A New Booster to Fight COVID-19

Volume 20, Issue 2

Two years into the pandemic, and the fight against COVID-19 wages on. Many public health experts are predicting a winter surge, one that will be entirely driven the Omicron variant.

Previous versions of the COVID-19 vaccines were developed prior to the beginning of the Omicron era, which is salient given that this version of the virus has specific immune-evading mutations in the spike protein. A recently developed bivalent COVID-19 booster dose was released to the US population in September, and this new booster is said to offer targeted protection against this variant.

In this week’s issue of Talking Therapeutics, we explore some of the published data regarding the effectiveness of this new booster compared to the prior versions of the vaccine.

In a new paper, the authors compared 50 μg of the new bivalent vaccine (25 μg each of ancestral Wuhan-Hu-1 and Omicron BA.1 spike messenger RNAs) with the previously authorized 50-μg booster. The vaccines were given as a second booster in adults who had previously received a 2-dose (100-μg) primary series and first booster (50-μg) at least 3 months earlier. Of note, this was not a clinical study; rather, it was designed to test the antigenicity of this new booster against the old.

Overall, this study had several interesting findings:

• In participants with no previous COVID-19 infection, the geometric mean titers of neutralizing antibodies against the Omicron BA.1 variant were 2372.4 (95% confidence interval [CI], 2070.6 to 2718.2) after receipt of the mRNA-1273.214 booster and 1473.5 (95% CI, 1270.8 to 1708.4) after receipt of the mRNA-1273 booster.
• The new bivalent booster was effective against Omicron BA.4 and BA.5 (BA.4/5), and the new booster also elicited higher binding antibody responses against multiple other variants (alpha, beta, gamma, and delta) as compared to the old booster.

These data were not intended to provide insight into the clinical effectiveness of this new booster to prevent infection or severe disease related to COVID-19 infection. As such, we need to wait for additional clinical data to fully evaluate the safety and efficacy profile of this new booster.

Nonetheless, the preliminary data seem very promising.