‘Real world’ study by CDC shows Pfizer and Moderna vaccines were 90% effective

A new study suggests the messenger RNA vaccines produced by Moderna and the Pfizer-BioNTech partnership appeared to be 90% effective in preventing Covid-19 infection in a real-world setting. The study was released in Morbidity and Mortality Weekly Report, an online journal published by the Centers for Disease Control and Prevention. The study followed nearly 4,000 health care workers, first responders, and other essential workers in eight U.S. locations as the first Covid vaccines were rolled out starting in December. Participants were tested weekly to look for all cases of Covid infection, even asymptomatic ones. In the period from Dec. 14, 2020, to March 13, 2021, nearly 75% of the workers in the cohort received at least one dose of one of the mRNA vaccines. Both are given in a two-dose schedule. There were 161 Covid infections in the unvaccinated workers, compared with 16 in workers who had received only one dose by the time...