We read the Correspondence by Günter Kampf1 with surprise, as it appears to argue that the base-rate fallacy2 is, in fact, not a fallacy. In the context of COVID-19 vaccines, the base-rate fallacy is often described as the illusion that vaccines are ineffective because, in highly vaccinated populations, the majority of COVID-19 cases occur among vaccinated people. For example, if a population is 99% vaccinated against a hypothetical virus and 51% of infected individuals have been vaccinated, the base-rate fallacy (falsely) implies that the vaccine is ineffective at preventing infection.