Earlier this summer, when it finally felt as if the pandemic had begun to recede in our city, we had to rush our toddler to the emergency room at 1 a.m. for sudden breathing troubles. We assumed it must have been a common respiratory infection, and a week later, his symptoms subsided. At the ER, our kid wasn’t tested for COVID. It didn’t even occur to us he could have been positive.
But then, I began hearing from friends whose 10-year-olds, 7-year-olds and even a 1-year-old had tested positive. Though we’ll probably never know for sure, I began to wonder if my son had actually contracted a mild case of COVID. Something felt out of sync. While everyone else was celebrating being vaccinated, kids were getting sick.
Now, it’s clear that the delta variant has turbocharged COVID case counts in many areas of the U.S. just as children are about to crowd into schools. One of the few silver linings of this pandemic is that children have been mercifully spared the worst COVID has to offer. But now, the proportion of COVID cases in children is increasing dramatically. During the last week of July, the number of infected children doubled compared with the previous week, with pediatric cases now making up about a fifth of total reported COVID cases. Hospitalizations among kids are at the highest at any point in the pandemic, and hospitals in multiple states are saying they’re seeing sicker kids (though whether these anecdotal reports prove Delta is more dangerous to kids is far from clear). “In pediatrics, we were in a comfort zone before, but now things are changing,” said Avinash Shetty, a pediatric infectious disease specialist at Wake Forest School of Medicine.*
Now, my toddler will be trundling off to preschool this fall, and I’ve begun to wonder: Why can’t young kids get vaccinated by now?
It once looked like they’d be able to. When Pfizer/BioNTech and Moderna launched their vaccine clinical trials for kids under 12 in March, parents, teachers, and pediatricians hoped they’d be nearing emergency use authorization for COVID vaccines for children under 12 years old close to the start of this upcoming school year. However, the Food and Drug Administration recently requested that the pharmaceutical companies double the size of their clinical studies. For the youngest kids, they may also need to collect safety data for six months, rather than the customary two months for emergency authorization in adults. Although a Pfizer spokesperson said in an email that the company hadn’t yet pushed back its timeline, many believe these requirements are likely to delay authorization until later this fall for ages 5–11, and possibly until 2022 for toddlers and babies.
The FDA’s justification is that it needs to determine whether a rare heart inflammation seen in teens and young adults after vaccination also occurs in younger children. But it’s not clear that the FDA’s new data demands will actually help answer this question; instead, the delay may needlessly withhold a vaccine from millions of kids just as their exposure to COVID skyrockets.
The data so far suggests that COVID risks to children under 12 are small, though greater for the more vulnerable and marginalized children in our society. A study published in June revealed that about half of infected kids never have any symptoms, and those who do only suffer mild ones (think fever, headache, or cough lasting about one week). According to the American Academy of Pediatrics, nationally 1 in 100 infected children are hospitalized and fewer than 1 in 10,000 die. Disease can take a toll without being fatal, and kids too can get long COVID, where symptoms linger for weeks or months. In a small proportion of kids—only about 4,400 or 0.1 percent of cases nationwide to date—a rare but scary complication called MIS-C can arise a few weeks after infection, which can inflame organs and tissues throughout the body. These numbers will likely be higher for kids with preexisting conditions and lower for healthy children. They are also higher for Black and Latino children. So far, 354 kids in the U.S. have died, and although even a single child lost to COVID is heartbreaking, the risk is on the same order of magnitude as the risk of dying from drowning or poisoning—that’s to say, well within the bounds of risks parents accept every day.
Most of this data is, of course, pre-delta. But Kawsar R. Talaat, a physician and co-director of clinical research at the Johns Hopkins Institute for Vaccine Safety, said, “I don’t know yet if we know if delta is more serious. But we do know the delta variant is generally more contagious, so it’s easier to spread it from person to person.” That means you’d expect that increased community transmission would lead to increased transmission among unvaccinated children, which would lead to a higher number of serious cases. Data from the U.K., where delta has been circulating for longer than in the U.S., is reassuring. The U.K. surge has subsided, and although more kids were infected, experts I spoke to emphasized there’s no compelling evidence so far from the U.K. that delta infections are more severe in kids. Even if you spent the pandemic not super worried about the effects of COVID on your child, you may be reasonably eager for them to be protected against the odds that they’d catch (and spread) this new strain. In a vaccinated child, any COVID risks will be much, much lower and the more serious effects may disappear altogether.
The concern for some parents—and the possibility that the FDA is guarding against, by asking for more data—is that vaccines may come with their own special risks to kids. It’s true that the immune systems of children differ in important ways from those of adults. As any parent can tell you, the common cold might cause a kid to be laid up for a week—while the adults in the household only get the sniffles. Because the young immune system has never encountered the pathogen before, it launches a full-fledged response. But when it comes to an entirely new pathogen—like the novel coronavirus—kids might have an advantage, as Donna Farber, an immunologist at Columbia University, explained to me. Encountering new pathogens is exactly what a child’s immune system is designed to do.
Whether the dexterousness of pediatric immunity explains why kids so often evade COVID’s effects isn’t settled science. But in instances when COVID does take a toll on kids, Farber told me, it’s possible that it’s a product not just of the virus itself but also an intensely active immune system that shifts recklessly into overdrive. Even for adults, many of the symptoms we associate with pathogens—fevers, inflammation, runny noses—aren’t due to the pathogens themselves but to our body’s defenses. The very-rare-but-scary bodywide inflammation during MIS-C, for example, which only appears weeks after infection in some kids, could be an uncontrolled immune response to a pathogen that no longer poses a threat.
