The Moderna laboratory has developed an experimental product to fight the new strain of the disease which is raging in Africa and appearing in Europe.
The technique used against Covid and awarded the 2024 Nobel Prize in Medicine could allow new advances. The Moderna laboratory published promising results from a study carried out on animals on Wednesday, September 4. This new vaccine reduces the symptoms and duration of the disease more effectively than the serums already on the market.
The study was conducted in a context of a surge in people affected by the virus in recent months, with faster and more contagious circulation. So far the number of reported cases exceeds that of the whole of 2023, with more than 15,600 cases and 537 deaths according to the World Health Organization (WHO).
The vaccine used today to combat the spread of Mpox was originally developed to combat human smallpox, a deadly disease that was declared eradicated by the WHO in 1980. 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. This is the vaccine model that is currently being distributed in several African countries affected by the epidemic.
Published in the journal Cell September 4, 2024, the study was led primarily by virologist Jay Hooper of the U.S. Army Medical Research Institute of Infectious Diseases. It is an already well-known technique, the use of messenger RNA, which has made it possible to develop a new vaccine against Mpox.
Messenger RNA (mRNA) is a molecule present in our cells and naturally produced by our body. The cellular system reads the information encoded by the mRNA and converts it into a protein. When a vaccine with mRNA is injected, the molecule will identify the protein of the virus to fight and convert into it. The protein then enters the cells of the virus and allows the body to trigger an appropriate immune response. The same technology had been used by the Moderna laboratory to generate an effective vaccine against Covid.
Encouraging results
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.
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 period 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.
The vaccine, called mRNA-1769, is undergoing initial clinical trials in humans in the UK to ensure it is safe. The trials began on 15 August and are expected to be completed by 13 June 2025, according to Moderna’s estimates. The primary goal is prevention, so it’s about assessing safety and immunogenicity – a person’s ability to mount an immune response.
The rollout of the mRNA vaccine comes as Africa experiences a surge in Mpox – previously known as “monkey pox”caused by the appearance of a new variant (clade 1b). An increase in cases that prompted the World Health Organization (WHO) to trigger its highest level of global health alert on August 14. In France, as a preventive measure, a second dose of vaccine was recommended on Monday, September 2 by the High Authority for Health (HAS).
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