Recognition of Japanese encephalitis leads to action

What do international travelers and 200 million children in China have in common? They were among the first people to be protected from the deadly and disabling virus that causes Japanese encephalitis.

This is the story of how the international public health community became more aware of the need for broader protection against Japanese encephalitis—and how a vaccine against JE will one day reach virtually everyone who needs it.

A growing awareness

In 2001 and 2002, PATH was working in the state of Andhra Pradesh, India, to help strengthen immunization services when we began to realize that JE was a bigger problem than anyone thought. District- and state-level health workers in Andhra Pradesh routinely voiced concerns about the disease, and improved surveillance of disease outbreaks suggested a high incidence of JE. PATH and our partners took immediate action, and within months a JE vaccine was successfully introduced in Andhra Pradesh.

By 2003, we had secured a grant from the Bill & Melinda Gates Foundation to tackle JE not just in one state in India but in the entire Southeast Asia and Pacific Region. Our goal was to understand the disease, determine the health and economic burden it placed on countries, and prepare the way for a vaccine that would safely and affordably prevent it.

A more thorough understanding

First, we began to establish reliable methods of diagnosing and tracking JE. Especially where resources were scarce, decision-makers in affected countries needed all the information they could get to set priorities.

We helped private-sector partners develop standard tests for diagnosing Japanese encephalitis, and we worked with the World Health Organization and governments to set up surveillance systems and a web-based platform for sharing data about JE incidence. These efforts would allow countries to understand the extent of JE, prioritize it, and focus prevention efforts on the regions and people most needing protection.

Outbreak

In 2005, media coverage of an outbreak focused international attention on JE and further strengthened the resolve of governments to find ways to protect against it. The outbreak of 6,500 JE cases claimed the lives of nearly 2,000 people—mostly children—in Nepal and India. The Indian state of Uttar Pradesh was particularly hard hit, leading the Government of India to swiftly develop a strategy to reduce future risk of JE in time for the next year’s JE season.

Hope hailed from China

With JE finally getting the attention it deserved, there was still the matter of how to control it. Consensus among global health experts was that a vaccine was the only practical hope.

In fact, vaccines against the disease already existed, and international travelers to Asia were routinely vaccinated against JE. But the commonly used vaccine had drawbacks that made it difficult to integrate into national immunization programs in developing countries. Three doses were required, there were side effects, and it was very time-consuming and expensive to produce. There simply wasn’t enough vaccine or funding for all the children who needed it.

In search of a solution, PATH surveyed the field for a better JE vaccine. We found that China had vaccinated more than 200 million children since 1988 with an effective vaccine made from active but weakened virus. Although the Chinese vaccine was safe, effective, affordable, and easy to administer in large campaigns—especially since only one dose was needed—language and cultural barriers had prevented information about its potential from being shared internationally.

Taking action

To get the word out about the Chinese vaccine, PATH began presenting at international meetings and translating available research as well as providing technical assistance to the vaccine manufacturer. We helped the manufacturer prepare data to pursue prequalification from the World Health Organization to make it easier for other countries to import the vaccine, and we helped to support construction of a new factory. We also supported clinical trials to confirm that the vaccine can be given at the same time infants get their measles shots, which would make it easier to fit into existing immunization programs and dramatically increase the number of children who receive protection against JE. To help countries plan for introduction of the vaccine, we applied available data to model the cost-effectiveness of immunization strategies—either integrating JE vaccine into immunization programs or combining routine vaccination with mass campaigns to vaccinate at-risk children and adolescents.

One of our greatest accomplishments has been working with the vaccine manufacturer and countries to better forecast demand for the vaccine and to negotiate prices that developing countries can afford.

Precedent-setting protection

These activities, together with the work of our many partners around the world, have put JE on the fast track to control. India alone vaccinated more than 60 million children between 2006 and 2009 (read more about it here), and other countries—including Cambodia, Vietnam, and Sri Lanka—are on track to expand their immunization programs.