Given children’s hyperactive immune systems, it’s possible that a vaccine—which also triggers the immune system using a harmless molecular mimic—could provoke the same damaging over-responses as the actual virus in some small-but-worrisome portion of children. Myocarditis—or inflammation of the heart muscle—may be another unhappy accident of young people’s powerful immune systems. It would explain why the side effect has been observed more frequently in teens and young adults. “Frequent” is a relative term, however. Post-vaccine myocarditis is extremely rare: There are only 323 confirmed cases out of 52 million shots administered to teens and young adults, and it hasn’t caused a single death. Myocarditis is generally more common in young males, and males aged 12 to 17 only had about a 1 in 15,000 chance of developing the condition after a jab—about the same odds as being struck by lightning. If you are worried about myocarditis, the best thing to do is get vaccinated: COVID infections cause far more cases than COVID vaccinations do. In young males, myocarditis is about six times more common following a COVID infection than following a vaccine, according to a preprint study posted in July.
So, while the myocarditis risk posed by the vaccine is one worth taking even for adolescents, it is absolutely worth asking whether the risk might be higher for younger kids. The FDA is right to want to sufficiently explore the question. But what’s odd about the FDA’s request for a safety follow-up period of six months is that myocarditis would typically show up within four weeks. When asked about the changes to study design in an email, an FDA spokesperson said it “cannot comment on or confirm the existence of any clinical trials or its interactions with manufacturers about their investigational products.” However, in an address to stakeholders from early July, Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said the pediatric studies will “take a little longer to do because we are requiring longer follow-up to make sure that the safety is adequate.”
It doesn’t seem like that’s necessary, since the main side effect to worry about would show up within weeks, not months. And it’s highly unlikely that the vaccine would produce entirely new side effects in kids. Donna Farber, the Columbia immunologist, said, “There’s just not evidence out there based on the vaccines we give to everybody that children are going to have bizarre adverse events that you don’t see in adults.” The American Academy of Pediatricians agrees. In a letter from early August, the organization of 67,000 physicians urged the FDA to authorize the vaccines for all children, citing “no biological plausibility for serious adverse immunological or inflammatory events to occur more than two months after COVID-19 vaccine administration.” By now, according to the AAP, the studies have already collected two months of post-vaccine data for the original group of 5- to 11-year-olds. Any unusual side effects would have almost certainly shown up by now, so requesting additional time would be pointless.
As for myocarditis, there is one thing that might get the FDA some genuinely useful information: making the studies larger. The organization’s request to double the study size makes sense, in principle—the more people in a study, the more likely you’ll detect rare side effects. But the rarer the side effect, the larger the study must be. Given that myocarditis is extremely rare, you’d have to increase the study size dramatically. For this reason, Talaat, the Johns Hopkins vaccine researcher, who’s also a site investigator for the Pfizer pediatric study, doesn’t think the FDA’s relatively modest expansion makes much sense. “Doubling the size of a study from 4,000 to 8,000 isn’t going to capture events like myocarditis,” she explained. “To capture super-rare events like that, what you’d really need is to deploy a vaccine,” she said.
As uncomfortable as it may be to feel like unwitting test subjects in some giant experiment, this is the only way any medical treatment can reach the market. It’s simply not possible to have a clinical study enrolling tens of millions of people, which would be required to detect super-rare events. Instead, the FDA carefully monitors adverse reactions as the vaccines are being widely administered. “We are watching these vaccines incredibly carefully. I don’t think there’s any vaccine in the history of time that has been as studied or under scrutiny to the extent that the COVID-19 vaccines are,” said Talaat. In other words, post-market surveillance is the best option; the new study size requirements, she said, “will just slow things down.”
With the delta variant, more time means more sick kids, increasingly making the FDA’s caution more harmful than good. And many parents are already eager to have their children vaccinated. Shetty, the Wake Forest pediatrician, said in his practice, “As the delta variant surges, more parents are asking about the vaccine for kids under 12.” “We cannot leave children behind, and not just to protect them,” he said, noting that unvaccinated kids may increasingly contribute to community spread of the virus. “Vaccinating children is a strategy to get us out of the pandemic.”
The precautionary principle states that we should err on the side of caution in the face of uncertain data. In the end, the FDA’s dilemma of whether to authorize the vaccine is a case of pitting two precautionary principles against each other. In terms of the delta variant, you could say, “Let’s vaccinate kids, just in case delta is more dangerous or kids worsen community spread.” Or, you could say, “Let’s not vaccinate kids, just in case the vaccines have unexpected dangerous side effects.” But not all data is equally uncertain. It’s almost certain that delta’s contagiousness will mean more kids getting seriously sick and more kids spreading the virus to others. It’s wildly unlikely that the vaccines will cause unexpected, terrible harms to children. If the FDA were to drop its requests for more data and grant emergency authorization to the vaccine today, I wouldn’t hesitate to make an appointment for my kid to get a shot.
Correction, Aug. 23, 2021: This article originally misidentified Avinash Shetty’s affiliation as Wake Forest University. It is Wake Forest School of Medicine.