Why in News?

• A recent study found no neutralising antibodies after Japanese encephalitis vaccination
• A small study involving 266 children, who had received two doses of a live, attenuated Japanese encephalitis vaccine SA-14-14-2 made in China, found very low levels of neutralising antibodies IgG at different time points after vaccination.
• Study did not measure cell-mediated immune responses (T-cell immune responses).
• Nearly 98% of the children who received the vaccine did not have any IgG antibodies against the virus.
• The results are in line with other studies conducted outside India, which too found a decline in neutralising antibody levels post-vaccination.
• Immunisation of children with the Chinese vaccine began in 2006 in 11 endemic regions, and became a part of the Universal Immunisation Programme in 181 endemic districts in 2011 first with a single dose and subsequently (2013) with two doses.
• Despite vaccination, there have been several outbreaks in the endemic regions, particularly in Gorakhpur district.
• The disease burden is highest in the Gorakhpur region of eastern Uttar Pradesh.

Jenvac:

• In contrast, a trial carried out using an inactivated vaccine-Jenvac, developed by Bharat Biotech in collaboration with National Institute of Virology(NIV), Pune using a virus strain collected in India, has found superior protection at the end of two years even with a single dose.
• Jenvac has been approved as a single-dose vaccine; two doses of Jenvac are used as part of the Universal Immunisation Programme.
• In the head-to-head comparison trial using Jenvac and the Chinese vaccine, the seroprotection at the end of one year and two years was 81.7% and 88.5% for Jenvac and just 47.9% and 68.3% for the Chinese vaccine, respectively.
• The trial also found significantly higher neutralising antibodies when children received two doses of Jenvac rather than two doses of the Chinese vaccine.