HealthDay News — A bivalent booster mRNA vaccine dose is effective against COVID-19-associated hospitalization in adults and seniors, according to 2 studies published in the December 16 early-release issue of the US Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Mark W. Tenforde, MD, PhD, from the CDC in Atlanta, and colleagues examined vaccine effectiveness (VE) of a bivalent mRNA booster dose (after 2, 3, or 4 monovalent doses) compared with no previous vaccination or previous receipt of two, three, or four monovalent-only mRNA vaccine doses among immunocompetent adults aged 18 years or older. The researchers found that the VE of a bivalent booster dose against COVID-19-associated emergency department/urgent care encounters was 56% compared with no vaccination and 31 and 50%, respectively, compared with monovalent vaccination only with the last dose 2 to 4 or 11 months or more earlier. VE against COVID-19 associated hospitalizations was 57% compared with no vaccination and was 38 and 45%, respectively, compared with monovalent vaccination only with the last dose 5 to 7 and 11 months or more earlier, respectively.

Diya Surie, MD, also from the CDC, and colleagues examined the effectiveness of a bivalent booster dose received after two or more doses of monovalent mRNA vaccine against COVID-19-associated hospitalizations among immunocompetent older adults (65 years or greater). The researchers found that the VE of a bivalent booster dose received seven or more days before illness onset against COVID-19-associated hospitalization was 84% compared with unvaccinated persons. The relative VE of a bivalent booster vaccine dose was 73% compared with persons who received two or more monovalent-only mRNA vaccine doses.

“All eligible persons, especially adults aged ≥65 years, should receive a bivalent booster dose to maximize protection against COVID-19 hospitalization this winter season,” Surie and colleagues write.

Several authors from both studies disclosed financial ties to the pharmaceutical industry.

Abstract/Full Text – Tenforde

Abstract/Full Text – Surie