The coronavirus vaccines made by Moderna and Pfizer-BioNTech are proving highly effective at preventing symptomatic and asymptomatic infections under real-world conditions, federal health researchers reported on Monday.
Consistent with clinical trial data, a two-dose regimen prevented 90 percent of infections by two weeks after the second shot. One dose prevented 80 percent of infections by two weeks after vaccination.
There has been debate over whether vaccinated people can still get asymptomatic infections and transmit the virus to others. The study, by researchers at the Centers for Disease Control and Prevention, suggested that transmission may be extremely unlikely, as infections were so rare.