The Washington PostDemocracy Dies in Darkness

Moderna seeks authorization of coronavirus vaccine for youngest children

Ilana Diener holds her 3-year-old son, Hudson, during an appointment for a Moderna vaccine trial in Commack, N.Y., in November. (Emma H. Tobin/AP)
8 min

Vaccine maker Moderna requested emergency use authorization Thursday of its coronavirus vaccine for babies, toddlers and young children — a highly anticipated step toward making shots available to the last group in U.S. society lacking access.

The path to a vaccine for the youngest children has been tortuous, marked by disappointing results, delays and confusing communication — and in the meantime, as many as 75 percent of children have been infected with the virus since the dawn of the pandemic, according to a new study.

Moderna’s announcement will intensify pressure on the Food and Drug Administration to move quickly, as parents, pediatricians and politicians have become increasingly impatient about the lack of vaccines and treatments to protect young children.

Politico reported last week that the agency may not make a decision on the vaccine until June and was leaning toward reviewing the Moderna shot for children younger than 6 alongside a three-dose regimen from Pfizer and German partner BioNTech. That has stoked anger and suspicion among some parents, who maintain that the agency is delaying vaccines.

Children ages 5 to 11 became eligible for the two-dose coronavirus vaccine from Pfizer on Nov. 2, 2021. (Video: Luis Velarde/The Washington Post, Photo: Cincinnati Children’s/The Washington Post)

The full data supporting the application is expected to be filed by early in the second week of May, according to a senior Biden administration official, who spoke on the condition of anonymity because they were not authorized to discuss the matter publicly.

FDA spokeswoman Stephanie Caccomo said the agency would not be able to reach a decision without a complete filing and said it was not possible to predict how long a review of the data would take. The agency “will review any [emergency use authorization] request it receives as quickly as possible using a science-based approach,” she wrote in an email.

Moderna’s chief medical officer, Paul Burton, said in an interview that “it’s difficult to put an exact timeline, but I believe they recognize there is an unmet need here. I think they’ll try and move quickly.”

The findings on the Moderna pediatric vaccine are not the slam dunk the public has grown accustomed to when results have been released on coronavirus vaccine studies. That largely reflects the emergence of the omicron variant.

Trials of vaccines for young children have been designed to show whether, in laboratory tests, the shots generate an army of disease-fighting antibodies equivalent to or better than the response that protected young adults earlier in the pandemic. Moderna’s study showed that its two-shot vaccine regimen — each shot is a quarter of the dose given to adults — was successful in mustering an immune response in children younger than 6 similar to what had been found in the blood of young adults.

But there’s a difference between showing success in a lab test and protecting people in the outside world, especially as the omicron variant rampaged.

Amid the omicron surge, two shots were only modestly effective in preventing illness caused by that variant, mirroring the performance of the vaccine in adults. Moderna’s updated analysis showed it 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. Doctors expect that protection against severe illness would be stronger, but because hospitalization and death are rare outcomes in children, there were no cases in the trial, and no conclusion could be drawn about the protection the vaccine provides against severe illness.

Moderna said the vaccine proved safe and well-tolerated in its trial, which included 6,700 children under the age of 6. Fevers occurred in about 15 percent of 2-to-5-year-olds in the trial and 17 percent of the children between 6 months and 2 years old.

Next, the FDA will scrutinize that data.

The presence of the omicron variant is likely to frame the debate about the vaccine, making it harder for experts to agree about what constitutes a successful shot, particularly in young children, who rarely suffer severe illness after infection. The benchmark for success has in many ways become outdated because the level of antibodies that protected against the original coronavirus strain no longer offers substantial protection.

“This has not been an easy task,” said Kathryn M. Edwards, a professor of pediatrics at Vanderbilt University Medical Center. “We were all just saying ‘hallelujah’ when it looked like the vaccine was 95 percent efficacious. But we have variants, and the vaccine is not that effective for them, and waning is a real problem. And waning is happening with covid faster than we have with other vaccines. It’s not an easy problem.”

Many experts agree that the omicron variant has made it clear a booster dose will be needed, including in young children. The third dose improves and broadens the immune response against variants. But some argue that a two-shot course should be authorized, even if a three-shot regimen from Pfizer-BioNTech may be authorized close behind.

