Single doses of the Pfizer and Moderna vaccines are more than 92 percent effective in preventing COVID-19 disease after two weeks, according to Canadian researchers.
The FDA’s own data show that a single ingestion of the BioNTech-Pfizer vaccine is 92.6 percent effective after two weeks, and a single Moderna injection is 92.1 percent effective, say the researchers in the New England Journal of Medicine.
Getting the second survey of Pfizer’s vaccine increases efficacy only slightly to 94 percent, according to a separate study based on actual data from Israel’s vaccination program.
And therefore, the prescribed second doses should instead be given to those in priority groups who are still waiting for their first shot, ‘given the current shortage of vaccine’, the researchers insist.
“With such an extremely protective first dose, the benefits derived from a scarce stock of vaccine can be maximized by postponing second doses until all priority group members are offered at least one dose,” the researchers said in a letter to the NEJM editors.
“There may be uncertainty about the duration of protection with a single dose,” the researchers said.
“However, administering a second dose within one month after the first, as recommended, offers little benefit in the short term, while leaving high-risk individuals who could receive a first dose with the vaccine stock completely unprotected.”
The letter was written by Dr Danuta M. Skowronski of the British Columbia Center for Disease Control in Vancouver and Dr Gaston De Serres of the Institut National de Sante Publique du Quebec in Quebec City.
In a letter to NEJM responding to the two researchers, Pfizer stressed that ‘alternative dosing regimens’ have yet to be evaluated.