Study on Immunogenicity, Reactogenicity and Safety of the VACΔ6 Vaccine in Volunteers Aged 18-60 Years

Smallpox Clinical Trial

Official title: Double-blind, Comparative, Randomized, Placebo-controlled Study on Immunogenicity, Reactogenicity and Safety of Live Cell-based Vaccine Against Smallpox and Other Orthopoxvirus Infections (VACΔ6 Vaccine) in Volunteers Aged 18-60 Years

Status Completed

Clinical Trial Summary

The Aim:

Study immunogenicity, confirm the safety and tolerability of different schedules of vaccination with "live cell-based vaccine against smallpox and other orthopoxvirus infections (VAC∆6 vaccine) based on vaccinia virus" using a complex of clinical and laboratory-instrumental techniques.

The research tasks are to:

1. To study the immunological activity of a single VAC∆6 vaccine dose of 1x10⁷ plaque-forming units (PFU).

2. To study the immunological activity of two VAC∆6 vaccine doses (given 28 days apart) of 1x10⁶ PFU.

3. Assess the safety of different VAC∆6 vaccination schedules using a set of clinical and laboratory-instrumental techniques (thermometry, measurement of blood pressure, heart and lung auscultation, ECG, common blood and urine tests, biochemical, immunological and virological studies).

4. Assess the reactogenicity of different VAC∆6 vaccination schedules (number of local and systemic reactions, the percentage of those vaccinated with systemic and local reactions of various severity degrees).

5. To identify VAC∆6 vaccine-associated adverse events.

6. Study cell-mediated immunity induced by different VAC∆6 vaccination schedules.

7. Determine the presence of the virus in specific skin formations (crusts, pustules), saliva, blood and urine.

8. Evaluate the protective efficacy of one and two doses of the studied VAC∆6 vaccine.

Clinical Trial Description

This is a Double-blind, Comparative, Randomized, Placebo-controlled Study on Immunogenicity, Reactogenicity and Safety of Live Cell-Based Vaccine Against Smallpox and Other Orthopoxvirus Infections (VAC∆6 Vaccine) Based on Vaccinia Virus in 18-60-year-old Volunteers.

The study included 334 healthy volunteers of both sexes aged 18-60 years who met the inclusion criteria and had no exclusion criteria.

The study was carried out in two stages:

The first stage is an open comparative study of the safety, reactogenicity, immunological activity and protective efficacy of VAC∆6 vaccine in parallel groups of 30 volunteers aged 18 to 60 who met the inclusion criteria. Volunteers were divided into two groups:

• Group 1: 15 volunteers who received a single intradermal VAC∆6 dose of 1x10⁷ PFU. Live smallpox vaccine was administered by scarification 2 months after the vaccination.

• Group 2: 15 volunteers who received two intradermal VAC∆6 doses of 1x10⁶ PFU (given 28 days apart). Live smallpox vaccine was administered by scarification one month after the full vaccination series.

The second stage is a Double-blind, Comparative, Randomized, Placebo-controlled study on Immunogenicity, Reactogenicity, and Safety of the VAC∆6 Vaccine in Parallel Groups. Randomization was carried out using the envelope method. The sealed opaque envelopes included in the Investigator's File were distributed to the clinical sites in the required quantity prior to the start of the study.

Substances were submitted for testing in encrypted form. The encryption technique was chosen and implemented by the sponsor - FBRI SRC VB "Vector", Rospotrebnadzor. Decryption was carried out after study report submission to the Federal Budgetary Research Institution, State Research Center of Virology and Biotechnology "Vector", Rospotrebnadzor.

A total of 304 volunteers aged 18-60 took part in the second stage of the clinical study, of which 158 were men and 146 were women, who met the inclusion criteria and had no exclusion criteria. The volunteers were assigned to study sites as follows:

1. FGBUZ MSCH-163, FMBA Russia - 272 volunteers randomized into four groups:

• Group 3: 76 volunteers who received two intradermal VAC∆6 doses of 10⁶ PFU/0.2 ml (given 28 days apart);

• Group 4: 76 volunteers who received two intradermal placebo doses of 0.2 ml (given 28 days apart);

• Group 5: 60 volunteers who received a single intradermal VAC∆6 dose of 10⁷ PFU/0.2 ml;

• Group 6: 60 volunteers who received a single intradermal placebo dose of 0.2 ml.

2. State Budgetary Health Institution of the Novosibirsk Region "Municipal Infectious Disease Clinical Hospital No. 1" - 32 volunteers randomized into two groups:

• Group 7: 16 volunteers who received a single intradermal VAC∆6 dose of 10⁷ PFU/0.2 ml;

• Group 8: 16 volunteers who received a single intradermal placebo dose of 0.2 ml.

• Before applying for a state license to the Ministry of the Russian Federation on May 4, 2022, the VACΔ6 vaccine was renamed to OrthopoxVac. ;

Related Conditions & MeSH terms

• Infections
• Monkeypox
• Smallpox
• Vaccinia

• NCT number: NCT05846243
• Study type: Interventional
• Source: Federal Budgetary Research Institution State Research Center of Virology and Biotechnology "Vector"
• Status: Completed
• Phase: Phase 2/Phase 3
• Start date: October 1, 2021
• Completion date: April 1, 2022