Cidara Therapeutics announced positive Phase IIb trial results for its long-acting antiviral biologic CD-388, demonstrating substantial prevention efficacy against seasonal influenza in healthy, unvaccinated adults aged 18-64. The trial met all primary and secondary endpoints with a single dose conferring protective effects lasting up to 28 weeks without dose-limiting adverse events. Shares of Cidara nearly doubled on the news. The company plans to engage with the FDA regarding Phase III trial design, aiming to provide an effective alternative to annual influenza vaccine shots, particularly benefiting high-risk populations. This progress positions CD-388 as a promising prophylactic in respiratory viral illnesses.