An experimental vaccine from Moderna against MPOX has shown greater efficacy than current vaccines. It would reduce the symptoms and duration of the disease, according to an animal study. This announcement comes as Africa is experiencing a resurgence of the disease.
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Mpox virus: fear of a new epidemic
A promising discovery. An experimental vaccine from the Moderna laboratory against Mpox has shown greater efficacy than current vaccines in reducing the symptoms and duration of the disease, according to a study on animals whose results are published this Wednesday by the journal Cell. This announcement comes at a time when Africa is experiencing a resurgence of Mpox. Guinea has thus recorded its first case, the Ministry of Health of this West African country indicated this Wednesday, without further details.
Messenger RNA technology
In an attempt to find a vaccine against Mpox that would be highly effective and safe, researchers used messenger RNA technology, virologist and lead author of the study Jay Hooper of the US Army Medical Research Institute of Infectious Diseases told AFP. Vaccines against Mpox, formerly known as 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 composed of a virus “attenuated living”, which means that the virus has been weakened so that it does not transmit the disease to humans. But being attenuated, it is also less protective than the older generation vaccine ACAM2000, which is however not recommended for all audiences because of its side effects.
Moderna’s new mRNA vaccine, meanwhile, includes genetic instructions that train the immune system to recognize four antigens that allow the virus to latch onto cells. The American laboratory uses the same technology for its coronavirus vaccine, which is very safe and effective.
Next tests on humans
In this study, six macaques were vaccinated with the mRNA vaccine, and six others were injected with 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 saw was 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 macaques by almost 10 days. Viral load in blood and throat swabs was also lower, suggesting that it also reduces the risk of transmission.
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Alec Freyn of Moderna, another author of the study, told AFP that the vaccine had also been tested against 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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