vaccine syringes and vials
Photo: Phngs' Theph Cit Hay/Getty Images

In early May, the Food and Drug Administration authorized the use of the Pfizer-BioNTech coronavirus vaccine in children ages 12 to 15. And on June 10, Moderna requested FDA authorization for use of its vaccine in people ages 12 to 17, after reporting that clinical trials showed it was effective in adolescents. That means a second vaccine could be authorized for adolescents in the coming weeks.

“Having a vaccine authorized for a younger population is a critical step in continuing to lessen the immense public health burden caused by the COVID-19 pandemic,” said Peter Marks, M.D., director of the FDA’s Center for Biologics Evaluation and Research. “The FDA can assure the public and medical community that the available data meet our rigorous standards to support the emergency use of [the Pfizer] vaccine in the adolescent population 12 years of age and older.”

Since the U.S. started vaccinating 12 to 15 year olds, the vaccines have been shown to be powerfully protective in the real world, just as they appeared to be in clinical trials, says Tina Tan, M.D., a pediatric infectious disease specialist and professor of pediatrics at Northwestern University.

"They generate a very robust immune response," she says. She and other experts say the data supports vaccinating anyone who can be vaccinated to help stop the spread of COVID-19, especially as more transmissible variants continue to spread in unvaccinated populations.

More on COVID-19

Getting children vaccinated is essential for controlling the COVID-19 pandemic, says Gregory Poland, M.D., director of the Vaccine Research Group at the Mayo Clinic, who studies vaccine response in adults and children. “If you want your child to go to school, if you want them to be safe, to have the normal social experiences that are important to childhood, please protect them by getting them vaccinated,” he says.

To better understand what we know about COVID-19 vaccines for children, CR consulted with experts and reviewed the available data. Here are answers to some common questions parents may have. 

Do Kids Really Need to Get Vaccinated Against COVID-19?

Yes, they should.

In the early months of the pandemic, scientists learned that children and teens were less likely to get severely ill with COVID-19, though some still became very sick. So far, children make up about 13 percent of COVID-19 cases overall in the U.S., with adolescents more likely to develop severe disease like adults, says Kathryn Edwards, M.D., scientific director of the Vanderbilt Vaccine Research Program and a professor of pediatrics.

But they account for almost a quarter of new cases, and some states, including Colorado and Michigan, have seen a rapid spread of coronavirus infections among children.

Some of that is because as adults get vaccinated, they’re less likely to get infected, making children a greater proportion of overall cases. But another reason, Poland says, is that variants of the virus now circulating—such as the B.1.1.7 variant, currently the most prevalent in the U.S.—are more infectious. And that makes vaccinating children, who have always faced some risk from the virus, even more urgent.

“The estimate is there have been around 300 to 600 pediatric COVID deaths,” Poland says. “That’s likely to increase if we don’t stop transmission by getting as many people immunized as possible.”

So far, over 4 million children have been infected with the virus that causes COVID-19, leading to nearly 18,000 hospitalizations, Tan says. Many of these kids—including many who were never hospitalized—deal with lingering symptoms that can persist long after infection, she says.

Vaccination also helps prevent other serious outcomes in children, Edwards says. In rare cases, children who have had COVID-19 have developed a condition known as MIS-C, which can cause organ damage and even death. Scientists are also following children who have gotten COVID-19 to see whether any have lingering problems, especially cardiac issues. 

Are the Vaccines Effective in Kids?

So far, efficacy data on the Pfizer-BioNTech vaccine in children looks “stellar,” Poland says.

According to Pfizer and BioNTech, a clinical trial of that vaccine of 2,260 12- to 15-year-olds found it 100 percent effective at preventing COVID-19. Children in that age group had even higher levels of antibodies in response to the vaccine than 16- to 25-year-olds.

In May, Moderna announced that its clinical trial of 3,732 people age 12 to 17 showed that adolescent immune systems responded to its vaccine at least as well as the immune systems of adults over 18. The company also reported that its vaccine, which uses similar technology to the Pfizer-BioNTech vaccine, was not only 100 percent effective two weeks after the second dose but was also 93 percent effective two weeks after the first dose. 

It’s likely that in the real world these vaccines may be somewhat less than 100 percent effective but still very protective, Poland says. 

