US health officials have authorized a third dose of Covid-19 vaccines from Pfizer Inc and Moderna Inc for people with compromised immune systems, based on evidence that the two standard injections offered less robust protection in such populations.
Here’s what we know about who will be eligible for the additional vaccines:
The Food and Drug Administration updated the emergency use authorization granted to Pfizer injections, developed with German partner BioNTech, as well as Moderna’s vaccine to allow a third dose for people who have received organ transplants or those with a similarly weakened immune system.
Health officials have estimated that less than 3% of American adults would be candidates for a third dose.
The US Centers for Disease Control and Prevention said a third dose is recommended for people with moderate or severe immuno suppression.
They included people receiving treatment for solid tumor cancers and blood cancers, such as lymphoma or leukemia; patients who have undergone a bone marrow transplant in the last two years or are still taking medications to suppress their immune system; and patients with advanced or untreated HIV infection.
The CDC guidance includes people currently taking high-dose steroids and immune-suppressing biologic medications, including medications for Crohn’s disease, rheumatoid arthritis, and plaque psoriasis.