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Sustained Effectiveness of mRNA Vaccines Against COVID-19 Hospitalizations

  • MMWR
Aug 19, 2021 9:08 pm

The CDC has reported that mRNA vaccine effectiveness against COVID-19–associated hospitalizations was sustained over 24 weeks; but there is evidence of waning protection amongst the immunosuppressed.

They studied vaccine responses among 1,129 patients who received 2 doses of a mRNA vaccine, no decline in vaccine effectiveness against COVID-19 hospitalization was observed over 24 weeks. Vaccine effectiveness was 86% 2–12 weeks after vaccination and 84% at 13–24 weeks. Vaccine effectiveness was sustained among groups at risk for severe COVID-19.


This real-world study from 21 US hospitals included 3,089 mRNA vaccinated, hospitalized adults (including 1,194 COVID-19 case-patients and 1,895 non–COVID-19 control-patients); 21% of whom had an immunocompromising condition.

Vaccine effectiveness against COVID-19–associated hospitalization during the full surveillance period was:

  • Overall = 86%
  • Adults without immunocompromising conditions = 90%
  • Adults with immunocompromising conditions = 63% 

Effectiveness of mRNA vaccines against COVID-19–associated hospitalization was sustained over a 24-week period, including among groups at higher risk for severe COVID-19.


The author has no conflicts of interest to disclose related to this subject

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