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5 million Americans have missed 2nd COVID-19 vaccine dose, CDC data shows

With the Pfizer and Moderna vaccines, someone isn't considered fully vaccinated until two weeks after their second shot.

WASHINGTON — While the vast majority of Americans are following thru on both rounds of COVID-19 vaccinations, more than 5 million Americans have failed to follow thru on getting a second dose, according to national reports.

The New York Times and ABC News said recent Centers for Disease Control and Prevention data shows that about 8% of Americans who received their first dose of the Pfizer or Moderna mRNA COVID-19 vaccines have missed their second dose during their scheduled windows.

The percentage of people not getting their second dose, according to CDC data, is more than double the 3.4% who missed their second dose in mid-February.

“I’m very worried, because you need that second dose,” said Dr. Paul Offit, a professor at the University of Pennsylvania and a member of the Food and Drug Administration’s vaccine advisory panel told the New York Times.

Dr. John Brownstein, an epidemiologist at Boston Children's Hospital, told ABC News that it isn't clear why so many Americans have missed their second dose. However, he said a few factors could include strong side effects deterring individuals from getting a second shot, work schedules, misinformation or just technical issues that could contribute to the difference.

The New York Times said the second shot data comes from missed counts of vaccines through April 9. It only covers people who got their first Moderna dose by March 7 or a first Pfizer dose by March 14.

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The CDC says anyone who receives their first Pfizer coronavirus vaccine should get their second shot 3 weeks, or 21 days later. For the Moderna shot, Americans are urged to get their shot four weeks later, or 28 days after the first.

Someone isn't considered fully vaccinated until two weeks after their second Pfizer or Moderna vaccine, according to the CDC.

Health officials, however, have said that a second COVID-19 dose may be given up to six weeks after the first dose, but only if necessary. The CDC said that there is “limited information on the effectiveness of receiving your second shot earlier than recommended or later than 6 weeks after the first shot.”

Credit: AP
Empty Pfizer COVID-19 vaccine vials are collected in a tray to be destroyed to prevent them from being resold or refilled, at a vaccination center in the Victor Jara Stadium in Santiago, Chile, Tuesday, March 30, 2021. (AP Photo/Esteban Felix)

Dr. Brownstein told ABC News that the data could miss reports of a second vaccine if someone gets inoculated at two different locations or gets both from a new vaccination site.

"We know IT systems have trouble talking to each other, and you may not get a full picture of an individual," Brownstein told ABC.

About half of all U.S. adults have received one dose of a coronavirus vaccine, according to CDC data. However, some received the single-dose Johnson & Johnson vaccine, which was paused for about a week after health officials learned a handful of rare, but dangerous, blood clots occurred after a few people got the vaccine. Health officials lifted the pause on Saturday.

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The coronavirus is blamed for more than 572,000 deaths in the United States. Across the globe, more than 3 million people have died from the virus, according to a tally from Johns Hopkins University.

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