CDC Analyzes Bivalent mRNA Vaccine Efficacy Against COVID Variants

Using data estimates from national pharmacy testing, the CDC analyzed the preliminary efficacy of bivalent mRNA vaccines against multiple COVID variants. The data were collected from December 1, 2022, to January 13, 2023. According to the Morbidity and Mortality Weekly Report (MMWR) by the CDC, the XXB1.5 variant is becoming increasingly prevalent in the United States.

The report notes that the XXB1.5 variant has accounted for over 50% of cases in the northeast US as of December 31, 2022. However, until this point, researchers have had little insight into vaccine efficacy against XBB and XBB1.5.

The bivalent COVID boosters were approved in August 2022 for patients over 12. The vaccines began rollout in September, becoming available to the general public. However, since the initial launch of this preventative measure, the public has been confused about their utility, causing slower vaccine uptake.

According to an article published by the Kaiser Family Foundation in October 2022, nearly 40% of adults are unsure about recommendations regarding bivalent boosters. In fact, almost 20% of adults reported knowing ‘nothing at all’ about bivalent boosters. This confusion has likely contributed to slow vaccine uptake.

Considering the confusion, the CDC hoped to shed some light on the vaccine’s efficacy. The study notes that, for patients between 18 and 49, the bivalent COVID vaccine is 52% effective against symptomatic BA.5 infection. Concerning the XBB/XBB1.5 variants, the bivalent vaccine was roughly 48% effective.

The MMWR concludes, “As new SARS-CoV-2 variants emerge, continued vaccine effectiveness monitoring is important. All persons should stay up to date with recommended COVID-19 vaccines, including receiving a bivalent booster dose when eligible.”

The CDC and other healthcare organizations will monitor vaccine efficacy as patients continue to get vaccinated. Understanding vaccine efficacy may help inform the development of future boosters. As the pandemic continues to evolve, constant monitoring of infection rates, vaccination rates, and efficacy rates will be critical to public health.