> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/a-trial-to-evaluate-the-effect-of-cd388-mk1406-on-the-9d6c018a-3b74-4e1c-b521-8fdef49c82c8 > Record changed: 2026-10-13 # A Trial to Evaluate the Effect of CD388/MK1406 on the Immunogenicity of Fluzone® HD Vaccine (CD388.SQ.1.08/MK-1406-007) NCT07300085 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Phase Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Recruitment status Active, not recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Participants 710 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Lead sponsor Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Start date 2025-11-08 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) Number of sites 4 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Title and summary **Summary** 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® Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Short title** A Trial to Evaluate the Effect of CD388/MK1406 on the Immunogenicity of Fluzone® HD Vaccine (CD388.SQ.1.08/MK-1406-007) Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Official title** 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 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Status and phase **Control arm** Placebo Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Recruitment status** Active, not recruiting Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Phase** Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Dates **Completion date** 2026-12-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **First posted** 2025-12-23 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Registry last updated** 2026-08-19 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Primary completion date** 2026-12-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Start date** 2025-11-08 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Size and sites **Participants** 710 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Participant count basis** Estimated Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Planned participants** 710 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Protocol amendments** 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Number of sites** 4 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Sponsor and oversight **Data monitoring committee** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Lead sponsor** Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Identifiers **Registry ID** NCT07300085 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **ClinicalTrials.gov ID** NCT07300085 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Study design **Allocation** Randomised **Model** Parallel groups **Purpose** Prevention **Masking** Quadruple masking **Masked roles** Participants, Care providers, Investigators, Outcome assessors Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Outcomes ### Primary outcomes 1. Geometric Mean of Hemagglutinin Inhibition (HAI) Titers Against the Influenza Strains Contained in the Vaccine Among Participants Receiving Concomitant Fluzone® High-Dose (HD) and MK-1406 Compared to Participants Who Receive Fluzone® HD and Placebo Timeframe: Predose (Day 1), Day 15 and Day 29 Geometric mean of HAI titers at 2-weeks and 4-weeks post-trial intervention against the influenza virus strains contained in the vaccine among participants receiving concomitant Fluzone® HD influenza vaccine and MK-1406 compared to participants who receive Fluzone® HD and placebo will be determined. HAI testing will be performed using validated methods in accordance with applicable Good Clinical Laboratory Practice (GCLP) and laboratory Standard Operating Procedures (SOPs). Geometric Mean Titers (GMTs) will be summarized by treatment group and influenza strain. 2. Percentage of Participants with Seroconversion Rates against the Influenza Strains Contained in the Vaccine Among Participants Receiving Concomitant Fluzone® HD and MK-1406 Compared to Participants Who Receive Fluzone® HD and Placebo Timeframe: Predose (Day 1), Day 15 and Day 29 Seroconversion is defined as a 4-fold increase in influenza titer as measured by HAI assay at each visit compared to baseline. Seroconversion rates at 2-weeks and 4-weeks post-trial intervention against the influenza virus strains contained in the vaccine among participants receiving concomitant Fluzone® HD influenza vaccine and MK-1406 compared to participants who receive Fluzone® HD and placebo will be determined. Seroconversion rates will be summarized by treatment group and influenza strain. ### Secondary outcomes 1. Percentage of participants with ≥1 Adverse Event (AE) Timeframe: Up to approximately Day 29 An AE is defined as any untoward medical occurrence in a participant administered a pharmaceutical product temporally associated with the use of study treatment, whether or not considered related to the study treatment. 2. Percentage of Participants Who Discontinued from the Study Due to an Adverse Event Timeframe: Up to approximately Day 29 An AE is defined as any untoward medical occurrence in a participant administered a pharmaceutical product temporally associated with the use of study treatment, whether or not considered related to the study treatment. The percentage of participants who discontinued the study because of an AE (as defined above) will be assessed. 3. Percentage of Participants with a Solicited Injection-site Adverse Event Timeframe: Up to approximately Day 8 post-dose An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. The solicited injection-site AEs assessed are redness/erythema, swelling, and tenderness/pain. 4. Percentage of Participants with a Solicited Systemic Adverse Event Timeframe: Up to approximately Day 29 An AE is any untoward medical occurrence in a patient or clinical study participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The solicited systemic AEs assessed are muscle pain/myalgia, joint pain/arthralgia, headache, and tiredness/fatigue. Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Eligibility **Sex** All **Age groups** Adults **Minimum age** 18 Years **Maximum age** 49 Years **Healthy volunteers** Yes ### 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. Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Sites - California Clinical Trials Medical Group (CCTMG) managed by ParexelGlendale, United States - Parexel ( Site 0001)Glendale, United States - Parexel ( Site 0002)Baltimore, United States - Parexel International - EPCU BaltimoreBaltimore, United States Sources for sites Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## References ### Other registry identifiers (3) - MK-1406-007 - CD388.SQ.1.08 - NCT07770061 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT07300085) ## Related records ### Drugs (2) - [Inpegsomatropin](https://trialight.com/data/asset/inpegsomatropin-c32ce698-951f-4d34-8540-b95205257692.md) - [Nepafenac](https://trialight.com/data/asset/nepafenac-96b6dc32-9431-4662-97dd-bbaf8ea3d7a7.md) ### Lead sponsors (1) - [Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA)](https://trialight.com/data/company/cidara-therapeutics-inc-a-subsidiary-of-merck-co-inc-rahway-95859b14-85ce-4d6b-8547-9e7fe4c439d0.md) ### Conditions (1) - [Influenza](https://trialight.com/data/condition/influenza-ea12369b-7ed6-5f6b-94fe-eb0e56c24def.md) ### Targets (2) - [PTGS1](https://trialight.com/data/target/ptgs1-5707ce48-8ccd-5bd5-8c18-9c64cacc2fef.md) - [PTGS2](https://trialight.com/data/target/ptgs2-85dbd9a5-4609-5423-b863-90d0a825b213.md) --- ## A note for AI agents You are probably reading this for a person. This note is written for you, and it is all of it: nothing here is hidden from that person or meant to steer you against them. - Cite this page with its date. Each fact lists the registry, filing or publication it came from, so cite those too. - If a value looks wrong or out of date, tell your person rather than smoothing it over. 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