Pfizer-BioNTech mRNA BNT162b2 Covid-19 vaccine protection against variants of concern after one versus two doses.

Abstract

Strategies for rolling out vaccination against Coronavirus Disease 2019 (Covid-19) varied across countries. A key question is whether delaying administration of the second vaccine dose to vaccinate the largest number of people in the shortest time, in situations of limited vaccine supplies and high incidence, could avert more disease cases, hospitalizations and deaths than the current protocol of a second dose shortly after the first dose.