Is the Second Shot Giving Young Men a Dangerous Heart Condition?

A health worker administers the COVID-19 vaccine to an Israeli at mobile clinic parked near a bar in Tel Aviv. Photo: Gil Cohen-Magen/AFP via Getty Images

An official Israeli report released Tuesday found a striking correlation between COVID-19 mRNA vaccinations and a spike in cases of a heart-inflammation condition in young males, which appears likely to lead the country to revisit its recommendation that children receive two doses of the vaccine.

The report found over 110 cases of myocarditis around the time of vaccination, 95 of which occurred following the second of Pfizer’s two-dose regimen. This translates to a rate of roughly one in 50,000. However, most of the people who developed the heart condition were young men, with a particularly high incidence for those aged 16 to 24, putting their rate at around one in 5,000. “These findings raise the likelihood of a causal link between the vaccine and myocarditis,” states the report presented by a committee that was appointed by the country’s health ministry to investigate a possible connection between myocarditis and the vaccines. Myocarditis can generally go away on its own, though it can also be serious, with lasting health consequences, and is sometimes even fatal.

A detailed analysis at Hadassah Medical Center, a major hospital serving the greater Jerusalem area, found that cases of myocarditis at the facility were five to 25 times the normal number over the same time span in previous years, Dror Mevorach, the head of internal medicine and the COVID-19 ward at Hadassah, told Intelligencer. This potentially puts the rate as high as one in 3,000 to one in 6,000 vaccinated young men, he said. Mevorach, who also headed the national committee to investigate the myocarditis link, said that over a span of three months the hospital saw 20 cases of myocarditis, when it typically sees only four; 19 of the 20 cases were young males, ages 16 to 30. Eighteen of the 20 cases presented within four days of the second vaccine dose. The patients all had chest pain or difficulty breathing, ruling out that the condition was asymptomatic and caught inadvertently by general tests, Mevorach said. Only two patients of the 20 had evidence of past infection, eliminating any correlation with COVID-19 itself, rather than the vaccine.

A possible link between myocarditis and the mRNA vaccines has been in the news since earlier this year, when initial reports of vaccinated people experiencing the heart condition surfaced from Israel, and in the U.S military. Last month, Connecticut’s health commissioner said there were at least 18 teens and young adults in the state who developed heart problems following COVID-19 vaccination. Last week, the top health officer in King County, Washington, said his county had 14 cases of myocarditis or pericarditis (inflammation of the outer lining of the heart) following vaccination. “It’s unclear if the cases are linked to vaccination,” he said. The ages ranged from 16 to 42, and all but two cases were males.

It’s important to stress that the Connecticut and Washington reports, among many others, are anecdotal. And the Centers for Disease Control and Prevention’s vaccine safety group on May 17 said in a report that “rates of myocarditis reports in the window following COVID-19 vaccination have not differed from expected baseline rates.” Yet, the statement continued, “members felt that information about reports of myocarditis should be communicated to providers.”

To understand whether there is a real correlation between myocarditis and the vaccines, and if so its degree of prevalence, is, unfortunately, not an exact science. For starters, the United States lacks a system for measuring such data with precision. “There is no way for CDC to query electronic records for myocarditis,” said Shira Doron, an infectious-diseases physician and hospital epidemiologist at Tufts Medical Center in Boston. Instead, federal agencies largely rely on the Vaccine Adverse Event Reporting System (VAERS) for tracking serious adverse events following vaccinations. But the system is passive, meaning that reports, which can be submitted by anyone, are voluntary. As such, a paper, published by authors from the CDC and FDA, explains, “VAERS data cannot be used to determine if a vaccine caused an adverse event.”

Instead, the paper noted, the database is “a safety-signal detection and hypothesis-generating system,” which is still valuable. Putting a notice of a potential problem in the media, as the CDC has done with myocarditis, Doron said, is a good way to increase case findings, and the higher the number, the more reliable it is. Nevertheless, the numbers in VAERS are imperfect and can be over- or underestimates.

Considering the known limitations of our tracking systems, the CDC’s declaration that the rates of myocarditis following vaccination are no higher than baseline projects an unfounded certitude. First, the specific rate of myocarditis following vaccinations is unknown because, as was noted, the reporting system is not comprehensive. Second, there is no baseline rate of myocarditis to compare such events to. Some estimates suggest the baseline for myocarditis is between ten and 20 cases per 100,000 persons. Marc Richmond, a pediatric cardiologist at Columbia University Medical Center, said he thinks the baseline might be around three per 100,000, but that “we don’t actually know the rate.” Nevertheless, he said, there does appear to be a small sign about the correlation between the vaccine and myocarditis. But, at the moment, it’s too hard to tell one way or the other.

In the face of growing concerns about myocarditis, last week the CDC posted a statement saying it “continues to recommend COVID-19 vaccination for everyone 12 years of age and older. The known and potential benefits of COVID-19 vaccination outweigh the known and potential risks, including the possible risk of myocarditis or pericarditis.”

Mevorach, the Israeli physician, suggested that it’s possible his committee found a seemingly definitive link while the U.S. has not because Israel is a small country and it’s easier within their system to find a signal faster. He predicts the CDC will change its assessment. As it stands, recent reports from Israel suggest that because of the side effects, and the country’s low rate of COVID-19, the health ministry is going to change its recommendation from two doses for pediatric vaccination to one dose, or perhaps no specified dose schedule. Unlike the U.S., Israel has held off on vaccinating 12- to 15-year-olds. The health ministry announced today that it will begin to allow that age group to be vaccinated next week.

There is ambiguity about the balance of costs and benefits to kids to get vaccinated, at least right now, on this schedule, according to a number of experts. This is why, in part, some epidemiologists and others have suggested that children do not meet the criteria of an “emergency-use authorization” of the vaccines, unlike most adults. The risk of COVID-19 itself to children is low, and as I reported in late May, two studies found that pediatric hospitalization rates for the disease have been over-counted by at least 40 percent. So it’s hard to run the risk-benefit calculation with any degree of clarity.

Indeed, during the meeting of VRBPAC, the advisory committee to the FDA for vaccine approvals, several members adamantly objected to the initial EUA beginning at age 16, rather than, at minimum, age 18. “I do not believe we have sufficient data for 16- and 17 year-olds … they do not get very sick, and are seldom hospitalized,” one member said, which was typical of the critical comments. Cody Meissner, one of the committee members, and chief of the division of pediatric infectious disease at Tufts School of Medicine, told Intelligencer that he didn’t vote in favor of the EUA because fewer than 100 adolescents aged 16 and 17 got vaccinated in the trial. Five out of 22 members ultimately did not vote in favor of the general EUA for the Pfizer vaccine, which the FDA approved in December.

The clinical trial for 12- to 15-year-olds included a little over 2,000 participants, half of whom were in the placebo group. If an adverse event such as myocarditis occurs in one out of every 3,000 to 6,000 young males, as Mevorach estimates from his data, a trial with 1,000 people actually receiving the vaccine might not even see that event. In May, the FDA did not invite the advisory committee back when it extended the EUA for 12- to 15-year-olds.

The good news is the data show that the absolute risk from COVID-19 to children is extremely small. Pediatric mortality is on par with or less than that from influenza in recent seasons, and the already very low hospitalization numbers, as noted, were found to be significantly over-counted. Conversely, a number of experts Intelligencer spoke with believe, and at least preliminarily the data suggest, that the absolute risks from the vaccine to children are likely extremely small as well.

Nevertheless, despite the CDC’s assurances, taking into account the dearth and opacity of the data in the U.S., the Israeli report may be worth considering.

Is the Second Shot Giving Young Men a Heart Condition?