Pandemic vaccine testing: Combining conventional and challenge studies

Tobias Gerhard, Brian L. Strom, Nir Eyal

Publication Date: 03/16/2022

Early into COVID, human challenge trials were considered, but usually as alternatives to conventional randomized controlled trials. Instead, assessment of authorized COVID vaccines, of further COVID vaccines, and of vaccines against future pandemics should combine both designs, in five different ways, including a wholly novel one that we elaborate, Viz., combining data from both designs to answer a single question.

Though multiple SARS-CoV-2 vaccines are authorized or approved, further testing could help to settle many open questions—how much they block infection and infectiousness by old and new viral strains long after first administration, which dosing and timing regimens are ideal, what are the correlates of vaccine protection, how each compared to natural infection, and how well they work in populations underrepresented among recruits or infection cases in earlier field trials. There also remains enormous value to testing next-generation vaccines, ranging from strain-specific vaccines through universal COVID vaccines to other COVID vaccines that prove even more efficacious at blocking transmission (against some strains), even safer, easier to deliver in resource-poor settings, cheaper, monopoly-breaking, or simply possible to manufacture and distribute to uncovered global populations without undermining manufacture of authorized vaccines…