Information on the effectiveness of vaccines made by Johnson & Johnson and Novavax in children should be available soon, he says. 

Do Kids Get the Same Shot as Adults?

Yes, at least for now. In Pfizer-BioNTech’s clinical trial, 12- to 15-year-olds received the same vaccine and dosages as adults, on the same schedule, with a second dose three weeks after the first. In Moderna's trial, 12- to 17-year-olds also received the same doses as adults.

For the future, though, vaccine manufacturers are testing lower dosages of the Pfizer vaccine and others for younger children to see whether that provides the same immune system response as higher dosages, Edwards says. 

Are the Vaccines Safe for Kids?

Common side effects reported in children so far are similar to those in adults: injection site pain, fatigue, headaches, muscle aches, chills, joint pain, and fever. And as in other age groups, these were “well tolerated” in 12- to 15-year-olds, Pfizer and BioNTech say.

The same sorts of symptoms were seen in 12- to 17-year-olds who received the Moderna vaccine, according to the company, with headaches, fatigue, achiness, and chills reported.

“The reaction profiles were pretty comparable to what we see in adults,” Edwards says.

In mid-May, the CDC announced that they were investigating rare reports of heart inflammation—myocarditis and pericarditis—that have occurred after coronavirus vaccination, and the agency released additional data in June.

These cases have occurred mostly in male patients, have been more common after the second dose than the first, and there have been more reports of suspected myocarditis in people ages 16 to 24 after vaccination than would be expected normally for that population, according to CDC data. So far, there's little data on whether 12- to 15-year-olds, who just started getting vaccinated in May, are experiencing higher than expected rates of myocarditis. 

But while it's important that CDC is transparent about these investigations, parents should understand that these events are still extremely rare, says David Parra, M.D., a pediatric cardiologist and associate professor of pediatrics at Vanderbilt University. In 16- to 39-year-old people, there have been about 16 cases per million second doses administered, according to CDC data. And the majority of these suspected cases have been mild, with people recovering quickly. In 81 percent of cases with a known outcome, the patient has fully recovered.

These numbers are still small enough that we don't yet know exactly how much of a direct relationship there might be between vaccination and heart inflammation, says Parra—but we do know that COVID-19 can cause inflammation in the heart and other organs, he says. "Vaccination is really important, and from what we know, the risks of COVID are much higher than the risks of vaccination," he says.

Poland says that experts will be watching closely to ensure that side effects aren’t a bigger problem for younger children. He adds that one reason to test lower dosages is to try to minimize side effects for the youngest children.

But people shouldn’t let fear of short-term side effects be a reason to avoid getting a vaccine that can prevent a disease from causing long-term damage or death, he says. 

When Will Younger Children Be Eligible?

That’s not certain, but perhaps as early as next fall. That’s according to a May 4, 2021, Pfizer earnings call, in which the company described plans to seek FDA authorization for use of its vaccine in children ages 2 to 11 in September. Pfizer also said it hoped to get authorization for the vaccine for infants in November.

It's possible that this timeline could be pushed back by a couple months, Tan says, if the CDC and the FDA decide they want to see more safety data on younger populations.

Edwards says exactly when younger children will be eligible depends on how the trials go. “We’re all working really hard to make sure the vaccines are safe and effective” she says. “We will not go too fast. We will go in a careful, cautious manner.” 

Will Schools Require Kids to Be Vaccinated Against COVID-19?

More than 100 colleges and universities in the U.S. have said they’ll require students to be vaccinated against COVID-19 if they want to return to school in the fall.

Schools that serve younger children already often require proof of various immunizations before children enroll, but it’s not yet clear whether a COVID-19 vaccine will become one of them. Right now, those vaccines have an emergency use authorization from the FDA. Until vaccines receive full approval, Poland says he thinks schools probably won’t require kids to have one. But after the FDA does fully approve the vaccines for children, many schools are likely to require proof of vaccination, he says.

Edwards says she hopes that people are persuaded to get children vaccinated based on the “incredible success” we’ve seen the vaccines have at preventing disease so far. 

Editor’s Note: This article has been updated to include information on CDC investigations into reported myocarditis cases, after the FDA authorized the Pfizer-BioNTech vaccine for use in 12- to 15-year-old children, and to include results of a Moderna trial in adolescents. It was originally published May 4, 2021.