Update to the Vaccine Safety and Efficacy Article

New study on myo and pericarditis

An extensive study came out yesterday (https://jamanetwork.com/journals/jamacardiology/fullarticle/2791253?guestAccessKey=b76ffbb1-d5c4-4f00-add1-a30d0dce45e7) that looked at incidence of myocarditis or pericarditis in individuals of all age groups that had taken one, two or three shots of the Pfizer, Moderna or AstraZeneca vaccines and suggests the risks involved are something one should take into consideration. They use mathematical modeling to predict “person years of follow up” (a term I explained in yesterday’s post), which is important in addressing possible future incidence of vaccine-related heart ailments, but also has the same problems that other epidemiological models have. Because this was a cohort study, not a randomized control study like the clinical trials were, the control group consists of people in the population that are not vaccinated, the reasons for which are not known; thus, the investigators have to account for the fact that they weren’t given a placebo and then followed closely for the same amount of time that those given vaccines. Because the vaccines are new, the person-years of follow up for vaccine recipients is smaller than for the unvaccinated group, even though for the Pfizer vaccine there were more individuals (over 15 million) than in the unvaccinated group (4.3 million). What that means is that the rate of myocarditis or pericarditis per person isn’t directly comparable between the two groups because, for the vaccinated people we are interested in that which occurred during the time after the shot. It’s completely legitimate to try to correct for the fact that you are comparing random incidence of these heart ailments in the population at-large to that occurring from the vaccine. However, you still have to understand that the risk ratios that are given in the table reflect a real numerator (number of myocarditis or pericarditis cases) with an estimated denominator. Hopefully, that makes sense.

To put real numbers to this concept, let’s look at myocarditis in Table 2 of the paper. There were a total of 723 reports of myocarditis in the unvaccinated groups, which corresponds to 0.017%. There were 259 incidences in those who received at least 1 shot of the Pfizer vaccine, which is .002%, and there were 88 incidences in those receiving at least 1 Moderna shot, which was 0.005 % . Hopefully, you can see how the naysayers would claim the incidence of myocarditis is not higher in vaccinated than unvaccinated individuals, and this is why it was so important that they used modeling to predict what how many incidents might occur if you were monitoring over a longer period of time-thus the correction for person-years. What I am not qualified to critique is the validity of their modeling, but they don’t have an obviously incorrect assumption like the models for predicting COVID transmission did (the inflated asymptomatic transmission rate). There were also fewer unvaccinated individuals than there were vaccinated ones, and it is possible that those who had not been vaccinated had pre-existing issues, such that the baseline incidence of these conditions was artificially higher in this age group.

Nonetheless, when corrected for person years of follow-up the authors predicted an 8-fold increase in myocarditis for the Moderna shot and a 2-fold increase for the Pfizer and AstraZeneca shots. Full disclosure: if the predictive denominator used here were being used in the generation of data that was being touted as a reason for us to stay home, mask up and get a shot, I would be very critical of it. However, in this case mathematical modeling is being used to predict possible adverse events such that people deciding whether to take a medical treatment have more information. This is the study I was saying needed to be done in the article I wrote yesterday. It came out while I was writing…