WHO prequalifies the first vaccine against Mpox

The World Health Organisation (WHO) has announced the addition of the MVA-BN vaccine to its prequalification list, marking the first vaccine prequalified for mpox. This step is expected to significantly accelerate access to the vaccine in communities where controlling the spread of mumps is a priority.

The vaccine, produced by Bavarian Nordic A/S, underwent a rigorous review process with the European Medicines Agency, its regulatory body. WHO Director-General Dr Tedros Adhanom Ghebreyesus highlighted the importance of this development in the ongoing fight against mpox, particularly in Africa, where outbreaks have been persistent. He emphasised the need for urgent global action in procuring and distributing the vaccine to ensure equitable access for those most in need.

The MVA-BN vaccine is recommended for people aged 18 and older and is administered as a two-dose injection, with the second dose given four weeks after the first. It can be stored at standard refrigeration temperatures (2-8°C) for up to eight weeks. Although the vaccine is not licensed for people under 18, WHO suggests that it may be used off-label in younger individuals, pregnant women, and those with compromised immune systems in high-risk situations.

Dr Yukiko Nakatani, WHO Assistant Director-General for Access to Medicines and Health Products, stated that the prequalification would expedite procurement by international organisations such as Gavi and UNICEF, helping to bring the vaccine to the regions most affected by the ongoing mpox emergency. Additionally, this decision may encourage national regulatory authorities to fast-track approvals, thereby increasing global access to this crucial vaccine.

The WHO Strategic Advisory Group of Experts (SAGE) on Immunisation has thoroughly reviewed available evidence and recommended the use of the MVA-BN vaccine during mpox outbreaks, particularly for those at high risk of exposure. In situations where vaccine supply is limited, WHO advises administering a single dose to stretch resources. Data has shown that a single dose of the MVA-BN vaccine can be 76% effective in preventing mpox when given before exposure, while the two-dose schedule increases effectiveness to 82%.

Vaccination after exposure to the virus is generally less effective, emphasising the importance of pre-exposure vaccination in high-risk populations. Additionally, the MVA-BN vaccine has demonstrated a strong safety profile and consistent performance in clinical trials and real-world use during the ongoing global outbreak, which began in 2022.

As the virus continues to evolve, WHO emphasises the importance of collecting data on vaccine safety and effectiveness across different settings. Since the WHO Director-General declared a public health emergency of international concern (PHEIC) in August 2024, the organisation has conducted assessments of the MVA-BN vaccine's suitability for emergency use and prequalification.

In addition to the MVA-BN vaccine, WHO is progressing with prequalification and emergency use listing procedures for two other mpox vaccines—LC-16 and ACAM2000. Furthermore, WHO has received expressions of interest from six companies for the emergency use listing of mpox diagnostic products, further expanding global capacity to detect and respond to outbreaks.

The ongoing mpox outbreak, particularly severe in the Democratic Republic of the Congo, was declared a PHEIC in August 2024. Since the global outbreak began in 2022, more than 103,000 cases of mpox have been confirmed across 120 countries. In 2024 alone, there have been over 25,000 suspected and confirmed cases, and 723 deaths reported from 14 African countries.

As the situation continues to unfold, WHO's prequalification of the MVA-BN vaccine marks a critical step in the fight against mpox, ensuring that vulnerable populations have better access to life-saving vaccines and tools to stop the spread of the disease.

Source: World Health Organisation