Is Heart Inflammation a Hurdle to Vaccinating Kids?

The most dependable method to irritate the heart is to trouble it with an infection. Lots of kinds of infections can handle it—coxsackieviruses, influenza infections, herpesviruses, adenoviruses, even the brand-new coronavirus, SARS-CoV-2. A few of these pathogens bust their method directly into heart tissue, harmful cells straight; others rile up the body immune system so overzealously that the heart gets captured in the crossfire. Whatever the cause, the condition is generally moderate, however can sometimes be serious sufficient to completely jeopardize the heart, needing lifesaving interventions consisting of ventilators or organ transplants; in extremely uncommon cases, it’s deadly.

That is distinctly not what we’re seeing in the CDC’s current reports. The company has actually verified more than 500 cases of myocarditis or pericarditis—swelling of the heart itself or of the lining that shrouds it—in individuals more youthful than 30 who just recently got Pfizer-BioNTech’s or Moderna’s two-shot COVID-19 vaccines. These occasions are, up until now, not matching the most frightening variations of the condition, which have been observed with coronavirus infections. Rather, compared with more normal cases of myocarditis, the ones connected to the vaccines, usually, include briefer signs and faster healings, even with less intrusive treatments. Still, the occurrences are appearing in the couple of days that follow each vaccine’s 2nd dosage at higher-than-expected rates, specifically in young boys and boys, and nobody is yet sure why.

The CDC’s Advisory Committee on Immunization Practices, or ACIP, fulfilled recently to weigh the threats and advantages of keeping the vaccines in flow amongst the country’s qualified youngest. It quickly reached a familiar decision: The advantages of immunization far exceed the possible downsides of these adverse effects and others. Days later on, the FDA added an alerting about the uncommon occasions onto its truth sheets for the vaccines. The majority of the specialists I spoke with enthusiastically backed both firms’ choices without booking. Vaccines, they stated, stay our most effective protective tool versus the coronavirus; if anything, remaining uninoculated is the larger gamble when it pertains to serious organ swelling. However numerous of them likewise kept in mind that this specific adverse effects, and the nation’s reaction to it, represents a brand-new kind of stumbling block for our shots.

The shots themselves, which are excellent, haven’t changed. But the context in which we’re deploying them has. This potential side effect is the first to concentrate like this in children, who are still relatively new to COVID-19 vaccination. Post-vaccine myocarditis still isn’t well defined; neither are the full consequences of pediatric COVID-19. For more than a year now, the pandemic has forced people to pit a pile of risky unknowns against another pile of risky unknowns, but anything that concerns kids’ health is bound to make tensions run particularly high. A recent Kaiser Family Foundation poll found that recent news of heart problems was a top-of-mind concern for many parents, who are often less likely to vaccinate their children than themselves.

The country’s situation is also very different from when the vaccines first arrived. Different types of shots are probably on their way, offering alternative routes to vaccination, perhaps without this particular risk. More versions of the virus are on our doorstep as well, and experts can’t confidently forecast our fates through the fall and winter. We are, once again, engaged in a game of pandemic chess, one that’s not getting much easier over time. We’re still figuring out the pieces we’re handling, and the crafty opponent on the other side; we’re relearning the rules, and the landscape of our board. And this next round, some of the most prominent players are our kids.


That the recent cases of post-vaccination myocarditis are relatively mild is, to start, “very reassuring,” said Judith Guzman-Cottrill, a pediatric-infectious-disease physician at Oregon Health & Science University (OHSU), who helped identify some of the earliest instances of inflammation back in April. Symptoms have lasted just a couple of days; most of the inflammation has been fairly straightforward to treat. According to Katherine Poehling, a pediatrician at Wake Forest Baptist Medical Center and an ACIP member, no deaths or severe outcomes had been reported at the time of last week’s meeting. “This is not like any myocarditis I’m used to seeing,” said Grace Lee, a pediatrician at Stanford and a member of ACIP. Though most of the identified patients have been hospitalized, “it’s because we wanted to monitor them, out of an abundance of caution,” said Sallie Permar, the chair of pediatrics at Weill Cornell Medicine and New York–Presbyterian Komansky Children’s Hospital. Many of these patients were discharged after receiving little more than over-the-counter pain medication as therapy. “Even the kids are asking, ‘Why am I going to the hospital?’” Permar said.

But vaccine-induced heart inflammation of any severity still warrants concern, especially without a known root cause. Myocarditis and pericarditis, which mysteriously skew young and male, can arise from an array of triggers, including bacteria and fungi as well as medications and autoimmune disease, but many cases go entirely unexplained. There’s no curative, or even standard, treatment for either condition; doctors try to manage symptoms and tamp down inflammation, said John Jarcho, a cardiovascular-medicine specialist at Brigham and Women’s Hospital, in Boston.

Cases related to vaccines are more puzzling still. Only a few immunizations have previously been linked to heart inflammation, among them the smallpox vaccine, which looks nothing like the jabs we’re doling out now. Researchers remain unsure what’s triggering the body to act out, or which children, especially which adolescent boys, might be most vulnerable. Mark Slifka, a vaccinologist at OHSU, told me he suspects the inflammation is caused by a bit of friendly fire—an extreme manifestation of the side effects already known to come with the Pfizer and Moderna vaccines, especially after the second injection. Perhaps immune cells are pumping out excessive alarm signals that marshal forces to the heart, or maybe the body’s defenders, confused by a vaccine ingredient, mistakenly wallop cardiac tissue. (Kids’ immune systems are generally feistier than adults’.)

