May 14 (UPI) -- The two-dose vaccines from Pfizer-BioNTech and Moderna reduced the risk for symptomatic COVID-19 by 94% among those fully vaccinated, according to data released Friday by the Centers for Disease Control and Prevention.
Those who received just the first dose of the two-shot vaccines had an 82% lower risk for developing symptoms after becoming infected, the data showed.
The findings confirm those of an earlier analysis first released on March 29, the agency said.
"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 P. Walensky said in a 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 said.
The CDC revised its recommendations Thursday regarding mask-wearing and social distancing for fully vaccinated people.
Those who are fully vaccinated no longer need to wear face coverings or maintain 6 feet of distance from others, indoors or outdoors, in most situations, depending on current restrictions in their local areas, the agency said.
In this study, which involved nearly 1,900 healthcare workers at 33 facilities across 25 states, people were considered fully vaccinated seven or more days after they had received their second vaccine dose, according to the CDC.
Understanding vaccine effectiveness among healthcare workers is significant, as they are at higher risk for exposure to the coronavirus because of patient interactions, according to the agency.
Symptomatic illness was reduced by 94% among study participants who were fully vaccinated and by 82% among those who were partially vaccinated, the data showed.
The findings support CDC's recommendation that everyone should get both doses of the two-shot COVID-19 vaccine to get the most protection, the CDC said.