New antiviral shot could boost flu protection when given with vaccine

NCT ID NCT07300085

Ongoing Prevention Sponsor: Cidara Therapeutics Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA) Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This early-stage trial is testing whether a new long-acting antiviral medicine called CD388 can be safely given at the same time as the high-dose flu vaccine. About 100 healthy adults aged 18 to 49 will receive either the vaccine plus CD388 or the vaccine plus a placebo. Researchers will check if CD388 interferes with the body's immune response to the vaccine and monitor for any side effects.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Fluzone High-Dose influenza vaccine and CD388 (a long-acting antiviral)
What this could lead to: If successful, this could show that combining a long-acting antiviral with the flu vaccine is safe and doesn't reduce vaccine effectiveness, potentially offering better flu prevention.
What could go wrong: This is a very early (phase 1) and small trial (100 healthy adults), so results may not apply to older or sicker people. The main goal is safety and immune response, not proof of preventing flu.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

influenza prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

HEALTHY PARTICIPANTS

Contacts and locations

Locations

California Clinical Trials Medical Group (CCTMG) managed by Parexel

Glendale, California, 91206, United States
Parexel International - EPCU Baltimore

Baltimore, Maryland, 21225, United States

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