June 29, 2021 -- More than 1 in 10 people have missed their second COVID-19 vaccine dose in the U.S., and the gap is growing as the vaccination rollout continues.

About 88% of those who are eligible for a second dose have received one, CNN reported, which is down from 92% in the spring.

Public health officials are trying to close the gap and encourage people to get their second dose as the contagious Delta variant spreads across the country. The Delta variant, which was first identified in India and led to surges in India and the U.K., now accounts for about 20% of new COVID-19 cases in the U.S.

Recent studies have shown that vaccines are about 88% effective against the Delta variant after two doses, as compared with 33% efficacy after one dose, CNN reported.

“As this virus has mutated, there are versions of it which are better able to escape some of the immune protection that we get from the vaccine,” Vivek Murthy, MD, the U.S. surgeon general, told CNN.

“The key is, get vaccinated,” he said. “Get both doses.”

Those who have received the Pfizer vaccine should get the second dose 21 days after the first shot, and those who have received the Moderna vaccine should get the second dose 28 days after the first shot.

More than 153 million people in the U.S. are considered fully vaccinated, according to the latest tally from the CDC. About 66% of U.S. adults have received at least one vaccine dose, and 57% are fully vaccinated.

However, about 11% of Americans who are eligible to receive a second dose — or about 15 million people — haven’t completed their vaccine series, CNN reported. Adults under age 30 were most likely to have skipped the second dose.

Some states also have lower rates of fully vaccinated residents, which could lead to pockets of outbreaks, according to Good Morning America. Five states — Alabama, Arkansas, Missouri, Oklahoma and Utah — have seen an increase in COVID-19 cases in recent weeks and have full-vaccination rates lower than the national average.

“I would encourage all Americans, to get your first shot and when you’re due for your second, get your second shot and you’ll be protected against this Delta variant,” Rochelle Walensky, MD, director of the CDC, told GMA.

“As worrisome as this Delta strain is with regard to its hyper-transmissibility, our vaccines work,” she said. “They are working, and they require two doses or to be fully vaccinated to work.”

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CNN: “More than 1 in 10 people have missed their second dose of Covid-19 vaccine.”

CDC: “COVID-19 Vaccinations in the United States.”

Good Morning America: “CDC director warns delta variant could soon become dominant coronavirus strain in US.”

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