“The sooner the better in my mind. It doesn’t matter if it’s Moderna or Pfizer or both,” said Sunanda Gaur, a professor of pediatrics at Rutgers Robert Wood Johnson Medical School. “Let’s get these kids vaccinated. Let’s get started, and if they need a booster, they’ll get a booster later on.”

The finding that most children have already been infected may also become part of the discussion. Many physicians favor the additional protection afforded by vaccination because it is not known how long immunity from an infection lasts, and it is clear that reinfection can occur. Still, it’s not likely to be a settled matter because most children are at low risk of severe illness, raising questions among some parents — and even specialists — about how vaccines should be used, given the vast resources needed to vaccinate all children.

“Does a universal campaign to vaccinate all kids, does it still make sense?” asked Richard Malley, an infectious-disease doctor at Boston Children’s Hospital, while emphasizing the importance of vaccinating children at risk of complications from infection. “The U.K. came down and said the vaccines are available, but it is not going to make a strong push. The conversation has to happen here.”

Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said at a Senate committee hearing Tuesday that the agency will “move quickly without sacrificing standards to finish our evaluation of covid-19 vaccines for children under 5 years of age. It’s one of our highest priorities.”

But, he added, “we can’t actually finish our reviews until we have complete applications.”

Burton said the filing this week “should provide all the core, fundamental data the FDA needs. … This should be sufficient for FDA to begin their review.”

It is unclear whether the agency will review Moderna’s entire data submission at once, which includes findings on children up to age 17. Children as young as five already have access to the Pfizer-BioNTech vaccine. Moderna’s pediatric vaccine program has been stalled for almost a year because of concerns about rare cases of heart inflammation in adolescents. Some parents have called for the agency to prioritize young children because they don’t have access to any protection.

Some 5-to-11-year-olds received the nation's first children's coronavirus vaccine on Nov. 3, 2021, after the CDC authorized immunizing millions of kids. (Video: Justin Scuiletti/The Washington Post)

But the FDA has had a head start on reviewing some of the data on older age groups, so it is unclear whether reviewing the entire package at once would be slower. Last year, Moderna submitted its authorization for adolescents between the ages of 12 and 18 and sought authorization of a shot for children 6 to 11 a few weeks ago, Burton said.

The picture could grow more complicated in coming weeks because results for the Pfizer-BioNTech pediatric vaccine may be reported even as the FDA scrutinizes Moderna’s data.

The Pfizer-BioNTech vaccine had initially been expected to roll out early this year. But in December, the company announced that its two-shot regimen, which is a lower dose than Moderna’s, had failed to meet the laboratory benchmark of achieving an immune response comparable to what had been reported in young adults. The company added a third dose, and executives have predicted their three-shot regimen could become available in June.

Some parents and pediatricians are putting pressure on the agency to move quickly, but Vanderbilt’s Edwards cautioned that no steps should be skipped.

“We want to make sure the vaccine is safe,” she said. “One mistake with one vaccine because we are not meticulous and don’t use our usual careful methods will undermine everything.”

Lenny Bernstein and Frances Stead Sellers contributed to this report.

Coronavirus: What you need to know

End of the public health emergency: The Biden administration ended the public health emergency for the coronavirus pandemic on May 11, just days after WHO said it would no longer classify the coronavirus pandemic as a public health emergency. Here’s what the end of the covid public health emergency means for you.

Tracking covid cases, deaths: Covid-19 was the fourth leading cause of death in the United States last year with covid deaths dropping 47 percent between 2021 and 2022. See the latest covid numbers in the U.S. and across the world.

The latest on coronavirus boosters: The FDA cleared the way for people who are at least 65 or immune-compromised to receive a second updated booster shot for the coronavirus. Here’s who should get the second covid booster and when.

New covid variant: A new coronavirus subvariant, XBB. 1.16, has been designated as a “variant under monitoring” by the World Health Organization. The latest omicron offshoot is particularly prevalent in India. Here’s what you need to know about Arcturus.

Would we shut down again? What will the United States do the next time a deadly virus comes knocking on the door?

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