Invited Commentary: Thirty-five Years of Leaky Vaccines

Over the past 35 years, the term "leaky vaccine" has gained widespread use in both mathematical modeling and epidemiologic methods for evaluating vaccines. Here we present a short history as we recall it of how the term was coined in the context of the history of sporozoite malaria vaccines that were thought to be possibly leaky in the 1980s. We draw a contrast with the all-or-none vaccine mechanism and review a few consequences for study design and population level effects. We invite readers to contribute information covering the time period preceding our memories in the 1980s as we may have overlooked something.