HealthDay News — Vaccine effectiveness (VE) of two doses of mRNA COVID-19 vaccine against COVID-19-associated hospitalization is lower among immunocompromised adults, according to research published in the Nov. 2 early-release issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Peter J. Embi, M.D., from the Regenstrief Institute in Indianapolis, and colleagues examined VE among immunocompromised adults using data from the VISION Network for hospitalizations among people aged 18 years or older with COVID-19-like illness from 187 hospitals in nine states during Jan. 17 to Sept. 5, 2021. VE against COVID-19-associated hospitalization conferred by completing a two-dose series of mRNA COVID-19 vaccine was assessed by comparing 20,101 immunocompromised adults (53 percent fully vaccinated) and 69,116 immunocompetent adults (43 percent fully vaccinated).

The researchers found that among immunocompromised patients, the VE of two doses of mRNA COVID-19 vaccine against COVID-19-associated hospitalization was lower than that among immunocompetent patients (77 versus 90 percent). This difference persisted regardless of vaccine type, age group, and timing of hospitalization relative to predominance of the severe acute respiratory syndrome coronavirus 2 delta variant in the state of hospitalization. Across immunocompromising condition subgroups, VE varied from 59 percent (organ or stem cell transplant recipients) to 81 percent (rheumatologic or inflammatory disorder).


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“Immunocompromised patients were significantly less protected from severe COVID-19 outcomes compared with immunocompetent patients, supporting the recommendation for administration of a third dose of mRNA vaccine to further enhance protection of moderately to severely immunocompromised persons against severe COVID-19 outcomes,” the authors write.

Several authors disclosed financial ties to the pharmaceutical industry, including to companies involved in COVID-19 vaccine trials.

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