The CDC revised its COVID-19 vaccination data for Americans 65 and older after state officials discovered the agency over-counted the number of people who received first doses, Bloomberg reported Dec. 18.
The CDC reduced the percentage of people 65 and older who received one dose from 99.9 percent to 95 percent, keeping raw vaccination totals unchanged.
The CDC's vaccine tracker had shown for nearly a month that 99.9 percent of adults in this age range had received at least one COVID-19 shot. But some health experts noted that the dashboard showed more seniors being partially vaccinated (55.4 million as of Dec. 5) than there are people in that age group (54.1 million), according to U.S. Census data.
In a statement to Bloomberg, the CDC acknowledged it had consistently and incorrectly counted booster shots and second doses as first doses, meaning the number of fully vaccinated and unvaccinated people in the U.S. are undercounted. The precise number of vaccinations miscounted is unclear, though data revisions from Illinois, Pennsylvania and West Virginia suggest that millions of unvaccinated people in the U.S. have mistakenly been counted as having at least one dose, according to Bloomberg.
"Given the complex nature of vaccine administration and data reporting in the United States, CDC has been actively working with partners at state and local levels to enhance the quality of vaccine data," the CDC told the publication.
View the full report here.