The CDC changed how it tracks breakthrough COVID-19 cases among fully vaccinated Americans this month, spurring concerns from scientists about the potential for inadequate data, reports Bloomberg.
The agency switched from monitoring all reported breakthrough cases to only ones that result in hospitalization or death as of May 1, Tom Clark, MD, head of the vaccine evaluation unit for the CDC’s vaccine task force, told Bloomberg. The CDC's goal is to improve the quality of data collected for severe cases that have the greatest clinical and public health importance.
Some scientists have said the change may mean missing out on data needed to understand why and how breakthrough cases happen.
"We shouldn't be narrowing the focus, we should be broadening and develop a systematic plan," Eric Topol, director of the Scripps Research Translational Institute in La Jolla, Calif., told Bloomberg.
The CDC opted to change its strategy after finding few concerning patterns in the current data, Dr. Clark said. He added that the agency is also planning future vaccine research to compare disease severity and the frequency of variant infections among vaccinated and unvaccinated participants.
As of April 26, there have been 9,245 reports of breakthrough cases among more than 95 million Americans vaccinated, according to the CDC.