Dive Insight:

Although omicron appears to cause hospitalizations and deaths at lower rates than earlier variants, the large number of cases in the U.S. means the variant’s spread is straining hospitals, as well as the doctors, nurses and other healthcare professionals that staff them.

Omicron contains a high number of mutations in the coronavirus’ characteristic spike protein, which make it harder for antibodies trained against the original strain to latch onto it. As a result, antibody drugs from Eli Lilly and Regeneron have proved less able to neutralize omicron in laboratory testing, while “breakthrough” infections have become more common among vaccinated individuals.

New data from Moderna, published Wednesday in The New England Journal of Medicine, give a better sense of this problem, showing protection from its current vaccine to be enduring, albeit more weakly versus omicron. The company’s analysis found that, among people given two doses, 55% were still able to neutralize omicron seven months later. Booster doses increased neutralizing antibody levels and, six months later, all participants had detectable immune responses versus omicron.

But weakened protection versus infection, particularly from a two-dose series, has motivated both Moderna and the team of Pfizer and BioNTech to design new boosters with omicron in mind.

Moderna’s booster study will enroll people 18 years of age or older who either received their second shot at least six months ago and are unboosted, or who received a booster shot at least three months previously.

The design differs from Pfizer and BioNTech’s trial of an omicron booster as Moderna won’t test a fourth shot of its original vaccine. By testing a fourth dose, Pfizer and BioNTech could give researchers, drugmakers and regulators important information as to whether variant-specific shots are needed, particularly as current vaccines retain some efficacy and as a mutating virus births new variants.

Moderna did not respond to questions from BioPharma Dive regarding the study’s design.

It’s not fully clear how the Food and Drug Administration would review an omicron booster, but officials have indicated they could move more quickly than in their review of the original shots.

Moderna didn’t say when it expects results from the variant-specific trial. Pfizer CEO Albert Bourla has previously said its shot could be ready in March.