An experimental vaccine from Moderna against MPOX has shown greater effectiveness than current vaccines in reducing symptoms and the duration of the disease, according to an animal study published September 4 in the journal CellularThis announcement comes as Africa is experiencing a resurgence of MPOX, which with the appearance of a new variant (1b) prompted the World Health Organization (WHO) to trigger its highest level of global health alert on August 14.
Same technology for its coronavirus vaccine
Researchers used mRNA technology to try to find a vaccine against MPOX that would be highly effective and safe, virologist and lead author of the study Jay Hooper of the US Army Medical Research Institute of Infectious Diseases told AFP.
Of the mpox vaccines, formerly called monkeypox, were originally developed to combat human smallpox, a deadly disease that was declared eradicated by the WHO in 1980. The vaccine currently marketed as Jynneos in the United States, Imvanex in Europe and Imvamune in Canada is made from a "live attenuated" virus, meaning the virus has been weakened so that it cannot transmit the disease to humans.
But being attenuated, it is also less protective than the older generation ACAM2000 vaccine, which is however not recommended for all audiences because of its side effects. Moderna's new messenger RNA vaccine includes genetic instructions that train the immune system to recognize four antigens allowing the virus to attach to cells. The American laboratory uses the same technology for its coronavirus vaccine, which is very safe and effective.
Next tests on humans
In the study, six macaques were vaccinated with the mRNA vaccine, and six others were given an injection of the currently marketed vaccine. Eight weeks after the first injection, all 12 macaques were exposed to a deadly strain of mpox. Another group of six unvaccinated macaques were also exposed to the virus.
All vaccinated monkeys survived, regardless of the vaccine used, and five of the six unvaccinated macaques died. But if we focus specifically on the results of the mRNA vaccine, what we have seen has been very surprising and exciting.", Galit Alter, a virologist and immunologist at Moderna and another lead author of the study, told AFP.
Primates vaccinated with mRNA lost less weight and had fewer lesions than those injected with the attenuated vaccine. In addition, the mRNA vaccine reduced the time during which lesions were visible on the macaques by nearly 10 days. Viral loads in blood and throat swabs were also lower, suggesting that it also reduces the risk of transmission.
Alec Freyn of Moderna, another author of the study, told AFP that the vaccine had also been tested for other viruses in the same family and had been shown to be effective against cowpox, cowpox, rabbitpox and camelpox. The vaccine, called mRNA-1769, is now undergoing initial human clinical trials in the UK to ensure it is safe.
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