A New Era in Flu Prevention? — CD388 Shows One-Shot Seasonal Protection

Introduction

Flu prevention has long relied on seasonal vaccines, but a new innovation may challenge that paradigm. CD388, a long-acting antiviral developed by Cidara Therapeutics, has shown the potential to protect people through an entire flu season with a single injection.

Clinical Trial Results

A phase 2 trial in the U.S. and U.K. enrolled 5000 healthy adults who had not received a flu vaccine. Among them, the highest dose of CD388 demonstrated 76.1% efficacy. The medium and low doses showed 61.3% and 57.7% efficacy, respectively, all statistically significant, with no serious side effects observed.

Mechanism of Action

CD388 is a modified version of zanamivir (Relenza), originally launched by GSK in 1999. It inhibits neuraminidase (NA), a key viral enzyme, by chemically attaching the drug to an Fc antibody fragment to extend its durability in the body.

Comparison with Traditional Vaccines

Conventional vaccines often achieve only ~40% efficacy due to mismatch with circulating strains. CD388 targets a conserved region of NA, potentially offering broader protection. Its one-time injection format also offers strong advantages in compliance and convenience.

Challenges and Future Outlook

While safety appears promising, resistance to NA inhibitors must be monitored. Cost and mass production capacity remain key issues. A larger trial is planned in early 2026 in the Southern Hemisphere, including vaccine co-administration for high-risk populations.

Author’s Perspective

CD388 could reshape flu prevention strategies as a non-vaccine option, particularly for vulnerable groups. If manufacturing and pricing are addressed effectively, this one-shot approach could redefine seasonal protection standards.

Reference: Science July 3