Altimmune Inc

On May 6, 2024, a class action complaint was filed in federal district court in the District of Maryland, Southern Division, naming as defendants, the Company and three of the Company’s current executive officers, captionedMogan v. Altimmune, Inc.,* et al.,* No. 24-cv-01315 (D. Md.). The complaint alleges that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 thereunder, by making false and misleading statements and omissions of material fact to the investing public including the plaintiff and class members, who purchased or otherwise acquired the Company’s common stock between December 1, 2023 and April 26, 2024. The plaintiff and class members seek to have the action maintained as a class action under Rule 23 of the Federal Rules of Civil Procedure

and for the defendants to pay damages, interest, and an award of costs, including attorneys’ fees. The Company intends to vigorously defend against the lawsuit.

From time to time, we may be involved in various legal proceedings or investigations, which could be costly and impose a significant burden on management and employees. The results of any current or future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on us because of defense and settlement costs, diversion of management resources, and other factors.