Exhibit 99.1 Altimmune Announces Positive Lean Mass Preservation Data for Pemvidutide and Reports Fourth Quarter and Full Year 2023 Financial Results Body composition study showed lean mass preservation, with only 25.5% of weight loss derived from lean mass Enrollment ongoing in IMPACT Phase 2b trial of pemvidutide in Metabolic Dysfunction-Associated Steatohepatitis (MASH), with topline 24-week data expected Q1 2025 Preclinical study results showed a direct anti-fibrotic effect of pemvidutide in a non-steat ...