Bavarian Nordic’s MVA-BN vaccine, has become the first mpox vaccine to be added to the World Health Organization (WHO) prequalification (PQ) list, enabling its use globally.

The WHO has also recommended that single doses be given in supply-constrained outbreak situations instead of the usual two doses, and “off label” use for children as the vaccine is not yet approved for under-18s.

WHO Prequalification (PQ) and Emergency Use Listing (EUL) are mechanisms used to evaluate quality, safety and efficacy of medical products, such as vaccines, diagnostics and medicines, and product suitability for use in low- and middle-income countries. 

“PQ is based on the review of full set of quality, safety and efficacy data on medical products, including risk management plan and programmatic suitability,” according to a Friday media release from WHO.

“WHO’s assessment for prequalification is based on information submitted by the manufacturer, Bavarian Nordic, and review by the European Medicines Agency, the regulatory agency of record for this vaccine,” the WHO added.

A month ago, WHO Director General  Dr Tedros Adhanom Ghebreyesus declared mpox a public health emergency of international concern (PHEIC) as the outbreak intensified in the Democratic Republic of the Congo (DRC) and neighbouring countries.

Since the global outbreak in 2022, over 120 countries have confirmed more than 103 000 cases. 

This year, there have been 25 237 suspected and confirmed cases and 723 deaths from different outbreaks in 14 African countries (8 September 2024). Morocco reported its first case on Thursday.

‘Off label’ for children

“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,” said Tedros. 

“We now need urgent scale up in procurement, donations and rollout to ensure equitable access to vaccines where they are needed most, alongside other public health tools, to prevent infections, stop transmission and save lives.”

The MVA-BN vaccine (marketed as Jynneous and Imvamune) is administered in people over the age of 18 as a two-dose injection given four weeks apart. After prior cold storage, the vaccine can be kept at 2–8°C for up to eight weeks.

Although, MVA-BN is not yet registered for use in children, the WHO’s head of Research and Development, Dr Ana-Maria Restrepo, told a recent media briefing that the DRC could use the vaccine “off label” for children, and that there were a number of studies – including clinical studies – that had established its efficacy in children. The majority of mpox cases in DRC are in children.

The WHO also noted that it could be used “off-label” for pregnant and immuno-compromised people “in outbreak settings where the benefits of vaccination outweigh the potential risks”.

WHO has also recommended single-dose use in supply-constrained outbreak situations. Available data shows that a single-dose MVA-BN vaccine given before exposure has an estimated 76% effectiveness whereas the two-dose schedule offers an estimated 82% protection.

Help for national regulators

“The WHO prequalification of the MVA-BN vaccine will help accelerate ongoing procurement of the mpox vaccines by governments and international agencies such as Gavi and Unicef to help communities on the frontlines of the ongoing emergency in Africa and beyond,” said Dr Yukiko Nakatani, WHO Assistant Director-General for Access to Medicines and Health Products. 

“The decision can also help national regulatory authorities to fast-track approvals, ultimately increasing access to quality-assured mpox vaccine products,” he added.

The WHO’s Strategic Advisory Group of Experts (SAGE) on Immunization reviewed all available evidence and recommended the use of MVA-BN vaccine in mpox outbreaks for people “at high risk of exposure”. 

Bavarian Nordic CEO Paul Chaplin said that his company is “highly encouraged” by the PQ, “which is a testament to the strengths of our vaccine and the quality of data we have generated through numerous studies, as well as in real life”. 

Company aims for two million doses in 2024

“Bavarian Nordic has recently filed a submission to the European Medicines Agency to extend the approval to adolescents 12-17 years of age and is also working with partners, including the Coalition for Epidemic Preparedness Innovations (CEPI) to evaluate the safety and efficacy of the vaccine in children 2-12 years of age,” according to a company statement.

“While we continue to work with WHO and other regulatory bodies to expand the approval to include children, who are severely impacted by the mpox outbreak, we are pleased that this approval will help accelerate access to our vaccine for communities across the entire African continent and we applaud the WHO for their swift review and action to make this happen,” added Chaplin.

Bavarian Nordic has undertaken to focus its production efforts on MVA-BN, which will enable it to produce two million doses by the end of the year, and potentially 13 million by the end of 2025, the company reported on Thursday.

Dr Rogerio Gaspar, WHO Director for Regulation and Prequalification, said the global body was “progressing with prequalification and emergency use listing procedures with manufacturers of two other mpox vaccines: LC-16 and ACAM2000. We have also received six expressions of interest for mpox diagnostic products for emergency use listing so far”. 

The LC-16 vaccine, produced by Japan’s KM Biologics, is licensed for use in children.

Image Credits: US Centres for Disease Control .