The stack of derivative actions against Moderna is growing in the District of Massachusetts, with the latest case challenging representations of the company's RSV vaccine's success filed on Nov. 12.

The case is the fifth to bring similar allegations against Moderna in the same court, with three others, all filed Nov. 5, surfaced by Law.com Radar.

Another was filed Oct. 28.

The Rosen Law Firm is representing plaintiffs in all five cases, with Bragar Eagel & Squire appearing alongside the firm in the most recently filed.

Rigrodsky Law and Grabar Law Offices are counsel in another, and Robbins LLP and Wolf Haldenstein Adler Freeman & Herz entered appearances in one case each.

The newest case has not been assigned to a judge, while U.S. District Judge Indira Talwani is overseeing the four earlier suits.

The litigation involves the development of mRESVIA, Moderna's vaccine aimed at protecting older adults from respiratory syncytial virus (RSV). Attorneys for the shareholder plaintiffs did not respond for comment.

In January 2023, Moderna, a Delaware corporation headquartered in Massachusetts, announced clinical trials showed mRESVIA was 83.7% effective against RSV-related lower respiratory tract disease.

In May of this year, Moderna announced a 78.7% efficacy rate, which was followed by a 5.9% drop in Moderna's stock price.

In June, the complaint stated, stock prices dipped another 11% after a presentation to a Centers for Disease Control and Prevention committee indicated mRESVIA was between 49.9% and 50.3% effective, "significantly lower than competing vaccines."

The complaint, which names eight causes of action, claims Moderna leadership failed to tell investors mRESVIA was less effective than originally represented.

It claimed the company breached its fiduciary duties by overstating prospects for the vaccine's clinical and commercial success between Jan. 18, 2023, the day after Moderna announced the results of a clinical trial, and June 25, 2024, the day before the presentation to the CDC committee.

It also alleges that as the result of Moderna's stock being artificially inflated, multiple board members who knew of the discrepancy profited from insider trading and Moderna overpaid $166.3 million for stock buybacks.

A spokesperson for Moderna did not immediately respond for comment.