We also don’t yet know whether these brief bouts of inflammation are leaving lasting damage, perhaps through subtle scarring of the heart, said Jeremy Asnes, a co-director of Yale New Haven Children’s Hospital Heart Center. His team has seen about a dozen adolescents with the conditions and will conduct follow-ups over the next several months. Guzman-Cottrill is doing the same in Oregon.

All of these factors make the risk of this complication tough to quantify, and several researchers have criticized the CDC’s recent evaluation. But most of the experts I spoke with said that the calculations still come out strongly in favor of vaccination, in part because of another set of disconcerting ambiguities, this time on the side of the virus.

SARS-CoV-2 does, on average, cause less severe disease in kids. But less is no longer a terribly comforting qualifier. Millions of young people have been infected; thousands  have been hospitalized; more than 300 younger than age 18 have died. We still don’t know how many kids hit by the virus will go on to develop long COVID, and the CDC has also logged more than 4,000 cases of a severe inflammatory complication called MIS-C. This condition can itself involve severe myocarditis—far worse than the cases that typically follow vaccination—and seems to carry a 1 percent fatality rate. It also disproportionately impacts people of color. “If you think about all the risks that come with getting COVID itself, those are way more common” than the very low myocarditis rates we’re seeing with vaccines, Permar told me. “If you’re playing the numbers, every time you would choose to vaccinate your child to prevent disease.” Thomas Murray, a pediatric infectious disease physician and the associate medical director for infection prevention at Yale New Haven Children’s Hospital, agreed: “If I had to take my chances, I’d rather take my chances with the adverse effects of myocarditis down the road than with an actual viral infection.”

Not all experts have taken the same stance; some have argued that there’s no rush to vaccinate kids. Coronavirus transmission in the United States has, after all, been dropping for months. But while absolute numbers of infections are down, the face of COVID-19 in this country has shifted. With vaccines concentrated among older adults, younger individuals are now shouldering more of the nation’s coronavirus burden: About a third of the infections reported to the CDC in May were in people ages 12 to 29, many of them unvaccinated. And the low spread we’re seeing right now won’t necessarily hold against the rise of highly contagious variants like Delta. It’s a terrible time to lose the momentum we’ve gained. “I’m not looking at transmission rates now,” Guzman-Cottrill told me. “I’m looking at what might happen in fall and winter.” Vaccination would shield kids, as well as those around them; immunizing more today means better protection later, even if we can’t yet see the threats on the horizon.


Doctors are carefully monitoring new cases that come their way. If the inflammation they’re seeing continues to be mild, Asnes said, the people who experience it might be able to leave the hospital even earlier, or never check in at all. But if there’s an unexpected uptick in severity, experts will reassess.

More vaccine options could also change these calculations. For now, Pfizer is the only COVID-19 shot that can be used in children. But other vaccines with gentler side-effect profiles, including those from J&J and Novavax, could be easier on the heart, OHSU’s Slifka said.

In the interim, some experts have floated the notion of tinkering with Pfizer and Moderna dosing to safeguard younger heart tissue. Vinay Prasad, a hematologist-oncologist at UC San Francisco who has been very critical of the CDC’s evaluation of heart inflammation, told me he’d like to see the agency consider skipping second doses, or trimming doses down for at-risk populations. Neither of those strategies has been rigorously tested, though. Dose-reducing revisions run the risk of blunting protection, which might have contributed to the failure of the CureVac mRNA vaccine. Forgoing second doses could also backfire: Repeat shots seem crucial for conferring strong protection against variants like Delta.

Then again, kids aren’t just tiny adults, and adapting vaccines to their needs isn’t just a matter of bending down to stick a needle in a shorter, smaller person. Youthful immune systems react more enthusiastically to certain inoculations, which can mean more side effects, or simply that they need less vaccine to mount a defense. Numerous existing vaccines, such as the ones we use for chickenpox/shingles and tick-borne encephalitis, come in lower doses for children; Moderna and Pfizer are adopting this same strategy in their clinical trials for kids under 12. As they’re ushered into younger populations, our vaccines can be expected to undergo some growing pains.

The key, experts told me, is to stay flexible. Everyone’s chess board will end up looking a little different. Yale’s Murray, whose two older children have already gotten their shots, told me he and his younger son, who will soon turn 12, will be talking through the risks. However Murray is firm on one thing: “I don’t want him to have to worry about him getting COVID.” So, he added, “We’ll see what we need to do to get him vaccinated.” Cornell’s Permar told me her family heard of the myocarditis reports the day before her 12-year-old son, Sam, was scheduled to receive his second dose of Pfizer. “We didn’t question it,” she stated. “Looking at the numbers, there are so many more benefits of my son getting the vaccine.” Still, she kept a close eye on him for a few days after his shot.

Jobber Wiki author Frank Long included to this report.