FDA Urges Pfizer-BioNTech and Moderna to Expand Trials for Kids 5 to 11

Child getting vaccinated.

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Key Takeaways

  • Pfizer-BioNTech and Moderna are expanding their clinical trials for children aged 5 to 11 at the urging of the FDA.
  • The goal of the expansion is to monitor for possible rare side effects like cases of myocarditis and pericarditis.
  • Doctors say, while this may delay the authorization of the vaccines, it's a great step for ensuring safety.

COVID-19 vaccine makers Pfizer-BioNTech and Moderna are expanding their clinical trials for children aged 5 to 11 at the urging of the Food and Drug Administration (FDA), according to a new report.

The goal of the expansion is to help detect the frequency of rare side effects in this age group, including myocarditis and pericarditis, health conditions that involve inflammation of different parts of the heart, according to The New York Times. Some people under the age of 30 have reported these health complications after receiving the COVID-19 vaccine.

The FDA has asked both companies to increase the size of their clinical trials to include 3,000 children between the ages of 5 and 11, which is double the original number of study participants.

Both vaccines have been linked to cases of myocarditis and pericarditis in more than 1,2000 people, according to data released by the Centers for Disease Control and Prevention (CDC) in June.  Of those, about 500 were younger than 30. While rare, myocarditis was most common in males aged 12 to 29 years after their second dose of the vaccine, with symptoms usually showing up within two weeks.

“This expansion is to make sure they aren’t seeing a much higher rate of heart inflammation in younger children,” Mark Hicar, MD, PhD, associate professor of infectious disease at the University at Buffalo in New York, tells Verywell.

Why Is It Necessary to Expand These Trials?

Experts say it’s all about safety and making sure parents and healthcare providers are aware of the risks and benefits of the vaccine.

“We want to make sure we’re aware of all of the possible side effects,” Danelle Fisher, MD, FAAP, pediatrician and chair of pediatrics at Providence Saint John’s Health Center in California, tells Verywell. “If there is an increase in the number of myocarditis and pericarditis cases, we want to make sure that we have an opportunity to detect them and do the appropriate care.”

“It is important to remember that millions upon millions of doses have vaccine have been safely given,” David J. Cennimo, MD, associate professor of medicine and pediatrics at Rutgers New Jersey Medical School, tells Verywell.

He also points out that most patients who develop myocarditis or pericarditis after having the vaccine “recover very well,” adding that “myocarditis is seen more frequently with COVID-19 infection than with vaccine.”

“All of that stipulated, this does seem to be a side effect of the vaccine,” Cennimo continues. “Since it is more common in adolescents, there is some concern that even younger children could have higher rates of myocarditis.”

Because this is still a very rare side effect, it needs a larger number of children in a clinical trial to be detected, Cennimo says. “I think the FDA is doing a diligent investigation to be able to say there is no significant increased risk,” he adds.

What This Means For You

If you have young children, you may need to wait a little longer to get them vaccinated against COVID-19 due to the FDA expanding clinical trials for children. But if your child is aged 12 or older, they are eligible to get vaccinated and you can find an appointment at

Will This Delay Authorization?

It seems like it will. Moderna started recruiting patients in March at 69 locations across the country, with an estimated study completion date of June 12, 2023, according to clinical trial data. That will likely be pushed back.

But Pfizer is on track to file a request for emergency use authorization of its vaccine in the five- to 11-year-old age group by the end of September, even after adding more children to the trial.

“Yes, this could delay results of the trial, but safety is always paramount,” Hicar says. “The vaccine trial process is a very well-regulated process with government, private entity, and independent reviewer input that puts safety at the forefront.”

Even after vaccines get emergency use or full approval, cases will continue to be reviewed to modify recommendations, he says.

Fisher acknowledges that the process can feel frustrating for parents. “With the Delta variant going around, we have to weigh the pros and cons of delaying authorization,” she says. “We want to make sure this vaccine is safe, but we also want to protect our children.”

Overall, experts say they feel confident that the vaccines will be safe for younger children. The delay “should be seen as a concrete demonstration of the robust safety measures in the vaccine approval process,” Cennimo says.

“I personally am anxiously awaiting vaccines for my children who are in the younger age group and have the utmost confidence in this process,” Hicar adds.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. COVID-19 mRNA Vaccines in Adolescents and Young Adults: Benefit-Risk Discussion. June 23, 2021.

By Korin Miller
Korin Miller is a health and lifestyle journalist who has been published in The Washington Post, Prevention, SELF, Women's Health, The Bump, and Yahoo, among other outlets.