Third mRNA Vaccine Dose Ups Effectiveness Against Hospitalization

Receipt of a third COVID-19 mRNA vaccine dose is associated with increased vaccine effectiveness against COVID-19 hospitalization, according to research published in the Jan. 28 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Mark W. Tenforde, M.D., Ph.D., from the CDC COVID-19 Emergency Response Team, and colleagues examined the effectiveness of mRNA vaccines against COVID-19-associated hospitalization among 2,952 adults (1,385 COVID-19 case patients and 1,567 COVID-19-negative controls) hospitalized during Aug. 19 to Dec. 15, 2021. mRNA vaccine effectiveness was compared for adults eligible for but who had not received a third vaccine dose and vaccine-eligible adults who had received a third dose seven or more days before onset of illness (1,251 and 312 adults, respectively).

The researchers found that among 1,875 adults without immunocompromising conditions, vaccine effectiveness against COVID-19 hospitalization was higher among those who had received a booster dose than those who had received two doses (97 versus 82 percent). Findings were similar among the 1,077 adults with immunocompromising conditions who had received the third dose to complete the primary series versus recipients of two doses (88 versus 69 percent).

"Among adults with and without immunocompromising conditions who were eligible to receive a third dose of COVID-19 mRNA vaccine, third doses were found to increase protection beyond that of a two-dose vaccination series for the prevention of COVID-19 hospitalization," the authors write.