Moderna’s mRNA Mpox Vaccine Shows Superior Efficacy in Early Testing

In a groundbreaking study published in the journal Cell, Moderna’s experimental mRNA vaccine for monkeypox, also known as mpox, has demonstrated superior efficacy compared to currently licensed vaccines. This collaborative research, conducted by scientists from Moderna, the US Army Medical Research Institute of Infectious Diseases, and other institutions, utilized nonhuman primates to evaluate the performance of the new vaccine. The findings are particularly significant given the ongoing mpox outbreak in Central Africa, which has been declared a public health emergency by the World Health Organization (WHO).

The study involved a direct comparison between Moderna’s mRNA vaccine and the already-licensed Bavarian Nordic vaccine. The results were striking: all vaccinated animals survived exposure to a lethal strain of the virus, whereas most unvaccinated animals succumbed to the infection. Moreover, the animals that received Moderna’s vaccine exhibited a stronger immune response and reduced disease severity compared to those vaccinated with the Bavarian Nordic shot. This suggests that the mRNA technology employed by Moderna may offer a more potent and safer alternative to traditional vaccine approaches.

One of the most compelling aspects of Moderna’s mRNA vaccine is its ability to lower the viral load in both blood and throat swabs of the vaccinated animals. This indicates a potential reduction in transmission, a crucial factor in controlling the spread of the virus. Senior author Jay Hooper emphasized that the mRNA technology allows for the production of a highly targeted and effective vaccine, which could be a game-changer in the fight against mpox. The current outbreak, driven by a more severe variant of the virus, underscores the urgent need for effective vaccination strategies.

Monkeypox is a viral illness caused by the monkeypox virus, which can lead to severe symptoms and even death, particularly in vulnerable populations such as children, pregnant individuals, and those with compromised immune systems. The WHO’s declaration of a public health emergency highlights the gravity of the situation, as this is the second time in recent years that such a declaration has been made for mpox. The previous global outbreak in 2022 had already put a spotlight on the limitations of existing vaccines, making the development of new, more effective options a top priority.

The current mpox outbreak has not been confined to Africa alone; cases have been reported in various countries around the world. This global spread further complicates efforts to contain the virus, especially given the limitations of existing vaccines. Factors such as cost, availability, and effectiveness have hindered the widespread use of authorized vaccines, making the development of Moderna’s mRNA vaccine all the more critical. The ongoing testing in nonhuman primates and humans aims to assess the safety, tolerability, and immune response of this new vaccine candidate.

Vaccines work by training the body’s immune system to recognize and fight off pathogens in a safer manner than natural exposure. Traditional vaccines often use weakened or inactivated versions of the germ, while mRNA vaccines provide genetic instructions for the body to produce a part of the germ itself. This innovative approach has already proven successful with Moderna’s coronavirus vaccine, and the early results for the mpox vaccine are equally promising. By targeting four key proteins found in all known poxviruses, Moderna’s vaccine aims to offer broad and robust protection.

In the study, six macaques were vaccinated with Moderna’s mRNA vaccine, while another six received the Bavarian Nordic vaccine. Eight weeks after the initial dose, all 12 vaccinated macaques were exposed to a lethal strain of mpox. A control group of six unvaccinated macaques was also exposed to the virus. The health of the animals was closely monitored, and blood samples were taken to assess their immune response. The results were unequivocal: all vaccinated animals survived, while only one out of the six unvaccinated animals did not succumb to the virus.

Co-senior author Galit Alter from Moderna expressed excitement over the results, noting that the animals vaccinated with the mRNA vaccine showed less weight loss and developed fewer lesions compared to those given the live attenuated vaccine. Furthermore, the period during which the animals exhibited lesions was shortened by more than 10 days, and the viral loads in their blood and throat swabs were significantly lower. These findings suggest that Moderna’s mRNA vaccine not only provides direct protection but also reduces the duration and severity of the disease.

The promising results from the animal study have paved the way for early-stage human clinical trials. The vaccine candidate, named mrna-1769, is currently being tested in the UK to assess its safety and immune response in humans. Preliminary results from these trials are eagerly anticipated, as they will provide crucial data on the vaccine’s potential to combat the ongoing mpox outbreak. If successful, Moderna’s mRNA vaccine could become a vital tool in the global effort to control and eventually eradicate mpox.

In addition to its efficacy against mpox, the serum from the vaccinated macaques was tested against other viruses in the orthopox family, including smallpox. The results were encouraging, as the serum effectively neutralized these related viruses. This broad-spectrum protection is particularly important given the potential for bioterrorism and the need for vaccines that can safeguard against multiple threats. The use of mRNA technology offers a versatile platform that can be rapidly adapted to target emerging pathogens.

The development of Moderna’s mRNA vaccine for mpox represents a significant advancement in vaccine technology. The ability to produce a highly targeted and effective vaccine using genetic instructions rather than live attenuated viruses addresses many of the limitations of traditional vaccines. As the world grapples with the challenges of controlling infectious diseases, innovations like these are essential for improving public health outcomes. The early success of Moderna’s mpox vaccine in animal studies is a hopeful sign that we may soon have a powerful new weapon in the fight against this deadly virus.

As we await further results from human clinical trials, the scientific community remains optimistic about the potential of mRNA vaccines to revolutionize our approach to infectious diseases. The rapid development and deployment of mRNA vaccines during the COVID-19 pandemic demonstrated the technology’s promise, and its application to other diseases like mpox could yield similarly transformative results. Continued research and collaboration will be key to unlocking the full potential of mRNA vaccines and ensuring that they are accessible to populations in need around the world.