Japanese encephalitis vaccine support

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10,000-15,000 people infected with Japanese encephalitis die each year

Proven effective vaccines are best control strategy

JE Paddy fields

Rice paddies, prevalent throughout Southeast Asia, may make for a beautiful landscape, but they are also optimal breeding grounds for mosquitos that carry the JE virus. Photo: PATH/2013

Outside of Asia, Japanese encephalitis (JE) is relatively unknown but some four billion people live in areas at risk of the viral disease. JE is especially predominant in the poor rural communities of eight Gavi-eligible countries in Southeast Asia and the Western Pacific.

The disease

Often called “brain fever”, JE begins with flu symptoms, progresses to a brain infection and claims the lives of 20 to 30 percent of infected infants and children. According to the World Health Organization (WHO), annual mortality is calculated at 10,000 to 15,000 deaths each year although awareness of the disease is low and the figures may significantly underestimate the impact. In 2005, a devastating outbreak of JE killed nearly 2,000 in India and Nepal, mostly children. 

JE’s lifelong toll on its survivors is even less well known. An estimated 30 to 50% of cases result in permanent neurological weaknesses, such as paralysis, recurrent seizures or the inability to speak.

Mosquito-borne

The virus is hosted by wading birds like herons and egrets, which flock to rice paddy fields and by the pigs commonly raised in rural areas. It’s then transmitted to humans by mosquitoes, which breed by the tens of thousands in rice paddies.

JE cannot be transmitted from one person to another.

Vaccine-preventable

There is no specific treatment for JE. Prevention of the disease through proven effective and relatively inexpensive vaccines is the best control strategy.

Some Gavi-eligible countries have already initiated JE vaccination programmes, either routine or campaigns. Gavi support will allow countries to reach all population groups at risk through catch up campaigns.

Japanese encephalitis - countries or areas at risk, 2012. Source: World Health Organization 

Japanese encephalitis - countries or areas at risk, 2012 

Burden of disease

The disease is endemic with seasonal distribution in parts of China, the Russian Federation’s south-east and South and South-East Asia. All year transmission is observed in tropical climate zones.

The spread of JE in new areas has been correlated with agricultural development and intensive rice cultivation supported by irrigation programmes.

Countries will be able to apply for Gavi support in 2014 allowing for the first campaigns in 2015

JE vaccination

JE is a leading cause of viral disability in Asia, and there is no treatment or cure. Immunisation is the best means to control it. Photo: PATH/2013

Gavi has issued guidelines inviting countries to apply for support to introduce the Japanese encephalitis (JE) vaccine. The first Gavi-funded JE vaccine campaigns should follow at the start of 2015.

In line with WHO recommendations, Gavi is providing support for JE catch up campaigns on the basis that countries self-finance the introduction of the vaccine in their routine immunisation programmes.

The campaigns will target children aged 9 months to 15 years and ensure sustainability by embedding JE vaccine into routine immunisation programmes. This catalytic support will have a sustainable and positive impact on JE control efforts.

Prequalification

In 2011, the Gavi Board recommended opening a window for country applications for Gavi support, pending the prequalification of an appropriate JE vaccine.

In October 2013, WHO added a JE vaccine, known as SA 14-14-2 and developed by China’s Chengdu Institute of Biological Products, to its list of prequalified vaccines, opening the door for United Nations agencies to procure the vaccine. It is the first Chinese-produced vaccine to be prequalified by WHO. This is also the first prequalified JE vaccine for paediatric use.

Recognising JE’s burden of disease, PATH has collaborated with the Chengdu Institute, WHO and ministries of health on clinic trials to demonstrate that the SA 14-14-2 vaccine, made from an active but weakened virus, is both safe and effective. It also only requires one dose.

PATH also negotiated with the manufacturer to ensure a special public-sector price affordable for low-income and some middle income countries at risk of JE transmission, such as the Philippines.

JE vaccines had existed for decades and WHO recommends immunisation in all regions where the disease is a recognised public health problem. Additional prequalified vaccines appropriate for paediatric use are expected to be prequalified, adding to the choices for immunisation.

24%

In total, 24% of children in Gavi-supported countries are not being vaccinated.

WHO/UNICEF

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