Immunocompromised people may get less protection from mRNA vaccines: CDC

A Centers for Disease Control and Prevention (CDC) study suggested that immunocompromised people may get “significantly less” protection from the two mRNA COVID-19 vaccines, supporting the push for additional doses among the vulnerable population. 

The research released Tuesday calculated mRNA vaccine effectiveness against COVID-19 hospitalizations among immunocompromised adults at 77 percent, while “immunocompetent” adults reached 90 percent effectiveness. 

Despite the lower vaccine effectiveness, both the Moderna and Pfizer-BioNTech vaccines provided protection to immunocompromised people against COVID-19-related hospitalizations, the CDC said. 

The study encompassed data from about 89,000 adult admissions in 187 hospitals across nine states between Jan. 17 and Sept. 5, including approximately 20,000 immunocompromised patients and almost 70,000 immunocompetent patients. 

A slight majority, 53 percent, of immunocompromised adults were fully vaccinated, compared to 43 percent of other adults. 

The drop in vaccine effectiveness among immunocompromised patients remained despite the type of mRNA vaccine used, age group and whether the delta variant was dominant at the time of hospitalization.

The effectiveness of the vaccine differed depending on the immunocompromising condition, ranging from 59 percent among organ or stem cell transplant recipients to 81 percent among those with a rheumatologic or inflammatory disorder.

Patients who got partially vaccinated, at least three doses or the Johnson & Johnson vaccine were excluded from the research.

The study backs the CDC recommendations for immunocompromised people who initially received one of the mRNA vaccines to get a third additional dose followed by a booster dose of any shot.  

The agency authorized booster shots for certain populations of mRNA vaccine recipients, including the immunocompromised, in recent weeks after approving a third additional dose in August. 

The CDC defines immunocompromised people as those with suppressed immune systems due to health conditions or medications. About 3 percent of the adult population is immunocompromised.