Nipah Virus Cases in Asia Increase Pressure to Develop a Vaccine

On Jan. 26, 2026, the government of India confirmed two cases of Nipah virus (NiV) infection in its state of West Bengal. Both cases involved health care workers in a hospital in the district of North 24 Parganas. One of the individuals died after being hospitalized on Jan. 28. Contact tracing linked a total of 196 individuals who were reported to be asymptomatic and tested negative for the virus.^{1 2 3 4 5}

Concern over the possible spread of the Nipah virus has lead some Asian countries—specifically Indonesia, Malaysia, Nepal, Pakistan, Singapore, Thailand, and Vietnam—to begin screening passengers at airports that receive flights from West Bengal and at some land border points of entry with India. On Feb. 3, a case of NiV in the neighboring country of Bangladesh was confirmed by the International Health Regulations National Focal Point (IHR NFP).^{2 3}

An assessment of the evolving situation in India and Bangladesh by the World Health Organization (WHO) gauged the risk posed by NiV to be “low at the national, the regional and global level.” According to the WHO, “The risk of international disease spread is considered low.”²

The WHO’s Director-General, Tedros Adhanom Ghebreyesus, has referred to NiV as a “rare but serious disease.”² He said:

Authorities have increased disease surveillance and testing, implemented prevention and control measures in health care settings, and are keeping the public informed about how to protect themselves.²

NiV Spreads from Animals to Humans

The WHO described NiV as a “zoonotic virus, usually transmitted from animals to humans.” It notes, though, that the virus can also be “transmitted through contaminated food or directly between people.” The incubation period (from time of infection to the onset of symptoms) typically ranges from three to 14 days.^{1 6}

While some people infected with NiV develop no symptoms, WHO officials note most people develop a fever and symptoms involving the brain, such as headaches or confusion, and the lungs, such as difficult breathing or coughing. Other common symptoms my include chills, fatigue, drowsiness, dizziness, vomiting, and diarrhea. Severe symptoms of NiV infection can include encephalitis (swelling of the brain) and death.⁶

Severe disease can occur in any patient but is particularly associated with people presenting with neurological symptoms, with progression to brain swelling (encephalitis) and, frequently, death—usually more associated with individuals with pre-existing neurological conditions.⁶

The main diagnostic test for NiV infection is real time polymerase chain reaction (RT-PCR) of respiratory samples, as is the case for COVID-19. Blood or cerebrospinal fluid (a spinal tap) samples can also be used to determine infection, as can blood antibody detection via enzyme-linked immunosorbent assay (ELISA).⁶

NiV Vaccine Trials Underway

There are currently no specific medical treatments for NiV infection. There are no approved drugs or vaccines for it. But WHO officials have identified NiV as a high priority pathogen because, they say, it kills up to 82 percent of people infected with it. An NiV vaccine is already being developed.⁶

A small (173 participants) Phase 1 clinical trial on a recombinant NiV vaccine, identified as HeV-sG-V, was completed late last year. The trial was funded by the Coalition for Epidemic Preparedness Innovations (CEPI), which was established in 2017 for the purpose of accelerating the development of vaccines to respond to epidemics and pandemics. The results of the NiV vaccine trial were published in The Lancet on Dec. 13, 2025. The conclusion was that “three doses and regimens of HeV-sG-V had a tolerable risk profile and were able to induce an immune response.”⁷

Meanwhile, a small (306 participants) Phase 2 clinical trial on another NiV vaccine candidate, ChAdOx1 NipahB, was launched in December. That NiV vaccine uses the same viral vector platform as the Oxford University/AstraZeneca COVID vaccine. The ChAdOx1 NipahB vaccine trial is also being funded by CEPI, whose key funders include U.S. federal agencies such as NIH; European Commission; the Bill & Melinda Gates Foundation, and Wellcome.^{8 9}

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