Our heroes of Team Reality, Tracy Høeg, Ran Duriseti, and Vinay Prasad, have a letter today in the New England Journey of Medicine entitled: Potential “Healthy Vaccinee Bias” in a Study of BNT162b2 Vaccine against Covid-19.”
They point out a crucial statistical issue in a prominent study by Arbel et al., which reported a 90% decrease in Covid-19 related mortality among participants who received a Pfizer–BioNTech booster shot. In their letter, the authors call out unadjusted confounding factors that may have influenced the study's results, skewing the perception of booster effectiveness.