A vaccine candidate against the deadly Nipah virus is set to begin early-stage human trials in April. This offers new hope against one of the world’s most dangerous emerging infections. The vaccine has been developed by researchers at the University of Tokyo. It will be tested in a Phase 1 clinical trial in Belgium, according to a report by Nikkei Asia.
Nipah virus was known for its high fatality rate and unpredictable outbreaks. Health authorities reported that the virus could kill between 40 percent and 75 percent of those infected. The outcome depended on early diagnosis and access to medical care. Despite this danger, there is no licensed vaccine or specific treatment available. This makes prevention efforts extremely difficult.
Researchers in Japan developed the new vaccine candidate using a scientific approach that had already proven safe in other diseases. According to researchers, they inserted a small portion of the Nipah virus genetic material into a weakened measles virus. Vaccination programs around the world have widely used this modified measles virus for decades.
“When we introduce the vaccine in humans, the body produces antigen proteins similar to those of the Nipah virus. We see the immune system’s response strengthening the body’s defenses, helping to prevent the onset of symptoms,” the researchers explained. They added that they chose the modified measles virus platform because of its long history of global use and safety.
Before moving into human trials, the research team tested the vaccine in animal studies, including experiments involving hamsters. These trials showed encouraging results, with scientists confirming both safety and a strong immune response. Based on these findings, regulators approved the move to Phase 1 human trials.
The upcoming Phase 1 clinical trial in Belgium will include 60 healthy adult volunteers. The goal of this phase is not to confirm whether the vaccine could stop Nipah outbreaks. Instead, it must ensure safety for humans and trigger an immune response. Researchers emphasized that this is important before moving to larger and more complex trials.
The trial attracted attention as health authorities again report Nipah virus cases in South Asia. In January, India confirmed two Nipah infections in West Bengal, placing public health authorities on alert. While outbreaks are usually small, experts warned that each case carried a serious risk. This is due to the virus’s high death rate and potential for hospital-based transmission.
Nipah virus is classified as a zoonotic disease, meaning it spreads from animals to humans. Scientists consider fruit bats the natural hosts. Infections occur through contaminated food or infected animals such as pigs. Also, infections can occur through close contact with infected people. Human-to-human transmission is especially dangerous in healthcare settings where prolonged exposure occurs.
In humans, Nipah infection ranged from mild symptoms to severe illness. Patients often experienced fever and headaches at first. But in many cases the disease progressed rapidly, leading to breathing problems or fatal encephalitis, a severe swelling of the brain. Doctors limit treatment options to supportive care. This further highlights the need for a preventive vaccine.
The University of Tokyo’s effort is part of a broader international push to address the Nipah virus before it causes a larger crisis. A team linked to Oxford University started Phase 2 clinical trials of another Nipah vaccine candidate in Bangladesh in December. That study will include around 300 participants aged between 18 and 55. This shows growing global momentum.
The World Health Organization had already identified the Nipah virus as a priority disease under its Research and Development Blueprint. The designation reflected concerns that the virus had the potential to cause serious outbreaks if left unchecked. This is especially important in regions with frequent human-wildlife interaction.
Researchers and public health officials stressed that collaboration between countries is essential. Japanese scientists worked closely with European clinical centers to ensure that the trial met international safety standards. Experts said such cooperation is necessary for diseases that did not attract large commercial investment but posed serious global risks.
