The U.S. government has undercounted the number of Americans who are unvaccinated against COVID-19 by millions, state officials have warned.
Last weekend, the CDC revised a bellwether metric—the share of people 65 and older with at least one shot. The agency reduced the proportion from 99.9%, where it had been capped for weeks, to 95%, without changing its raw shot totals.
The move acknowledged a dynamic state officials have discovered: in collating reams of data on COVID-19 vaccinations, the U.S. has counted too many shots as first doses when they are instead second doses or booster shots.
That means both the fully vaccinated and completely unvaccinated are officially undercounted. The precise number miscounted is unknown, but revisions in data from three states—Illinois, Pennsylvania and West Virginia—found enough over-counting of first shots to indicate millions of unvaccinated people nationally who’ve mistakenly been counted as having received a dose.
Changes to national data on the scale of Pennsylvania’s revisions, for example, would mean increasing the number of Americans who are unvaccinated by more than 10 million.
“The truth is, we have no idea,” said Clay Marsh, West Virginia’s COVID czar.