Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States

The CDC has updated the Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States to indicate that the second dose of mRNA COVID-19 vaccines may be given up to 8 weeks after the first dose.  

The rationale for this change is that "Some studies in adolescents (ages 12-17 years) and 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." They also say that "an 8-week interval may be optimal for some people ages 12 years and older, especially for males ages 12 to 39 years."

 A 3-week interval for Pfizer and a 4-week interval for Moderna continue to be recommended for people who are moderately to severely immunocompromised, adults ages 65 years and older, and others who need rapid protection due to increased concern about community transmission or risk of severe disease.