Suggestions to tweak dosage strategy to overcome a supply crunch are not rooted in solid evidence and hence such a move could put public health at risk, US Food and Drug Administration commissioner Stephen M Hahn said on Monday night.
“We have been following the discussions and news reports about reducing the number of doses, extending the length of time between doses, changing the dose (half dose), or mixing and matching vaccines in order to immunise more people against Covid-19,” he said in a joint statement with Peter Marks, who heads FDA’s vaccine division.
“These are all reasonable questions to consider and evaluate in clinical trials. However, at this time, suggesting changes to the FDA-authorised 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,” they said.
FDA has approved vaccines of Pfizer and Moderna based on data on people who received two doses of vaccine at three or four week intervals during clinical trials. But authorities across the world are considering tweaking their vaccination strategy to immunise maximum number of people even as a supply crunch threatens to clog vaccine administration.
In the UK, too, the regulator has advised vaccinating as many people with the AstraZeneca-Oxford vaccine and delay the second dose until 12 weeks as some scientists believe that single dose, though it might not give protection against the virus, cuts down the risk of infection by 45-50%.
Even US federal officers in charge of Operation Warp Speed initiative to facilitate and accelerate vaccination programme in the country have recommended cutting the Moderna shot to half a dose because of supply issues.