Because no other whole-virus inactivated vaccine was available for clinical studies (ie, licensed in the EU or UK and accessible for conduct of studies), the comparator chosen in consultation with the study cofunder—the UK Department of Health and Social Care—was the COVID-19 vaccine ChAdOx1-S (recombinant; Oxford-AstraZeneca), a replication-deficient chimpanzee adenoviral vector containing the SARS-CoV-2 structural surface glycoprotein antigen (S protein; nCoV-19) gene.14 The gene discussed is PROS1; the disease is COVID-19.