The Centers for Disease Control and Prevention (CDC) issued updated guidance Monday saying some immunocompromised people can get a fourth COVID-19 vaccine dose for additional protection.
The federal agency permits moderately and severely immunocompromised adults to get a fourth booster shot if they completed an initial series of an mRNA vaccine and received a third additional dose. The fourth shot can be administered six months after the most recent dose.
The adjusted recommendations come days after the CDC approved mix-and-match booster shots, where a person receives a different brand dose from their initial vaccination.
Under this guidance, moderately and severely immunocompromised people who got the Pfizer-BioNTech or Moderna vaccines for their first three shots can get a different booster shot if desired.
The CDC distinguished the definitions for additional dose and booster shot, saying an additional dose referred to a subsequent shot for people thought not to have an adequate immune response to the initial vaccine series.
Booster shots, on the other hand, refer to a subsequent dose given to those whose protection from the initial vaccine series is expected to have decreased over time.
The CDC officially advised immunocompromised people to get a third additional dose of an mRNA vaccine in August, so the earliest third dose recipients would not be eligible for a fourth shot until February. The additional third shot was recommended at least 28 days after the second dose.
Immunocompromised Johnson & Johnson recipients received different instructions to get a single COVID-19 booster shot at least two months after their initial dose, just like all adults who got the single-dose shot.
The federal agency granted the option for specific Moderna and Johnson & Johnson recipients to get booster shots last week following a unanimous advisory panel vote.
While all Johnson & Johnson-vaccinated adults are advised to get a booster, the CDC recommended the extra shot to certain vulnerable Moderna and Pfizer-BioNTech populations, including those aged 65 and older, those in long-term care facilities and those aged 50 to 64 with underlying medical conditions.
The CDC also granted the option of a booster dose following an mRNA vaccine to other adults with underlying medical conditions and adults at risk of contracting COVID-19 due to their occupational or institutional setting.
The Pfizer-BioNTech vaccine was authorized to be given to these populations last month, ahead of the Moderna and Johnson & Johnson booster approvals.