The CDC has estimated that 1.1 million people have received an unauthorized third dose of either Pfizer or Moderna's COVID-19 vaccine, according to an internal CDC document obtained by ABC News.
The publication reported Aug. 10 that the number is likely an undercount because it only included people who received Moderna or Pfizer's shot and got a booster, not those who received Johnson & Johnson's.
It's unclear if the people who got a booster shot did so under the direction of a physician. The FDA has not authorized booster shots, but there have been reports of some physicians encouraging severely immunocompromised people to get them, ABC reported.
The FDA has said it expects to establish a national strategy on booster shots by early September. But the World Health Organization on Aug. 4 called for a moratorium on booster shots until more low-income countries receive access to first doses.
Florida is among the states reporting the highest number of people getting boosters, ABC reported, followed by Ohio, California, Illinois and Tennessee.
The CDC said in a statement to Insider, "We do not comment on leaked documents."
Several people who got an unauthorized booster told Insider they did so out of fear over the delta variant, as well as the fear that Johnson & Johnson's vaccine isn't as effective as mRNA shots.