POST 00926E : JE VACCINE INTRODUCTION
Follow-up on Post 00912E and 00920E
18 May 2006
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Julie Jacobson (mailto:
[email protected]) from PATH is sending a
substantial update on JE Vaccine introduction. For more information,
please contact: [
[email protected]]
[email protected][/email]
or visit the Japanese Encephalitis Project Website at :
http://childrensvaccine.org/html/jep.htm
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In response to the recent exchange on TechNet concerning Japanese
encephalitis (JE) vaccine introduction, and India's decision to introduce
JE vaccine specifically, I would like to provide an update and hopefully
clarify a few points. JE vaccination remains the best known way to prevent
the disease and, increasingly, countries seeking to prevent JE have
vaccine options available to protect their populations.
Last year, a JE outbreak with 6,584 cases claimed over 1,800 lives in
India. Subsequently, and after careful review of its options, the Indian
ministry of health and family welfare decided to import the live,
attenuated vaccine known as the SA 14-14-2 vaccine from a Chinese
manufacturer. This vaccine has been shown to be a highly effective and
safe vaccine, with almost 20 years' experience of its use in China. It is
the only internationally licensed JE vaccine currently available in
sufficient supply to meet the needs of the Indian immunization program.
India intends to begin immunizing in high-risk districts this year.
Similarly, Nepal has decided to import the SA 14-14-2 vaccine for
widespread use this year after suffering a terrible outbreak with 2,341
cases in 2005.
The SA 14-14-2 vaccine has become more widely available in recent years.
It has been imported and licensed for use in South Korea (since 2001) and
in Nepal. Use of the vaccine in these sites has provided excellent
efficacy and safety data. In June 2005, WHO's Global Advisory Committee on
Vaccine Safety reviewed data on the vaccine and acknowledged its excellent
safety and efficacy profile (World Health Organization. Global Advisory
Committee on Vaccine Safety, 9-10 June 2005. Weekly Epidemiological
Record. 2005;80(28):242-243). Its efficacy has been estimated to be
between 80 to 99 percent following a single dose. Last year The Lancet
reported results of a trial in Nepal that showed a single dose of SA
14-14-2 JE vaccine was 99 percent effective after 1 year in protecting
children from JE. Several studies have shown that side effects after
immunization with SA 14-14-2 JE vaccine are rare. Where side effects have
been noted, the most common ones are fever and local reactions such as
tenderness, redness, and swelling.
The only other currently available JE vaccine is the inactivated mouse
brain-derived vaccine used by Japan, Taiwan, and Vietnam, among other
countries. In India, the inactivated mouse-brain derived vaccine produced
by CRI, Kasauli, is used, but supply of this vaccine is limited. Only
about 500,000 doses are produced annually-about enough to vaccinate a
maximum of 250,000 children. The dosing schedule for this vaccine is
complex, with several doses required to achieve protection, and there are
issues with compliance and affordability with this vaccine. Nonetheless,
it will be important to continue JE immunization in those Indian states
that have already been protecting infants and children previously with JE
vaccine, even as India expands its JE coverage to include other states at
risk of JE.
Regarding the question of prequalification of the SA 14-14-2 vaccine, the
process of WHO's prequalification of a vaccine involves evaluation to
determine the acceptability of a vaccine to enable procurement by United
Nations (UN) agencies such as the United Nations Children's Fund (UNICEF).
WHO prequalifies vaccines because international procurement agencies do
not have a national regulatory body to advise them on the appropriateness
of a vaccine. At the national level, this responsibility lies with the
National Control Authority. WHO does not approve vaccines; it only
prequalifies them for purchase after careful evaluation related to safety,
efficacy, and production. There are currently no prequalified JE vaccines,
as no manufacturers have applied for prequalification. The inactivated
vaccine, which has been used widely, was never prequalified by WHO.
Currently, a file is in preparation for submission to WHO for
prequalification of the SA 14-14-2 JE vaccine.
Concerning JE vaccines under development, two are in advanced stages of
clinical development:
* ChimeriVax-JE
The ChimeriVax-JE (Acambis) vaccine is not yet available and not licensed
anywhere, but trial results so far look promising. Acambis has a
collaboration with Bharat Biotech in India. The vaccine is a live,
recombinant JE vaccine (which uses Yellow Fever 17D as its backbone
combined with the SA 14-14-2 vaccine virus. Phase III clinical trials are
underway in adults in Australia, but no pediatric trials have begun. Plans
are underway to initiate trials in children and infants in India.
* Intercell's JE vaccine
An inactivated, vero-cell derived JE vaccine is under development by
Intercell but is currently not licensed or available. It is undergoing
adult Phase III clinical trials in Europe, the United States, and
elsewhere, but no pediatric trials have begun. This vaccine also looks
very promising. Intercell has a collaboration with Biological E in India
to develop this vaccine. Plans are underway to initiate trials in children
and infants in India.
No other JE vaccines are currently available and, as yet, none of the new
JE vaccines being developed has been licensed for infants and children,
the primary group to be targeted for this vaccine in endemic settings.
Information from clinical trials in this age range will be important
before the vaccines under development can be considered for use in JE
immunization programs.
With regards to the availability of the live SA 14-14-2 vaccine from
China, the vaccine is produced by several producers in the country but
currently only the Chengdu Institute of Biological Products (CDIBP) has
authority to export outside of China. Supply from this manufacturer is
being increased and pricing for public sector lower income countries (GNP
> 1000USD) is available to facilitate access.
It is hoped that the range of JE vaccine options and supply will expand in
the future. PATH is closely following the progress in development of these
vaccines. An encouraging sign is that countries like India, South Korea,
Nepal, and others are taking steps to protect their populations by
licensing JE vaccines at country level. As JE immunization plans move into
action, even more infants and children will be spared from the impact of
this devastating disease.
I hope this update about JE vaccine options is useful.
Julie Jacobson, MD
Director, PATH's Japanese Encephalitis Project
PATH
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