Pfizer's Shot and Teen Heart Risks Need Study. Don't Panic.

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With the U.S. and other countries now vaccinating adolescents, Tuesday’s report from Israeli scientists of a probable link between the Covid-19 shot developed by Pfizer Inc. and BioNTech SE and rare cases of heart inflammation in young men is understandably concerning. Parents worry about their kids, and public health officials must treat this possibility seriously without causing undue panic. But the data is limited as of now, to the point where a connection might not exist. And from what we do know, if there is a relationship, it doesn't appear to be dangerous. 

It's not surprising to see new risks like this emerge. Even though Pfizer’s vaccine and others underwent rigorous preapproval study, rare events will occur when you expand the use of vaccines from a few thousand people to millions, and studies extending use to kids tend to be smaller. What public health leaders can hopefully control is the reaction. With careful and transparent communication about evolving data, scary headlines don't have to derail highly effective vaccinations.

Israel, which mostly uses the Pfizer-BioNTech vaccine, first flagged this side effect in April. In findings submitted to the Israeli Ministry of Health, a investigatory panel reported 275 cases of heart inflammation — a condition known as myocarditis — between December and May. Of those, 148 occurred within a month of vaccination, with most occurring relatively quickly after the second dose. (To put that number in context, Israel fully vaccinated around 5 million people in that period.) The events occurred at a higher rate in young men, and almost all of the cases were mild and resolved quickly. While myocarditis can cause shortness of breath, chest pain or heart flutters, mild cases often only require treatment with anti-inflammatory drugs. 

After reviewing the report, the Israeli Ministry of Health said it remained confident in the favorable risk-benefit profile of the vaccine, announcing Wednesday that it would expand use to people ages 12 to 15. In the U.S., the Centers for Disease Control and Prevention is investigating the same side effect for both the Pfizer-BioNTech vaccine and Moderna Inc. shot, which uses similar technology, and in the meantime continues to recommend vaccination for those 12 and older. 

More information is needed. According to a write-up in Science Magazine, the Israeli report suggests that the incidence of myocarditis in vaccinated young men is five to 25 times higher than the background rate. The CDC is a bit less definitive. It’s examining a similar trend, but as of May 24 myocarditis cases in vaccinated people are only higher than usual in one of two key safety databases. With second Pfizer shots coming up in the next month for many young Americans, the CDC needs to keep a close eye on side effects and keep the public updated. Meanwhile, the complete publication of Israel's results and more data from elsewhere would go a long way toward evaluating a causal relationship. 

Side effects in younger people deserve careful attention because they have a lower risk of bad outcomes from Covid-19. However, given the benefits of broad vaccination in keeping total cases down and the possible long-term effects of infection, there should be a high bar to limiting inoculations.

At the least, a more established link or an increase in myocarditis cases would call for more active surveillance and guidance for doctors, and for providers to let younger people and their guardians know what symptoms to watch, even if the risks are modest. Yes, it might spook some parents and potential recipients. But it’s better than letting them be surprised by symptoms that can be scary without context. In addition, active surveillance could help determine if there’s a subset of people at risk of more serious inflammation and inform research into whether different doses or scheduling might mitigate the effect.

Tuesday’s report won’t be the last notice of a new vaccine side effect. Getting the response to this one right will help to build needed confidence as the global rollout continues. 

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Max Nisen is a Bloomberg Opinion columnist covering biotech, pharma and health care. He previously wrote about management and corporate strategy for Quartz and Business Insider.

©2021 Bloomberg L.P.

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