“No way” was my reaction in February 2020 when asked if I’d take the first round of vaccines for COVID-19. The vaccines were still being developed and, as a historian, I knew too much about the problems that accompanied early vaccination attempts. These include a notorious episode in 1955 when Cutter Laboratories released several lots of the newly developed polio vaccine that were faulty despite having passed government safety tests. The contaminated doses led to more than 40,000 children developing some form of the disease.
By February 2021, however, my view had shifted and I eagerly sought my first opportunity to get vaccinated. I was then fascinated by what led to my quick and comfortable COVID-19 about-face, especially because I was researching an episode in US history in which scientists failed to persuade the public about the safety of a nuclear reactor, amplifying rather than lessening fears by treating safety as a technical issue – as a matter of numbers. (I will not be talking about compulsory versus voluntary vaccination programmes, which involve other issues.)
All those carrot-and-stick strategies intended to encourage people to get vaccinations – lotteries, musical and sports events, videos of politicians and influencers – would not by themselves have worked on me. In my case it came to make sense to me that I should be vaccinated. I knew to look for help to the Greek philosopher Aristotle, who in his Rhetoric had spelled out three dimensions of how persuasion comes about, for which the Greek terms are ethos, logos, and pathos.