In the Journals: Do Bivalent COVID-19 Vaccines Improve Protection?

At the end of October 2022, about two months after the first CDC recommendation, Qian Wang and co-workers in David Ho’s laboratory at Columbia published the first data evaluating the relative immunogenicity of a bivalent booster dose (N=21) versus a monovalent booster dose (N=19) (Wang Q, Bowen A, Valdez R, et al. Antibody responses to omicron BA.4/BA.5 bivalent mRNA vaccine booster shot. 2022, Oct. 24. bioRxiv, https://doi.org/10.1101/2022.10.22.513349.) Sera were obtained about 25 days after the booster dose. The group receiving the bivalent booster were significantly younger (average 36 years of age) than the group receiving the monovalent vaccine (average 55 years of age). One would expect that the younger age group recipients would have a greater immune response simply based on the robustness of their younger immune systems. Nonetheless, there was no difference in neutralizing antibody titers against BA.4/BA.5 in those who had received the bivalent vaccine as compared with those who had received the monovalent vaccine.

The authors concluded, “Boosting with a new bivalent mRNA vaccine targeting both BA.4/BA.5 and an ancestral SARS-CoV-2 strain did not elicit discernibly superior virus-neutralizing antibody responses compared with boosting with an original monovalent vaccine. These findings may be indicative of immunological imprinting, although follow-up studies are needed to determine if the antibody responses will deviate in time, including the impact of a second bivalent booster.”

As suggested by these findings, it is unlikely that the bivalent booster dose will offer significantly greater protection against the omicron subvariants than the previously available monovalent vaccines.