CDC Updates COVID-19 Vaccine Timeline to Reduce Myocarditis Risk

In updating their COVID-19 vaccine guidelines on Tuesday, the US Centers for Disease Control and Prevention said that some people may wait up to 8 weeks before receiving their second dose of Pfizer-BioNTech or Moderna.

Previous recommendations stated the second vaccine should be administered after 3 weeks for Pfizer-BioNTech, and after 4 weeks for Moderna. The impetus for extending the time between first and second doses is to decrease the slight risk of myocarditis in vulnerable populations.

The CDC wrote, “While absolute risk remains small, the relative risk for myocarditis is higher for males ages 12-39 years, and this risk might be reduced by extending the interval between the first and second dose.” They cited studies that showed adolescents and young adults “have shown the small risk of myocarditis associated with mRNA COVID-19 vaccines might be reduced and peak antibody responses and vaccine effectiveness may be increased with an interval longer than 4 weeks.”

There is no benefit to waiting longer than 8 weeks in between first and second doses, however. The CDC noted the shorter interval between first and second dosages is still recommended for adults 65 years and older, immunocompromised people, and anyone who needs increased protection due to concerns regarding severe disease or community transmission.

In the updated guidelines, the CDC reiterated that COVID-19 vaccination is safe and recommended for everyone in the US aged 5 years and older. Those concerned about myocarditis should note the risk of Even as the more infectious Omicron variant causes breakthrough infections, the approved vaccines offer robust protection against severe COVID-19 disease, hospitalization, and death.

Individuals 5 and older who are immunocompromised should receive a 3-dose primary mRNA vaccine series, as opposed to the traditional 2. An additional “booster” dose is recommended for everyone 12 years and older, with the timing varying by vaccine type and immunocompetence.

The mRNA Moderna and Pfizer-BioNTech COVID-19 vaccines are recommended over Janssen for a primary and booster vaccine series, though the CDC emphasizes, “offering the Janssen COVID-19 Vaccine is preferable to not providing any COVID-19 vaccine.”