Covid-19 survivors who receive a first dose of Covid-19 vaccine generate immune responses that can make a second injection unnecessary, potentially releasing a limited vaccine supply for more people, several new research papers suggest.
The study, while preliminary, found that the previously infected people quickly and at dramatically higher levels generated protection against the disease after an initial shot of the current two-shot regimens compared to people who had been vaccinated but had not been ill.
‘Everyone should get vaccinated. Not everyone needs two injections, ”said Viviana Simon, professor of microbiology at the Icahn School of Medicine in Mount Sinai in New York and author of one study. “As long as we can’t deliver that much vaccine to everyone who wants it, I think it’s an important consideration.”
The research, which was posted on preprint servers but has not been peer-reviewed or published in a scientific journal, is because other findings in the two-step regimen for healthy members of the general population highlight the immune benefits after the first injection. On Friday, researchers in Israel reported that a single injection of the vaccine from Pfizer Inc. and BioNTech SE is 85% effective in the prevention of symptomatic diseases 15 to 28 days after administration.
Late-stage clinical studies of two-dose vaccines by Pfizer and BioNTech, as well as by Moderna Inc., have shown that their injections are safe and highly protective against Covid-19 when given in two doses several weeks apart. However, Pfizer’s study ruled out individuals with symptomatic Covid-19, and Moderna ruled out people with a previously known infection, prompting researchers to see how the immune systems of people who were previously sick responded.