(CNN) A fresh batch of data from a big study of health care workers across the United States helped prompt the US Centers for Disease Control and Prevention to say fully vaccinated people can go without masks in most circumstances, the agency said Friday.
The study found use of the Moderna and Pfizer COVID-19 vaccines provided 94% protection for the frontline workers immunized at the beginning of the vaccine rollout. A single dose provided 82% protection, the CDC-led team reported in the agencys weekly report, the MMWR.
This assessment, conducted in a different study network with a larger sample size from across a broader geographic area than in the clinical trials, independently confirms U.S. vaccine effectiveness findings among health care workers that were first reported March 29, the CDC said in a statement.
This report provided the most compelling information to date that COVID-19 vaccines were performing as expected in the real world, CDC Director Dr. Rochelle Walensky said in the statement.
This study, added to the many studies that preceded it, was pivotal to CDC changing its recommendations for those who are fully vaccinated against COVID-19,” she added.
More about the study: It involved more than 1,800 workers and compared people who tested positive for coronavirus to those who tested negative.
Health care personnel are at high risk for COVID-19, the report reads. The early distribution of two mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna) to health care personnel provided an opportunity to examine vaccine effectiveness in a real-world setting, they added.
The first U.S. multisite test-negative design vaccine effectiveness study among HCP found a single dose of Pfizer-BioNTech or Moderna COVID-19 vaccines to be 82% effective against symptomatic COVID-19 and 2 doses to be 94% effective,” the report continued.
Read more updated here.
