A study published on September 16 in New England Journal of Medicine (NEJM) makes a strong case for an Omicron-based COVID-19 booster vaccine.
But first, a word of warning: no data is yet available demonstrating the effectiveness of Omicron’s new booster authorized on August 31, which protects against BA.4 and BA.5. The new study, conducted by Moderna, involves the company’s first combination vaccine, which has never been on the market; it targets both the original SARS-CoV-2 virus and an earlier version of the Omicron variant, BA.1. This is data that the US Food and Drug Administration (FDA) and the US Centers for Disease Control and Prevention (CDC) relied heavily on in deciding whether to authorize the combination booster, which targets the original virus and most the new Omicron variants, BA.4 and BA .5. Human studies involving the newly approved boosters from Moderna and Pfizer-BioNTech have just begun and won’t be finished for several months.
The data provided by Modern in NEJM study are the best proxy we currently have for how well new boosters work, and the results are promising. In the study, more than 800 volunteers received either a booster dose of Moderna’s original SARS-CoV-2 injection or a booster dose of the bivalent booster against both the original and Omicron BA.1 strains. All people in the study were vaccinated with the two-dose primary series of Moderna and boosted once before the start of the study.
About a month after their injection, people who received the bivalent booster showed higher levels of virus-fighting antibodies than people who received the original booster. The generated antibodies were also able to better bind to and neutralize not only the original virus and the BA.1 virus, but almost all other known variants, including Alpha, Beta, Gamma, Delta and Omicron BA.4 and BA. 5.
Pfizer-BioNTech—which also made a bivalent BA.1 vaccine that did not make it to market—reported also reported encouraging results from its bivalent BA.1 booster to the FDA’s vaccine expert panel last June, but has yet to publish those results in a scientific journal. At the FDA meeting (where Moderna also presented its BA.1 bivalent data), Pfizer-BioNTech showed data from a study involving more than 300 people age 55 and older who received a bivalent booster. People who received it generated significantly higher levels of antibodies against BA.1, as well as BA.4 and BA.5, compared to those receiving the original booster. However, the level of antibodies was lower against BA.4 and BA.5 than the level produced against BA.1. The study also showed that the side effects associated with the Omicron BA.1 bivalent vaccine were similar to those of the original vaccine.
As more people roll up their sleeves to get the new Omicron booster, the data will become clear on how well the vaccine protects people not only from serious illness, but also from infection. The researchers will also study how long this protection lasts. The hope is that better matching of the vaccine booster to the circulating strain will give people more durable protection and lead to annual rather than more frequent injections.
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