Moderna RSV Vaccine Less Effective Than Claimed, Lawsuit Says

Moderna Inc. misled investors about the effectiveness of its RSV vaccine candidate, causing a stock drop when the disappointing results were revealed, according to a proposed securities class action.

The July 2023 biologics license application that Moderna submitted to the US Food and Drug Administration for its vaccine candidate—called mRESVIA or mRNA-1345—indicated an 84% efficacy rate, investor Mason Wentz says. He filed his complaint Aug. 9 in the US District Court for the District of Massachusetts.

But its efficacy against respiratory syncytial virus, as announced at the time of the FDA’s approval of the vaccine on May 31, 2024, was ...