Why the Covid-19 Vaccine Rollout Will Be Different for Kids

Pfizer expects to release the first data about vaccine efficacy and safety in adolescents by this summer

A child sits next to a woman with blond hair while a pediatrician looks at his face. All three are wearing masks.
Now that several Covid-19 vaccines have been shown safe and effective in adults, the producers can begin clinical trials in adolescents. Stock photo via Getty Images

Around the country, the Covid-19 vaccine rollout is expanding from healthcare workers and people who live in long-term care facilities to older adults, essential workers and people with chronic medical conditions, depending on location.

Two vaccines have been authorized so far—one created by Moderna is authorized for people ages 18 and older, and one by Pfizer that is authorized for people 16 and older. The Food and Drug Administration (FDA) has determined a third vaccine, created by Johnson & Johnson, is safe and effective at preventing severe Covid-19 in people 18 and older, and they will meet to review the vaccine for authorization on Friday.

But why is there an age limit for who can receive a vaccine right now, and when will a vaccine become available for kids and teenagers?

Vaccinating young people will be necessary to approach herd immunity and significantly slow the spread of Covid-19 in the United States, Sarah Zhang reports for the Atlantic. The FDA has specific regulations and protections in place for testing new medications in children, in order to reduce risk. That means that vaccine trials have to be conducted separately for adults and children.

Pfizer has enrolled about 2,300 volunteers between 12 and 15 years old in a vaccine trial, and they hope to have initial data by this summer, Sarah Elizabeth Richards reports for National Geographic. Moderna is still recruiting volunteers and expects to have data in 2022, ProPublica public health journalist Caroline Chen tells Hari Sreenivasan at PBS Newshour.

Why do kids need a Covid-19 vaccine?

On a community level, a kid who catches Covid-19 has the potential to spread that virus to the adults in their life who may not have gotten vaccinated yet. Some people can’t get vaccinated because of their immune systems or because they have a history of allergic reactions to vaccines, for example.

On an individual level, kids face the risk of severe symptoms that could make them miss school, and make their parents miss work. “Even those two-to-three-day illnesses can pile up,” says pediatrician Jeff Gerberof the Children’s Hospital of Philadelphia, to the Atlantic.

In rarer cases, some children have reported long-lasting symptoms after their initial course of Covid-19 in a way that resembles “long Covid” in adults. Other times, an inflammatory condition called MIS-C appears weeks or months after the infection, which can be treated with hospitalization.

About 250 children have died of Covid-19 in the United States out of over 500,000 deaths total. That makes it among the more serious diseases that a child could catch. To put it in perspective, Covid-19 is “causing more deaths than influenza does in a typical season,” and it’s recommended that children get an annual flu vaccine because of that risk, says pediatrician and bioethicist Douglas Diekema of Seattle Children’s Hospital to Science magazine’s Jennifer Couzin-Frankel. Diekema continues, “Those are unnecessary deaths and should be prevented.”

Why were the first vaccines just approved for adults?

Vaccine trials happen in order of “age de-escalation,” beginning with adults, who are the most at-risk of Covid-19 that’s severe enough to require hospitalization. After several phases of testing, culminating in a trial with tens of thousands of volunteers, the FDA reviews the companies’ data for the vaccines’ efficacy, and very importantly, their safety.

Only after proving that the vaccine is safe and effective in adults can the companies begin trials in children.

“Some people have wondered why kids weren’t enrolled in Covid-19 trials earlier, but the purpose of these regulations is to protect kids from unnecessary risk,” says St. Jude Children’s Research Hospital Ethics Committee chairperson Liza-Marie Johnson to National Geographic. “Research is opened to minors when a trial is low risk and offers potential for benefit.”

Some vaccine trials were halted or paused because an adult volunteer had an adverse side effect; regulations reduce the risk of that happening to a child during trials for younger age groups.

Continuing with the age de-escalation strategy, the next trials will test full-dose vaccines for safety and immune response in adolescents over 11 years old. After that, companies can move to children over six years old, and then to infants. Some scientists have advocated for testing half- and quarter-dose vaccines in younger children.

“If you get the same immune response at a quarter of the dose and it decreases side effects, well then we would probably give a smaller dose,” says Robert Frenck, who directs Cincinnati Children’s Hospital’s Gamble Vaccine Research Center and is involved in Pfizer’s adolescent trial, to Science magazine.

Over 20 million people have been fully vaccinated in the United States, with few lasting side effects, according to the FDA.

“They’re really looking at the data very, very closely,” says Mount Sinai Hospital pediatrician Kristin Oliver to the New York Times’ Apoorva Mandavilli. “As a pediatrician and a mom, I have really good confidence that those systems work.”

How are the trials different for adults and children?

The trials in adults waited for a small number of tens of thousands of participants to test positive for Covid-19, and showed that people with the vaccine were 20-times less likely to catch it than those who weren’t vaccinated. Now, the trials in adolescents and children will look for signs of immune system activity that can be detected in the blood, so no one has to get sick in order for the companies to gather data.

Megan Egbert’s two daughters are participating in the adolescent vaccine trial for Moderna, and she tells National Geographic that the trial requires that they keep a diary of symptoms for a week after each shot, attend telemedicine appointments regularly, and get four blood draws and four Covid-19 tests over the course of 13 months. They will also each be compensated $1,600. “I tell them this is like a job,” Egbert tells National Geographic.

It may take extra time to approve the vaccine for younger people in part because the vaccine for adults was actually fast-tracked into emergency use authorization, which requires just two months of safety data. The FDA is looking for six months of safety data for the vaccine in adolescents, per the Atlantic.

It can also be difficult to recruit volunteers for a study in younger people, especially if parents don’t feel like their children are under an immediate threat, reports the Atlantic. Praxis Communications’ senior vice president and managing director Tricia Barrett tells National Geographic that they focus on giving participants an emotional connection to the purpose of clinical trials.

“There’s a big sense of altruism. Parents think, 'I’m not only helping my child, but others as well,'” she says. “For the kids, we help make them feel like part of something cool.”

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