A Trial to Evaluate the Effect of CD388/MK1406 on the Immunogenicity of Fluzone® HD Vaccine (CD388.SQ.1.08/MK-1406-007)
A Phase 1, Double-blind, Randomized Trial to Evaluate Safety and Immunogenicity of Fluzone® High-Dose Influenza Vaccine When Concomitantly Administered With CD388, a Novel Long-Acting Antiviral Conjugate for the Prevention of Influenza
Who can join
Ages 18 to 49 · All sexes · Healthy volunteers welcome
Full eligibility criteria
Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Be ≥18 to ≤49 years of age * Be deemed healthy by the Investigator * Have not received any seasonal influenza vaccine and have not had a diagnosed or suspected influenza infection within 12 months prior to Day 1 of the trial Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Had an active malignancy within 5 years prior to screening, except basal cell or squamous cell skin cancer. Any history of breast cancer or melanoma is exclusionary. * Has previously been diagnosed with Guillain-Barre Syndrome following a previous influenza vaccination.
About the study
Approximately one billion cases of seasonal influenza occur annually. Of these, 3 to 5 million illnesses are severe and responsible for up to 650,000 deaths per year (WHO 2025). Yearly administration of an influenza vaccine for the prevention of influenza is currently recommended. However, the real-world vaccine effectiveness varied from 10% to 60% in the general population across the years of 2004 to 2024, with effectiveness in most years below 50% (CDC 2025) and decreasing to as low as 5% in immunocompromised individuals (Hughes 2021). Researchers are looking for other ways to prevent severe illness from the influenza virus.
The goals of this study are to learn if:
* MK-1406 (formerly CD388) is safe to take with Fluzone® * MK-1406 affects the immune response to Fluzone®
What is being tested
- Fluzone® High-Dose (HD) influenza vaccine (biological)
- MK-1406 Injection (combination product)
- Placebo (combination product)
Sponsor: Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) · Participants: 710 · Started: Nov 8, 2025
Contact the study team
- Toll Free Number · Phone: 1-888-577-8839
Official record on ClinicalTrials.gov — NCT07300085
Locations in the U.S.
| California | Parexel ( Site 0001), Glendale |
| Maryland | Parexel ( Site 0002), Baltimore |
Conditions
From ClinicalTrials.gov, data retrieved Nov 15, 2026. Each study sets its own eligibility; the study team decides who can join.