Moderna hopes to offer updated COVID-19 boosters in the fall that combine its original vaccine with protection against the omicron variant. On Tuesday, it reported a preliminary hint that such an approach might work.

Today’s COVID-19 vaccines all are based on the original version of the coronavirus. But the virus continues to mutate, with the super-contagious omicron variant — and its siblings — the latest threat.

Before omicron came along, Moderna was studying a combination shot that added protection against an earlier variant named beta. Tuesday, the company said people given that beta-original vaccine combination produced more antibodies capable of fighting several variants — including omicron — than today’s regular booster triggers.

While the antibody increase was modest, Moderna’s goal is to produce a combination shot that specifically targets omicron. “These results really give us hope” that next step will work even better, said Dr. Jacqueline Miller, a Moderna vice president.

Tuesday’s data was reported online and hasn’t been vetted by independent experts.

COVID-19 vaccines still are providing strong protection against severe disease, hospitalization and death, even against omicron. That variant is so different from the original coronavirus that it more easily slips past the immune system’s defenses, although studies in the U.S. and elsewhere show an original booster dose strengthens protection