Pfizer and Moderna vaccines against COVID-19 They have effectively prevented new coronavirus infections, not just diseases, with substantial protection evident two weeks after the first dose, US government researchers said.
Two doses of the vaccines provide up to 90 percent protection against infection, according to data from the U.S. Centers for Disease Control and Prevention (CDC) study released Monday.
Previous clinical studies had shown that vaccines also prevent illness, hospitalization and death.
The study adds to the evidence that the new vaccines made with messenger RNA technology they actually reduce the spread of the virus under real conditions. A previous study in Israel found that a single dose of the Pfizer vaccine reduced infections by up to 85 percent.
CDC studied a group of approximately 4,000 front-line workers, including medical personnel, first responders, teachers, and service workers. from mid-December to mid-Marchas vaccines have been widely implemented.
These groups were among the first to be vaccinated along with the frail elderly because of their risk of exposure to the virus.
Participants were tested weekly for the SARS-CoV-2 virus and questioned for reports of symptoms. The researchers compared the frequency of COVID-19 infections before and after vaccines to estimate how effective the injections were in preventing the spread of the pathogen, regardless of whether people felt sick or not.
Both the Pfizer and Moderna vaccines require two doses, separated by weeks. Two weeks after the first dose, the injections were found to prevent 80 percent of infections, which increased to 90 percent two weeks after the second dose, when people were considered fully immunized.