Soon the National Institute of Virology (NIV) at Pune will be conducting clinical trials of the Chinese made SA14-14-2 vaccine for Japanese Encephalitis (JE) to supplement the data that have collected over the Indian strain of the virus. KEM Hospital, Mumbai will conduct the trials in collaboration with NIV and it would test the immunogenicity of the vaccine.
India had imported 10 lakh doses of live attenuated JE vaccine SA-14/14/2 from Chengdu Institute of Biological Products, Chengdu, China during last year. The Union Health Ministry is now in the processing of administering the Chinese vaccine to prevent an outbreak of JE in various disease prone states since June, the time of southwest monsoon in India.
JE is a viral disease, which normally affects children below 15, and has no effective cure so far. The virus is transmitted to humans through pigs and the disease is prevalent mainly in areas with a large number of piggeries. The outbreak of 6,500 JE cases claimed the lives of nearly 2,000 people, mostly children, in Nepal and India during last year. The Indian state of Uttar Pradesh was particularly hard hit, leading the Government of India to swiftly develop a strategy to prevent such outbreaks, especially during the rainy season.
China had over a 15-year period vaccinated more than 200 million children with the vaccine made from active but weakened virus. The Chinese vaccine is proven for its safety, efficacy, affordability and easy to administer in large campaigns, as only one dose is required instead of three doses. Two other vaccines are used in China, though they are not yet commercially available on the international market.
A cell culture derived, inactivated vaccine grown on primary hamster kidney cells was produced in 1967, and millions of doses are used each year in China. The vaccine is inexpensive (about 2-3 US cents per dose), but it has a relatively low seroconversion after two doses (only about 60%). A booster given in the second year increases seroconversion to 93%.
In China, the inactivated vaccine slowly is being replaced by a live, attenuated vaccine (SA14-14-2). Licensed in China since 1988, it has been given to over 200 million children. A single dose is 80% effective, increasing to 97.5% after two doses given one year apart. Protection lasts for at least 5 years. This vaccine has an excellent safety record, with no serious complications reported so far. Additional work in Nepal has shown this vaccine to have an efficacy of 99% within one week of administration.
Several other vaccines are being developed to battle JE. Many show promise, but all are several years away from production.
Scientists at the National Institute of Immunology (NII) New Delhi have developed a vero cell based JE vaccine and the strain was transferred to Panacea Biotec, New Delhi for commercialisation.
The Union Minister for Health Dr.Anbumani Ramadoss a few months ago informed the Rajya Sabha that the company has scaled up the candidate vaccine to an appropriate level and is now on the process of completing pre-clinical toxicology studies. It is expected that after completion of clinical trials and depending on the feedback, the vaccine could be introduced in two to three years. Many other Indian vaccine manufacturers are also exploring to develop vaccines to prevent this disease, the minister said.