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- The CDC has said COVID-19 vaccine booster shots are not necessary at this time.
- Studies show vaccines are highly effective at preventing hospitalization and death.
- Still, a government document obtained by ABC News said some people got unauthorized boosters anyway.
- See more stories on Insider's business page.
More than one million Americans have received unauthorized booster shots of a COVID-19 vaccine, according to a government document obtained by ABC News.
In July, the US Centers for Disease Control and Prevention issued a joint statementwith the Food and Drug Administration stressing that "Americans who have been fully vaccinated do not need a booster shot at this time."
But, according to a CDC briefing document, at least 1.1 people have obtained one anyway, ABC News reported.
The outlet suggested that was likely an undercount as it does not capture those who received a Johnson & Johnson, one-dose vaccine and then received a shot of Pfizer or Moderna's inoculation.
In a statement to Insider, the CDC said: "We do not comment on leaked documents."
Speaking to Insider, several people who have received unauthorized booster shots cited fears over the Delta variant - and, in particular, concern that the J&J shot, a more traditional vaccine, is not as effective as those that use mRNA technology.
Studies show all available vaccines are highly effective at preventing hospitalization and death from COVID-19, and greatly reduce the risk of becoming infected in the first place.
Both Moderna and Pfizer, however, have said a third booster shot may be necessary months from now to stave off waning immunity.