Some parents reacted angrily, saying the FDA should move ahead with the June 8 meeting to consider the Moderna vaccine. Fatima Khan, co-founder of Protect Their Future, a group of physicians and parents who have been pushing the FDA to accelerate pediatric vaccines, said: “It’s so disappointing. I think what is really frustrating here, from the very beginning, we have been saying, ‘Let’s follow the science. Let’s review ASAP and have the same urgency you have had with the adults’ vaccines.’ ”

In a statement, the group noted that Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said the agency would not delay the review of the Moderna vaccine to allow Pfizer-BioNTech to catch up.

But Marks also has said several times it might be preferable to review both vaccines at the same time with the FDA’s outside advisers. He has said he would consider doing that if it would not cause more than a week’s delay in authorizing the Moderna vaccine.

In a statement Monday, the FDA defended its plan. The agency said putting both vaccines before the committee “is the best approach to ensure the most informed recommendations from our external advisers and allow the most optimal decision-making by FDA experts because they will have the comprehensive analyses for both vaccines in the youngest patient populations before them.”

Kavita Patel, a primary care doctor at Mary’s Center, which has clinics in the District and Maryland, said she thinks a simultaneous review of the two vaccines “gives providers a lot of benefit.” That’s because, she said, “the most common question we will get from early vaccine recipients is which one is better. We will say, ‘This is what the data show.’ ”

If the FDA advisory committee reviewed the Moderna shot June 8 and the Pfizer-BioNTech vaccine two weeks later, “we would say we don’t know which is better,” Patel said. “I might say, ‘Wait two weeks’ ” until the panel reviews the Pfizer-BioNTech vaccine.

“The more confusing it is for doctors to explain, the less likely people are to get their children vaccinated,” Patel said.

Nimmi Rajagopal, a family medicine doctor at Cook County Health in Chicago and mother of a 3-year-old son, agreed. She said she believes there is “value to all the information coming out at once. It’s confusing enough already.”

Under the revised schedule, the FDA and its outside experts will discuss the Moderna vaccine for children and adolescents from 6 to 17 years old on June 14; the Pfizer-BioNTech vaccine already is authorized for that age group.

The following day, they will review vaccines for the youngest children, with advisers evaluating the Moderna vaccine for children 6 months through 5 years old and the Pfizer-BioNTech vaccine for children 6 months through 4 years old.

A CDC planning document notes that vaccines are expected to be shipped immediately after being authorized by the FDA. Preordering for doses could begin in late May or early June, but an exact date will be contingent on when the FDA’s external advisers meet.

So far, the Pfizer-BioNTech data is available only through a news release with few details and a top-line efficacy number that could change. The companies are seeking authorization for a regimen with a two-month gap between the second and third doses, but it is not yet clear how closely the study data reflect that. The average gap in the trial could have been longer for many participants who may have been first vaccinated last year — and a longer interval could account for some of the protection, because a longer time gap is thought to help with the immune memory response.

The Pfizer-BioNTech vaccine for children younger than 5 is a three-shot regimen tested in nearly 1,700 children. Each shot is one-tenth of the adult dose. The third shot was added in December after it became clear that two shots failed to muster an immune response equivalent to what was generated in young adults in early coronavirus vaccine trials.

Although that setback in the trial of two doses was hugely disappointing to parents, the addition of a third shot was seen by many experts as necessary because the omicron variant of the coronavirus had fundamentally changed the pandemic. The two shots that provided robust protection against infection and severe illness early in the health crisis were markedly less protective against the omicron variant.

“Omicron has really thrown a curveball on us — it seems that two doses are not sufficient for adequate efficacy against infection with Omicron, with any vaccine, at any age,” Flor Munoz, a pediatric infectious-disease specialist at Baylor College of Medicine, said in an email before the new data was released.

While the adult trials recruited tens of thousands of volunteers and waited to see if vaccinated people were better protected, the children’s vaccine trials were primarily designed to measure immune responses using blood tests.

The criteria for success was whether a vaccine provoked a comparable immune response to what was seen among young adults in trials conducted before the widespread emergence of variants. Both the three-shot Pfizer-BioNTech regimen and two doses of the Moderna pediatric vaccines succeeded on that measure, although the significance of that benchmark has shifted with the arrival of the omicron variant.

The companies also measured cases of symptomatic illness in the study population, and Pfizer and BioNTech said the 80 percent efficacy finding was preliminary and based on 10 cases of covid-19 in the study population as of the end of April. Once 21 cases have occurred, the companies will conduct a more formal analysis of efficacy.

David Benkeser, a biostatistician at Emory University’s Rollins School of Public Health, said that the updated data would probably be ready before a decision would need to be made and that he wouldn’t be surprised if the efficacy number declined somewhat as more cases occur.

“Even still, it appears the data are so far pointing towards a safe and effective vaccine for young children,” Benkeser wrote in an email.

If Pfizer’s efficacy data holds up, it could pose a conundrum for public health officials, physicians and parents. If both vaccines are cleared by the FDA, the CDC advisory committee could weigh whether one vaccine should be recommended over the other.

Moderna is studying a booster given six months after the second shot in the initial series.

In either case, the hope is that children will be fully vaccinated in advance of a potential surge in the fall.

Coronavirus: What you need to know

The latest: The CDC has loosened many of its recommendations for battling the coronavirus, a strategic shift that puts more of the onus on individuals, rather than on schools, businesses and other institutions, to limit viral spread.

Variants: BA.5 is the most recent omicron subvariant, and it’s quickly become the dominant strain in the U.S. Here’s what to know about it, and why vaccines may only offer limited protection.

Vaccines: Vaccines: The Centers for Disease Control and Prevention recommends that everyone age 12 and older get an updated coronavirus booster shot designed to target both the original virus and the omicron variant circulating now. You’re eligible for the shot if it has been at least two months since your initial vaccine or your last booster. An initial vaccine series for children under 5, meanwhile, became available this summer. Here’s what to know about how vaccine efficacy could be affected by your prior infections and booster history.

Guidance: CDC guidelines have been confusing — if you get covid, here’s how to tell when you’re no longer contagious. We’ve also created a guide to help you decide when to keep wearing face coverings.

Where do things stand? See the latest coronavirus numbers in the U.S. and across the world. The omicron variant is behind much of the recent spread.

For the latest news, sign up for our free newsletter.