Japanese encephalitis vaccination

Subject: Science and technology

Section: Health

Concept:

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.

Immunoglobulin G (IgG):

This is the most common antibody. It’s in blood and other body fluids, and protects against bacterial and viral infections. IgG can take time to form after an infection or immunization.

Japanese Encephalitis

Japanese Encephalitis – Acute Encephalitis Syndrome (JE-AES) is a serious health hazard. The disease mostly affects children and young adults which can lead to morbidity and mortality.
These infections particularly affect malnourished children of poor economic backgrounds.
Ministry of Health and Family Welfare is the nodal ministry.
The history of AES in India has paralleled with that of the Japanese encephalitis virus (JEV) since the first report in 1955 from Vellore, Tamil Nadu.
The first outbreak of JEV was reported in Bankura district, West Bengal in 1973.
Thereafter, sporadic cases of AES and outbreaks have been the leading cause of premature deaths due to the disease in India
Causes:
Viruses are the main causative agents in AES cases, although other sources such as bacteria, fungi, parasites, spirochetes, chemicals, toxins, and noninfectious agents have also been reported over the past few decades. It is not vaccine-preventable.
Japanese encephalitis virus (JEV) is the major cause of AES in India (ranging from 5%-35%).
Herpes simplex virus, Nipah virus, Zika virus, Influenza A virus, West Nile virus, Chandipura virus, mumps, measles, dengue, scrub typhus, S.pneumoniae are also found as causative agents for AES.

For notes on Types of Vaccines, refer – https://optimizeias.com/types-of-vaccine/