NCT04639466

A Synthetic MVA-based SARS-CoV-2 Vaccine, GEO-CM04S1, for the Prevention of COVID-19 Infection

Completed Phase 1, PHASE2 Last updated 10 February 2026

What this trial tests

Phase 1, PHASE2 trial testing Placebo Administration in COVID-19 Infection in 119 participants. Completed in 3 December 2025.

Timeline

19 November 2020

Primary endpoint
31 October 2025

3 December 2025

Quick facts

Lead sponsor	GeoVax, Inc.
Phase	Phase 1, PHASE2
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	double
Primary purpose	treatment
Enrollment	119
Start date	19 November 2020
Primary completion	31 October 2025
Estimated completion	3 December 2025
Sites	3 locations across United States

Drugs / interventions tested

• Placebo Administration — full drug profile →
• Synthetic MVA-based SARS-CoV-2 Vaccine COH04S1 — full drug profile →

Conditions studied

• COVID-19 Infection — all drugs for COVID-19 Infection →

Sponsor

GeoVax, Inc. — full company profile →

Who can join

Adults 18 to 55, any sex, with COVID-19 Infection. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

This phase I trial evaluates the side effects and best dose of GEO-CM04S1 (previously designated as COH04S1), a synthetic modified vaccinia Ankara (MVA)-based SARS-CoV-2 vaccine, for the prevention of COVID-19 infection. COVID-19 infection is caused by the SARS-CoV-2 virus. SARS-CoV-2 has demonstrated the capability to spread rapidly, leading to significant impacts on healthcare systems and causing societal disruption. GEO-CM04S1 was created by placing small pieces of SARS-CoV-2 DNA (the chemical form of genes) into synthetic MVA, which may be able to induce immunity (the ability to recognize and fight against an infection) to SARS-CoV-2. The purpose of the Phase 1 study is to determine the safety and the optimal dose of the GEO-CM04S1 vaccine.

The Phase 2 study is designed as a multi-center, double-blind, randomized, parallel, study to evaluate the safety profile of 2 dose levels of GEO-CM04S1 as a single booster shot to assess the immune response measured by the fold-increase in antibody against SARS-CoV-2 Spike protein at day 28 post-injection among healthy adult volunteers.

Publications & conference data

8 peer-reviewed publications reference this trial (live from Europe PMC):

1. COVID-19 vaccines: rapid development, implications, challenges and future prospects.
   Kashte S, Gulbake A, El-Amin Iii SF, Gupta A. · · 2021 · cited 240× · PMID 33677814 · DOI 10.1007/s13577-021-00512-4
2. Efficacy and safety of COVID-19 vaccines.
   Graña C, Ghosn L, Evrenoglou T, Jarde A, et al · · 2022 · cited 227× · PMID 36473651 · DOI 10.1002/14651858.cd015477
3. COVID-19 Vaccines: A Review of the Safety and Efficacy of Current Clinical Trials.
   Yan ZP, Yang M, Lai CL. · · 2021 · cited 89× · PMID 33923054 · DOI 10.3390/ph14050406
4. Advances in gene-based vaccine platforms to address the COVID-19 pandemic.
   Pushparajah D, Jimenez S, Wong S, Alattas H, et al · · 2021 · cited 66× · PMID 33422546 · DOI 10.1016/j.addr.2021.01.003
5. Synthetic multiantigen MVA vaccine COH04S1 protects against SARS-CoV-2 in Syrian hamsters and non-human primates.
   Chiuppesi F, Nguyen VH, Park Y, Contreras H, et al · · 2022 · cited 50× · PMID 35064109 · DOI 10.1038/s41541-022-00436-6
6. Safety and immunogenicity of a synthetic multiantigen modified vaccinia virus Ankara-based COVID-19 vaccine (COH04S1): an open-label and randomised, phase 1 trial.
   Chiuppesi F, Zaia JA, Frankel PH, Stan R, et al · · 2022 · cited 43× · PMID 35287430 · DOI 10.1016/s2666-5247(22)00027-1
7. Replicating Viral Vector-Based Vaccines for COVID-19: Potential Avenue in Vaccination Arena.
   Chavda VP, Bezbaruah R, Athalye M, Parikh PK, et al · · 2022 · cited 40× · PMID 35458489 · DOI 10.3390/v14040759
8. A Narrative Review of COVID-19 Vaccines.
   Eroglu B, Nuwarda RF, Ramzan I, Kayser V. · · 2021 · cited 38× · PMID 35062723 · DOI 10.3390/vaccines10010062