Mpox Vaccine Phase II Trial - "BNT166-02 Study"

The BNT166-02 study is a Phase II clinical trial evaluating the safety, reactogenicity, and immunogenicity of BNT166a, a next-generation mRNA-based vaccine developed by BioNTech to prevent mpox (monkeypox). The study focuses on healthy individuals aged 12 years and above across selected African countries, including Tanzania, where the Ifakara Health Institute (IHI) is leading implementation efforts in Bagamoyo town and Fukayosi ward.

About Mpox
Mpox is a re-emerging viral disease with rising outbreaks in nearby countries such as the Democratic Republic of Congo, Uganda, Rwanda, and Kenya. While Tanzania has reported only a few confirmed cases, its proximity to these affected regions places it at elevated risk for transmission.

Currently, only two vaccines—MVA-BN (Modified Vaccinia Ankara–Bavarian Nordic) and LC16—have received emergency use authorization for mpox in the DRC. However, their limited availability and insufficient data on efficacy in African populations present a major gap in prevention strategies.

To help address this gap, the BNT166-02 study will assess BNT166a, which targets multiple mpox virus antigens using the same proven mRNA technology platform as BioNTech’s COVID-19 vaccine, COMIRNATY. By conducting this study in Tanzania and other African countries, the trial aims to generate evidence on the vaccine's safety, immune response, and suitability in diverse, high-risk populations—ultimately supporting national and global mpox prevention strategies.

Study Objectives

Primary Objective:

• To evaluate the safety and immune response (antibody levels) following vaccination with BNT166a.

Secondary Objectives:

• To monitor the kinetics of antibody responses and compare immunogenicity between adolescents and adults.

Exploratory Objective:

• To assess mpox case occurrence and explore threshold levels of immune protection.

Study Design and Population
The trial follows a randomized, observer-blind, placebo-controlled design, with participants categorized based on Orthopoxvirus exposure status. The total study population is approximately 2,760 participants, with Ifakara Health Institute responsible for enrolling 189 participants as part of a two-phase study.

Timeline and Funding
The study is funded by BioNTech and will run from May 27, 2025, to March 31, 2027.

Photo courtesy of SciTech Daily.