doi:10.1038/nindia.2015.37 Published online 23 March 2015
An indigenous Japanese Encephalitis (JE) vaccine JENVAC could be universally active against the mosquito-bred brain inflaming virus of different geographic or genetic origins, claims a recently published phase 2/3 trials report on the vaccine1.
In October 2013, when India's former health minister Ghulam Nabi Azad launched Bharat Biotech's JENVAC, the vaccine was not approved for use in children. However now, through these trials, Bharat Biotech and researchers from the National Institute for Virology report that JENVAC could be safe to use both in adults as well as in children.
These two-year trials were conducted in over 600 patients at 9 sites in India — 3 each in coastal Andhra Pradesh and Hyderabad and 1 each in Jaipur, Kolkata, and Mysore. Between June and November of 2011, the researchers gave JENVAC to 450 patients, ranging from 1-50 years of age. The rest of the patients were only adults, who were given a single dose of SA-14-14-2, another JE vaccine that is not yet approved for use in children.
With a single dose, the authors report, JENVAC keeps the JE virus at bay. The researchers found protective antibodies in patients even after a year of vaccination. When they gave a booster dose one month after the first shot, they found JENVAC’s efficacy only improved, but did not wane. With minimal side effects, the authors show that JENVAC is better than SA-14-14-2, though only slightly.
The researchers also found that sera collected from JENVAC-protected patients nullified other JE virus strains. These strains of viruses were reported to have caused JE in different countries at distinct time periods in the past. This finding led the researchers to claim that JENVAC could be universally active against JE virus of distinct origins and genetic make up.
“JENVAC produced protective levels of antibodies that were better than that of the comparator vaccine against all the major genotypes of the virus tested”, says Nagendra R. Hegde, the corresponding author. JENVAC can stay active in very high temperatures making it easy for health care practitioners to transport the vaccine to remote areas.
Scott Halstead at the Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, USA, feels that the trials’ results are skewed by the comparison of JENVAC, a killed vaccine, with SA-14-14-2, a live attenuated vaccine. He says, the researchers should have compared the response of their vaccine to that to the Vero-based JE vaccine produced globally.
However, he feels that JENVAC is a promising vaccine, though not really better than other available vaccines.
1. Singh, A. et al. A Japanese encephalitis vaccine from India induces durable and cross-protective immunity against temporally and spatially wide-ranging global field strains. J. Infect. Dis. (2015) doi: 10.1093/infdis/jiv023