Vaccine efficacy probable against COVID-19 variants
Larry L. Luchsinger, Christopher D. Hillyer
Abstract
The U.S. Food and Drug Administration (FDA) emergency use authorization of three vaccines, all of which have shown greater than 85% effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (1–3), has provided the public with the hope of ending the global COVID-19 pandemic. However, recent outbreaks of more transmissible variant SARS-CoV-2 strains that harbor mutations in the spike protein—the critical viral target of immune responses produced by the vaccines (1–3)—has invited a dour outlook on the vaccines' continued efficacy (4). The trepidation is based on the prompt compilation of in vitro data that demonstrate as much as 10-fold reduction in neutralization antibody (NAb) activity in vaccinated samples against mutant spike protein pseudovirus (5, 6), which is thought to be an important metric of acquired immunity (7). Although reports of NAb reduction are alarming in magnitude, the proof of vaccine effectiveness can only be measured definitively by challenging vaccinated subjects with infection.