A single dose of Pfizer, Moderna vaccine almost as effective as two

Single doses of Pfizer and Moderna vaccines are more than 92% effective in preventing COVID-19 disease after two weeks, Canadian researchers now say.

FDA’s own data shows that a single injection of the BioNTech-Pfizer vaccine is 92.6% effective after two weeks and that a single dose of Moderna is 92.1% effective, note researchers in New England Journal of Medicine.

Getting that second injection of Pfizer’s vaccine increases efficacy only marginally, to 94 percent, according to a separate study based on actual data from Israel’s immunization program.

And so the second prescribed doses should instead be administered to those in priority groups who are still awaiting their first vaccine, “given the current shortage of vaccines,” the researchers insist.

“With such a highly protective first dose, the benefits derived from a limited vaccine supply could be maximized by postponing the second doses until all members of the priority group are offered at least one dose,” the researchers explain. in a letter to the editors of the NEJM.

“There may be uncertainty about how long the protection will last with a single dose,” the researchers said.

“But administering a second dose within a month of the first, as recommended, provides little additional benefit in the short term, while high-risk people who might have received a first dose with this vaccine supply are left 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 santé publique du Québec in Quebec.

In a letter to the NEJM in response to the two researchers, Pfizer stressed that “alternative dosing regimens” have yet to be evaluated.