Scientists split on double-dosing COVID-19 vaccines

• "It will be an absolute disaster if a large number of people only take one dose of the vaccine. It is very likely that protective immunity will wane rapidly in individuals who only take the first shot and efficacy will be nowhere near the 95% reported after the two-dose regimen," tweeted Carlos del Rio, executive associate dean for Emory School of Medicine & Grady Health System.
• "Too much uncertainty in short- and long-term efficacy," agreed Natalie Dean, a professor specializing in vaccine study design at the University of Florida. "And the optics of changing the plan now, for a regimen that hasn't been tested directly, are not great."

But some argue that we should at least study a one-dose regimen.

• "*IF* a single dose DOES work in less vulnerable [people] and IS sufficiently durable (even if not perfect), it might mean vaccinating billions of additional people in 2021 & reach herd immunity faster," tweeted Michael Mina, a professor of epidemiology at Harvard University.