WHO Prequalifies MVA-BN Vaccine: A Milestone in the Fight Against Mpox

The World Health Organization (WHO) has granted prequalification status to the MVA-BN vaccine, marking it as the first vaccine against mpox to be officially recognized. This crucial decision is expected to significantly enhance global access to this life-saving product, especially in regions experiencing urgent outbreaks.

The WHO’s prequalification process involves a thorough review of information submitted by the vaccine’s manufacturer, Bavarian Nordic A/S, as well as evaluations conducted by the European Medicines Agency (EMA). This rigorous assessment ensures that the vaccine meets the necessary standards of safety, efficacy, and quality.

Dr. Tedros Adhanom Ghebreyesus, WHO Director-General, emphasized the importance of this development. “This first prequalification of a vaccine against mpox is an important step in our fight against the disease, both in the context of the current outbreaks in Africa and in future,” he stated. He stressed the need for an urgent scale-up in procurement, donations, and rollout to ensure equitable access to the vaccine. The goal is to prevent infections, halt transmission, and save lives.

The MVA-BN vaccine, designed for individuals over 18 years of age, is administered in a two-dose regimen, with doses given four weeks apart. It requires initial cold storage but can be maintained at 2–8°C for up to eight weeks after prior cold storage. This stability is crucial for distribution in areas with limited infrastructure.

The prequalification of the MVA-BN vaccine is expected to expedite its procurement by governments and international agencies like Gavi and UNICEF. This will help address the immediate needs of communities affected by the ongoing mpox emergency in Africa and other regions. Dr. Yukiko Nakatani, WHO Assistant Director-General for Access to Medicines and Health Products, highlighted the significance of this decision: “The WHO prequalification of the MVA-BN vaccine will help accelerate ongoing procurement of the mpox vaccines by governments and international agencies to help communities on the frontlines of the ongoing emergency in Africa and beyond.”

The vaccine’s efficacy has been a point of significant focus. Data indicates that a single dose of the MVA-BN vaccine administered before exposure has an estimated 76% effectiveness in protecting against mpox. The two-dose schedule increases this effectiveness to approximately 82%. However, vaccination post-exposure is less effective than pre-exposure vaccination. Despite this, the WHO recommends using the vaccine in outbreak settings where the benefits outweigh the potential risks, including off-label use in infants, children, adolescents, pregnant individuals, and those who are immunocompromised.

The WHO Strategic Advisory Group of Experts (SAGE) on Immunization has reviewed the available evidence and supports the use of the MVA-BN vaccine for individuals at high risk of exposure during an outbreak. In situations where supply is limited, the WHO also suggests single-dose administration to maximize coverage.

The prequalification of the MVA-BN vaccine comes amidst escalating mpox outbreaks, notably in the Democratic Republic of the Congo and other countries, which led to the declaration of a public health emergency of international concern (PHEIC) by the WHO Director-General on August 14, 2024. Since the global outbreak began in 2022, more than 103,000 cases of mpox have been confirmed across over 120 countries.

Dr. Rogerio Gaspar, WHO Director for Regulation and Prequalification, underscored the significance of the prequalification: “The findings of the assessments are particularly relevant in the context of the declaration of a PHEIC related to the upsurge of mpox in Africa.” He noted that the WHO is also advancing with prequalification and emergency use listing procedures for two additional mpox vaccines, LC-16 and ACAM2000, and has received multiple expressions of interest for mpox diagnostic products.

The prequalification of the MVA-BN vaccine represents a crucial step forward in the global response to mpox, offering hope for better control of the disease and improved health outcomes for affected communities.