Japanese encephalitis vaccine support

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Lao PDR became the first country to conduct a JE campaign with Gavi support in 2015

1.6 million children immunised by the end of 2015

Rice paddies, prevalent throughout Southeast Asia, are breeding grounds for mosquitos that carry the Japanese encephalitis virus.

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

In April 2015, the Lao People’s Democratic Republic (Lao PDR) became the first country to run a Gavi-supported Japanese encephalitis (JE) campaign – just 18 months after WHO added a JE vaccine developed by Chengdu Institute of Biological Products to the list of prequalified vaccines that United Nations agencies can procure. This was the first-ever WHO prequalification for a vaccine produced in China.

Following the success of the catch-up campaign, Lao PDR added JE vaccine to its routine immunisation schedule. So far, 1.6 million children have been immunised with support from Gavi.

In June 2016, the Gavi Board agreed to co-finance countries’ routine Japanese encephalitis vaccine programmes in addition to funding catch-up campaigns. As a result, Gavi is increasing its support for this life-saving vaccine and helping the region take the necessary steps to reduce the JE disease burden in the long term.

Nepal, Cambodia, Vietnam and Myanmar have also applied and been approved for support, with campaigns scheduled for 2016 and 2017. The Alliance has drawn on the strengths of its individual partners to accelerate access to JE vaccine, which has a long manufacturing lead-time. WHO, UNICEF’s Supply Division, PATH and the Bill & Melinda Gates Foundation all play a critical role in ensuring sufficient supply of the vaccine to countries.

Spread by mosquitos, Japanese encephalitis is the main cause of viral encephalitis in Asia

Case-fatality rates are estimated at 20–30%, while up to 30% of survivors suffer permanent disability

Outside of Asia, Japanese encephalitis (JE) is relatively unknown, but more than three billion people live in areas at risk of the viral disease. JE is especially prominent in the poor rural communities of eight Gavi-eligible countries in South-East 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 up to 30% of those infected. According to the World Health Organization (WHO), mortality is estimated at between 13,600 and 20,400 deaths each year. However, awareness of the disease is low and the figures may underestimate the real impact. In 2005, a devastating outbreak of JE killed nearly 2,000 people in India and Nepal, mostly children.

JE’s lifelong toll on its survivors is even less known. In the most severe cases, an estimated 30% of cases result in permanent neurological weaknesses, with an even higher rate reported in children.

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 is then transmitted to humans by mosquitoes.

JE cannot be transmitted from one person to another.

Vaccine-preventable

There is no specific treatment for JE. Prevention of the disease through 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 allows countries to reach children aged between 9 months and 14 years through catch-up campaigns and routine immunisation.

Burden of disease

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

Risk factors for JE include living in close proximity to pigs and to irrigated rice fields.

Gavi supports JE catch-up campaigns and co-finances the vaccine for routine immunisation

Students in Vientiane, Lao People’s Democratic Republic, after receiving their first dose of Japanese encephalitis vaccine.

Students in Vientiane, Lao People’s Democratic Republic (PDR), after receiving their first dose of Japanese encephalitis (JE) vaccine. In 2015, Lao PDR became the first country to use support from Gavi to protect its children from JE. Credit: Bart Verweij

In 2014, Gavi invited countries to apply for support to introduce the Japanese encephalitis (JE) vaccine. The first Gavi-funded JE vaccine campaigns started in Lao People’s Democratic Republic in 2015, with Nepal and Cambodia scheduled for 2016.

In line with WHO recommendations, Gavi provides support for JE catch-up campaigns and co-finances the vaccine for use in routine immunisation programmes. The catch-up campaigns are intended to pave the way for countries to introduce the vaccine into the routine system.

The campaigns target children aged 9 months to 14 years and ensure sustainability by embedding JE vaccine into routine immunisation programmes. Where the vaccine is introduced into the routine system, children are vaccinated at 9 months.

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, and 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 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.

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 in the near future, adding to the choices available for countries.

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