The shot targeting both Omicron and the original virus strain produced a strong immune response against subvariants BA.4 and BA.5, the company said

If you’ve had Covid before, why can you get it again? WSJ’s Daniela Hernandez explains what the possibility of reinfections means for the future of public-health policy and the Covid-19 pandemic. Illustration: David Fang

Moderna Inc. said a modified version of its Covid-19 vaccine induced potent immune responses against fast-spreading Omicron subvariants among volunteers in a new study.

One month after receiving the company’s tweaked shot, study subjects’ neutralizing antibodies against Omicron subvariants BA.4 and BA.5 increased significantly, regardless of whether they were previously infected, Moderna said Wednesday.

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