A new vaccine, under development for mpox, could give better protection against the virus than existing vaccines, a study in monkeys has shown.

Mpox is a disease caused by the monkeypox virus that commonly results in a rash and painful blisters, as well as flu-like symptoms.

Declared a public health emergency, in August, by the World Health Organization, the outbreak is concentrated in central Africa, particularly the Democratic Republic of the Congo, and has caused more than 600 deaths so far.

One of the more worrying aspects of this mpox strain (clade 1b) compared to previous ones is that it appears to cause more severe disease, and there is also some evidence it may transmit more readily between people.

Currently, there is no vaccine specifically for mpox – the vaccines that have been used, such as MVA, were originally developed for the related virus smallpox, but may not give the best protection.

However, a recent study on an experimental mRNA vaccine specifically for mpox, by US-based pharmaceutical company Moderna – which also developed a Covid-19 vaccine using the same technology – is more effective at limiting symptoms and reduced the duration of the disease in infected monkeys, compared to an existing MVA vaccine.

The mRNA technology, in the Moderna vaccine, allows only the parts of the virus most likely to induce a lasting immune response to be included (rather than the whole virus, as with MVA).

Senior author Jay Hooper, at the US Army Medical Research Institute of Infectious Diseases, said: “With the mRNA technology, we’re able to produce a vaccine that gives quite potent responses with a very tolerable safety profile.”

Clinical trials for the vaccine are already underway, and it is hoped it could help to boost the limited vaccine supplies that are urgently needed for this current outbreak.