Misleading assertions, unjustified assumptions, and additional limitations of a study by Patone et al., described in the article "Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex"

Abstract

We describe several shortcomings of a study by Patone et al, whose findings were recently published in the American Heart Association Journal Circulation, including the following: * The study's principal conclusion, as initially stated, begins "Overall, the risk of myocarditis is greater after SARS-CoV-2 infection than after COVID-19 vaccination ...." However, Patone et al never attempt to assess the incidence of myocarditis in their study population following SARS-CoV-2 infection. Rather, they make an untenable assumption that all infections occurring in their study population are associated with (reported) positive COVID-19 tests. Using publicly available data from the UK's ONS and NHS, we show that Patone et al's estimates, for the unvaccinated, of myocarditis incidence associated with infection are likely overestimated by a factor of at least 1.58. * The method Patone et al use to compute the incidence of myocarditis among the unvaccinated after a positive COVID test may overestimate risk. The authors assume, without justification, that unvaccinated persons hospitalized during the study period with positive-test-associated myocarditis would later choose to vaccinate with the same probability as unvaccinated persons who have had a positive COVID test. We present a plausibility argument that suggests a possible further exaggeration of myocarditis risk post infection by a factor of 1.5. * Patone et al fail to discuss important limitations of their study with respect to guiding public health recommendations. For instance, at most 0.18% of SARS-CoV-2 cases that contributed to the study's finding were Omicron-variant cases. Thus, the study's estimates of myocarditis risk following infection do not speak to the risk following Omicron infection, which is recognized to be milder than that of previous variants.Comment: New section added (Section 4), conclusion updated (Section 6), 12 pages, 8 figure