Immunogenicity of BA.5 Bivalent mRNA Vaccine Boosters

To the Editor: Waning immunity after messenger RNA (mRNA) vaccination and the emergence of variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have led to reduced mRNA vaccine efficacy against symptomatic infection and severe disease. 1,2 Bivalent mRNA boosters (manufactured by Pfizer-BioNTech and Moderna) expressing the spike protein of the B.1.1.529 (omicron) BA.5 sublineage and the ancestral WA1/2020 strain have been developed because BA.5 substantially evades neutralizing antibodies. 3 However, the immunogenicity of the BA.5-containing bivalent mRNA boosters remains unknown.

• RI
  Ragon Institute of MGH, MIT and Harvard
• MF
  Musk Foundation
• MC
  Massachusetts Consortium on Pathogen Readiness
• NC
  National Cancer Institute

  Award: CA260476
• NI
  National Institute of Allergy and Infectious Diseases

  Award: AI69309