The U.S. Centers for Disease Control and Prevention (CDC) have discovered that some immunocompromised residents in the United States may be required to get a fourth dose of the mRNA COVID-19 vaccines. While the CDC didn’t announce an official recommendation, the agency updated its COVID-19 vaccine policy guidelines on October 25 to indicate that people who are moderately or severely immunocompromised or have certain underlying medical conditions may need to get additional protection from COVID-19. This newly updated guidance won’t apply to people with healthy immune systems. 

This new announcement comes just two months after the CDC approved booster shots, or third doses, of the mRNA vaccines for adults with compromised immune systems. Similar to the third booster shot, immunocompromised adults can get a 4th dose of the Moderna or Pfizer-BioNTech vaccines roughly 6 months after they have acquired their third dose (via Axios). The CDC says the extra dose may be a requirement for people with underlying conditions who didn’t have a robust immune response after receiving the first 2 doses of the mRNA vaccines.

Who is eligible for a fourth shot?

According to a study from Johns Hopkins University, fully-vaccinated people with compromised immune systems are almost 500 times more likely than most vaccinated people to be hospitalized with COVID-19 or die from the virus (via CNN). Other smaller studies also show that vaccinated immunocompromised people account for 44% of all breakthrough COVID-19 cases that lead to hospitalization. Fortunately, booster shots have been proven to increase the antibody response in many immunocompromised adults — so who exactly is eligible for a fourth shot of the vaccine?

The CDC reported that people with certain conditions, like cancer and advanced or untreated human immunodeficiency virus (HIV), organ transplant and stem cell recipients, and people who dose on immunosuppressants all qualify for a 4th dose. Close to 9 million people, or 2% of the U.S. population, fall under these qualifications. Since this new guidance isn’t an official recommendation, however, anyone who falls into this category should consult with their doctors before getting a fourth booster shot to discuss whether or not an additional dose is actually necessary.

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