Since then Nipah has returned almost every year in Bangladesh, and at intervals in India. In 2026 an outbreak occurred in West Bengal. The World Health Organization keeps it among its priority pathogens, as do the international coalition for epidemic preparedness and the American national institutes of health.
The case fatality rate reported in the literature runs between forty and seventy-five per cent. In some individual outbreaks it has been higher: in 2007, at Nadia in India, every identified patient died. Survivors often carry neurological consequences, and the encephalitis can return months or years after the initial infection.
So far, the profile of a candidate for the next pandemic. But there is one number that rarely reaches the headlines, and it changes the picture.
The basic reproduction number of Nipah is estimated at around 0.48. That is the number of people an infected person passes the virus to, on average, in a wholly susceptible population. Below one means the chain extinguishes itself: each infected person infects on average fewer than one other, and after a few steps the outbreak dies.
The estimate appears in a risk assessment published on 7 September in Frontiers of Medicine by Limei Wang and Hong Jiang, of the Fourth Military Medical University in Xi’an. It is a short perspective article on the probability that the 2026 Indian outbreak reaches China.

Their conclusion, worth reporting because it runs opposite to the way the news was relayed, is that this risk is low.
There are four reasons. The reproduction number below one, which limits sustained transmission. The high lethality, which shortens transmission chains further, because a severely ill patient does not travel and does not meet strangers. The geographical distance between the affected area and China, with no shared border and limited routine movement of people and goods. And the fact that the Indian authorities contained the outbreak with isolation and contact tracing, as they had done before.
The authors add that Chinese customs have monitored Nipah since 2018, that national guidelines were issued in 2021, and that in 2022 the Ministry of Agriculture placed the disease on its list of zoonoses.
Their concerns are about the coming decade, not today: the distribution of Pteropus fruit bats, which includes parts of China; the rising frequency of outbreaks in neighbouring countries; growing exchanges between the southern provinces and South and Southeast Asia; and ecological change linked to land use and extreme climate events such as El Niño. The 1998 Malaysian outbreak has been connected to climate-driven bat migrations.
One qualification is needed here that the authors do not make and that the reader deserves: that similar viruses circulate in bats in southern China is an ecological hypothesis, not an observation. Nobody has isolated Nipah in those populations.

Return to the number below one, because it explains the most important thing in this story.
Twenty-eight years after Malaysia, against a virus that kills up to three patients in four, there is no licensed vaccine and no specific drug. The reason is not scientific and it is close to a paradox: the disease is too rare and too poorly transmissible for anyone to demonstrate that a vaccine works.
A phase three trial, the one that precedes licensing, requires vaccinating thousands of people, leaving as many unvaccinated, and waiting until enough of them fall ill in both groups for the results to be compared. With Nipah this is not feasible. Outbreaks are small, unpredictable, often identified late, and burn out within weeks. There is neither the time nor the numbers.
The field has therefore moved in another direction, and this is the most interesting and least reported part.
By early 2026 four vaccine candidates were in clinical trials, built on four different technologies: a chimpanzee adenovirus vector, a vector based on vesicular stomatitis virus, a messenger RNA vaccine and a recombinant subunit vaccine.
The PHV02 candidate, a live attenuated vector expressing the glycoprotein of the Bangladesh strain, is entering phase two in Bangladesh itself, the country where people die of Nipah almost every year. The international coalition for epidemic preparedness has committed 17.3 million dollars to the trial, which plans to enrol around five hundred adults and seventy-five children.
ChAdOx1 NipahB, developed at the University of Oxford, has received PRIME designation from the European Medicines Agency, which accelerates the regulatory path for medicines addressing unmet needs.

The messenger RNA vaccine mRNA-1215 has completed phase one with immune responses that persisted a year after the boost, and its authors recommend proceeding with doses above ten micrograms in areas where the virus circulates.
The strategy that emerges is different from the usual one. Rather than waiting for a demonstration of efficacy that may never come, a reserve of investigational doses is being built, up to a hundred thousand for the Oxford candidate, ready to be deployed during an outbreak within a research protocol. If the vaccine works, the data are gathered while those exposed are protected. The international coalition calls this reserve its single highest priority for Nipah over the next two years.
There is, finally, a symmetry worth noting, because it bears on how we think about epidemics.
Nipah is frightening and does not spread, and the two facts are connected. A virus that kills quickly loses its host before it can use it: the patient is too ill to move, to meet strangers, to board a plane. It is the same mechanism that limits Ebola.
The pathogens that become pandemic are those that leave us on our feet long enough. Nipah does not, and for that reason it will probably never reach Europe in epidemic form.
Which makes it no less serious for those living in Bangladesh or Kerala, where every winter someone drinks contaminated palm sap and dies. The distinction between danger to the individual and danger to a population is exactly the one public debate keeps collapsing.

References
Wang L., Jiang H., "International risk assessment of Nipah virus outbreak and medium-long-term prevention and control prospects in China", Frontiers of Medicine, received 31 January 2026, accepted 16 March 2026. doi: 10.1007/s11684-026-1249-4
Barua S., Dénés A., "Global dynamics of a compartmental model for the spread of Nipah virus", Heliyon, 9(9):e19682, 2023, for the basic reproduction number estimate.
Nikolay B. et al., "Transmission of Nipah Virus - 14 Years of Investigations in Bangladesh", New England Journal of Medicine, 380(19):1804-1814, 2019.
Sun Y.Q. et al., "Mapping the distribution of Nipah virus infections: a geospatial modelling analysis", The Lancet Planetary Health, 8(7):e463-e475, 2024.
Chan X.H.S. et al., "Therapeutics for Nipah virus disease: a systematic review to support prioritisation of drug candidates for clinical trials", The Lancet Microbe, 6(5):101002, 2025.
"A structure-based mRNA vaccine for Nipah virus in healthy adults: a phase 1 trial", full text freely available at PubMed Central, PMC13099371.
Coalition for Epidemic Preparedness Innovations, announcement on PHV02 entering phase 2 in Bangladesh, 10 July 2025, and documentation on the investigational dose reserve.
Gavi, "Nipah vaccines set to enter human trials", 15 July 2025, for the PRIME designation of the Oxford candidate.