Vaccine Info

Jenvac Japanese Encephalitis Vaccine

Authored by
Last reviewed
August 16, 2021
Fact checked by
Robert Carlson, MD

JENVAC Description

JENVAC is a single dose inactivated Japanese Encephalitis (JE) Vaccine. This Vero cell-derived vaccine is prepared from an Indian strain (Kolar- 821564XY) of the JE virus. JENVAC has been developed in collaboration with the National Institute of Virology, India. It is a safe and highly effective vaccine that protects against all known strains of Japanese Encephalitis

JENVAC® is a safe and highly effective vaccine that protects against all the known strains of Japanese encephalitis.

JENVAC Indication

JENVAC® is a vaccine for Japanese Encephalitis, which is caused by the Japanese Encephalitis virus (JEV) and is the most important cause of viral encephalitis in Asia. JEV is a mosquito-borne flavivirus and belongs to the same genus as dengue, yellow fever, and West Nile viruses. JEV is transmitted to humans through bites from infected mosquitoes of the Culex species.

Most JEV infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections result in severe clinical illness. Severe disease is characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, paralysis and ultimately death.

The case-fatality rate can be as high as 30% among those with disease symptoms. Of those who survive, 20%–30% suffer permanent intellectual, behavioral or neurological sequelae such as paralysis, recurrent seizures or the inability to speak.

There is no antiviral treatment for patients with JE. Treatment is supportive to relieve symptoms and stabilize the patient.


Data of a 2-dose study shows that a single dose of JENVAC is sufficient to elicit the immune response as the subjects who received a single dose were 98.67% sero-protected and the 4-fold sero-conversion was at 93.14% for the ≥1 year to ≤50 years age group.

JENVAC vaccine is administered intramuscularly into the deltoid region of the upper arm for adults and the anterolateral region of the thigh for children. As per the IAP Recommended immunization schedule (2018-19), the JE vaccine should be administered as follows: at 12 months and 13 months.


Infants younger than 2 months should not be administered JE vaccine

People who have had a life-threatening allergic reaction to the JE vaccine or any ingredient in the vaccine

Have serious allergies of any kind

If the subject is pregnant

JENVAC Adverse Events

The most common adverse events noted were pain, swelling, or redness where the shot was given, headache and muscle aches (mostly in adults), and low fever (mostly in children). Serious side effects from the JE vaccine are very rare.

Japanese Encephalitis news can be found at Precision 

Clinical Trials

No clinical trials found