CDC: Some people should wait longer for 2nd COVID vaccine

US health officials say some people receiving Pfizer or Moderna COVID-19 vaccines should consider waiting up to eight weeks between the first and second dose

The Centers for Disease Control and Prevention quietly changed its advice on shooting spacing on Tuesday.

They also say the longer wait may help decrease an already rare side effect of vaccination: a form of heart inflammation seen in some young men.

The change will not affect many people, 14 months after the start of the American vaccination campaign. The CDC says 73% of people ages 12 and older have already received two doses of the vaccine.

Also, the suggestion to wait up to two months does not apply to everyone. The original, shorter interval is still recommended for people with weakened immune systems; people aged 65 and over; and anyone in need of rapid protection due to a risk of serious illness.

Dr. William Schaffner, a vaccine expert from Vanderbilt University, said the action made sense.

At the start of the pandemic, there was intense pressure to adopt as tight a vaccination schedule as possible. “The virus was spreading. People were dying. We wanted to get the vaccine into their arms as quickly as possible,” Schaffner said.

Based on studies by vaccine makers, the government allowed Pfizer injections in a series of two doses spaced three weeks apart, and Moderna injections to be spaced four weeks apart.

Some people – mostly teenage and young adult males – have developed a side effect involving inflammation in or around the heart after the second shot. The CDC says that among men ages 18 to 39, the condition has been reported in about 68 per 1 million receiving the second dose of Moderna and about 47 per 1 million receiving the second dose of Pfizer.

Some research has suggested that delaying the second dose for up to eight weeks reduces that risk, CDC officials said.

If people who have already been vaccinated fear they may have achieved less than maximum protection by getting vaccinated on the original schedule, they can allay those fears by getting vaccinated, Schaffner said.

“We have really, really good data that two doses plus the booster provide very strong protection against serious disease,” he said.


The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Department of Science Education. The AP is solely responsible for all content.

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