A Phase 1/2A, Randomized Study of a T Follicular Helper (TFH)-Targeting Genetic Vaccine Strategy Designed to Induce Broad, Durable Immune Responses

The goal of this clinical trial is to test two investigational COVID-19 booster vaccines, called CoTend-s3BXBB and CoTend-BXBB, in healthy volunteers ages 40-64. The CoTend-s3BXBB vaccine includes a component called "s3", which was designed to improve the body's response to the vaccine. CoTend-BXBB is the same vaccine without s3. The main questions the study aims to answer are: 1) Is the investigational vaccine safe? 2) Does "s3" lead to bigger, broader, and longer-lasting responses to the vaccine? 5 different doses of the vaccines will be studied. Participants will receive a single dose of either CoTend-s3BXBB, CoTend-BXBB, or placebo. Participants will be monitored for side effects. Saliva, nasal, and blood samples will be collected and immune responses to the vaccine will be measured.

NCT Number	NCT06810934
Lead Sponsor	Kara Chew Collaborators: University of California, San Francisco, University of California, Davis, Tendel Therapies, Inc., National Institute of Allergy and Infectious Diseases (NIAID)
Conditions	COVID-19, SARS-CoV-2 Infection
Enrollment	80 participants
Start Date	2025-10-21
Primary Completion	2027-12 (estimated)
Study Completion	2029-10 (estimated)
Updated on ClinicalTrials.gov	2025-10-31