Scientists Are Divided Over Delaying COVID-19 Vaccine Dosing

Amid skyrocketing coronavirus infections, some countries are attempting to stretch limited supplies of COVID-19 vaccines by reducing doses or changing vaccination schedules from those shown to be effective in clinical trials. But data are scarce on the impact of such measures, and scientists are split over whether they are worth the risks, announced an article published by the journal Nature on January 11, 2021.

“It might be fine,” says virologist Dan Barouch at Harvard Medical School in Boston, Massachusetts. “But we should stick with what’s been proven to work because we want it to work. We don’t want to be creative for some unclear benefit and then have an unexpected problem.”

The World Health Organization (WHO) recommended a wait of no more than six weeks between the Pfizer vaccine's first and second doses. “That doesn’t mean it’s a criticism of what any country is doing,” says Alejandro Cravioto, chair of the WHO’s Strategic Advisory Group of Experts on Immunization. “It is just based on the evidence that we have.”

“These are all reasonable questions to consider and evaluate in clinical trials,” said Dr. Stephen M. Hahn, the chief of the U.S. FDA, in a statement released on January 4, 2021. “However, at this time, suggesting changes to the FDA-authorized dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence.”

‘Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from COVID-19.’