Japanese encephalitis—no longer neglected: A model for other new vaccines

October 30, 2018 by Dr. Nihal Abeysinghe and Dr. Kathleen Neuzil

No longer neglected? Japanese encephalitis is a model for new vaccines to prevent other tropical diseases.

Health center staff with Dr. Mukergee and children standing in front of Japanese Encephalitis poster, West Bengal, India, July 2006

Project leaders outside an immunization site during the Japanese encephalitis vaccine introduction in West Bengal, India in July 2006. Photo: PATH/Julie Jacobson

Thirty years ago, hundreds of children in rural Sri Lanka were suffering from an incurable mosquito-transmitted disease sometimes called “brain fever.” Japanese encephalitis (JE) infections were on the rise in remote rural areas, making it difficult to provide vaccinations or health services. While the country introduced the vaccine in areas where young children were most at risk, concerns about the efficacy and safety of the vaccine in use and its high per-dose cost limited the government’s ability to protect all people in newly-endemic areas.

At the time, JE was endemic across communities in Asia and the Western Pacific, with tragic consequences. Compounding the impact, many JE survivors pay a lifelong toll: up to half suffer long-term or permanent neurological damage such as paralysis, recurrent seizures, or the inability to speak.

Unfortunately, these and other neglected tropical diseases afflict many the world’s most vulnerable people in poor and rural areas. Neglected tropical diseases contribute to a cycle of poverty because when people become too ill or disabled to work or attend school, their families and communities suffer.

For a disease with no cure, prevention is key

For several decades, outbreaks of JE continued across India, Nepal, and other countries. PATH suspected that JE was a bigger problem than previously realized.

Our experts brought together global partners to create reliable tools to diagnose and track the disease. For the first time, there would be a shared understanding around the prevalence of JE, its health and economic burden on communities, and the opportunity to prevent its spread.

The key to prevention: immunization.

PATH surveyed the field for an affordable and reliable JE vaccine. They identified a little-known vaccine (CD-JEV) produced and used in China and worked with the manufacturer—Chengdu Institute of Biological Products (CDIBP)—to conduct critical studies that generated evidence of efficacy and safety. Importantly, CD-JEV only requires one dose, making it easier to fit into existing vaccine programs.

The vaccine needed to be affordable for broad use in low-income countries, so PATH negotiated with the vaccine manufacturer to establish a special public-sector price.

For CD-JEV to be more accessible to countries outside of China, it had to be certified through the rigorous World Health Organization (WHO) approval process, which PATH supported. As a result, CD-JEV became the first-ever vaccine produced by a Chinese manufacturer to receive prequalification from the WHO. This designation unlocked more affordable access to CD-JEV for Sri Lanka and other countries in the region.

Chinese JE vaccine in use in India, photo PATH/Julie Jacobson.

Packets containing the Chinese CD-JEV vaccine, a lifesaving vaccine against Japanese encephalitis that has reached more than 300 million children throughout Asia. Photo: PATH/Julie Jacobson

The impact: Millions of lives saved and improved

PATH provided vaccine introduction assistance to endemic countries including India, Nepal, Cambodia, Myanmar, Laos, Indonesia, and Sri Lanka. Rather than a one-size-fits-all approach, PATH developed working relationships with relevant stakeholders to ensure successful vaccine introduction, scale-up, and sustainability. Over 15 years, more than 300 million children in ten countries beyond China have been immunized against Japanese encephalitis.

Japanese encephalitis is no longer the threat it once was.

A model for other new vaccines

The approval, pricing, and introduction for CD-JEV offers a model for harnessing ingenuity that originates in low- and middle-income countries to improve health equity for the people who need it most.

Scaling this model to other diseases that disproportionally afflict people living in poor and rural areas—including priority introduction programs for dengue, typhoid, cholera, and other tropical diseases—has the potential to improve global health equity.

This is a shining example of the power of multiple sectors coming together to solve a global problem. PATH leveraged partnerships and long-standing relationships with country decision-makers, policy agencies, financing bodies, and national governments to turn a little-known vaccine into an internationally approved immunization tool that has become a turning point in the battle against this dreaded disease.

Progress and hope in Sri Lanka

In Sri Lanka, PATH helped with introduction of a low-cost vaccine at the country level and to sustain it as part of the national immunization program. Last year, the country reported only 23 cases—primarily among non-vaccinated adults. Thousands of children and families are protected and safe.