US Considers Lengthening Gap Between First 2 COVID Shots to 8 Weeks

By Michael Erman

February 07, 2022

NEW YORK (Reuters) - U.S. health officials on Friday said they are considering lengthening the recommended interval between the first two doses of the most widely used COVID-19 vaccines to eight weeks to lower the risk of heart inflammation and improve their effectiveness.

Dr. Sara Oliver, an official at the U.S. Centers for Disease Control and Prevention (CDC), said the agency was considering making the recommendation for Moderna and Pfizer/BioNTech shots during a meeting of the Advisory Committee on Immunization Practices, a panel of outside advisers to the CDC.

In the United States, the recommended interval between the first two shots of Pfizer's vaccine is three weeks and for Moderna's, four.

In her presentation, Dr. Oliver said an extended interval appears to reduce the risk of already rare cases of myocarditis, and that the lowest rates of heart inflammation following vaccination occur if the vaccines are given eight weeks apart.

Myocarditis is a rare side effect seen with mRNA vaccines - the technology behind both the Pfizer/BioNTech and Moderna shots. It appears to be more common among young men.

Oliver also said the extended interval appears to increase vaccine efficacy.

Canadian health officials had presented data to the group earlier in the day about why they had settled on a recommended eight-week interval between shots of the two vaccines.