Overview And Epidemiology
- Mosquito-borne flavivirus causing acute encephalitis syndrome.
- Case fatality rate averages 30%.
- Permanent neuropsychiatric sequelae seen in 30-50% survivors.
- Vectors include Culex vishnui subgroup, primarily Culex tritaeniorhynchus.
- Amplifying hosts include pigs and wading birds.
- Humans act as incidental dead-end hosts.
- Highly endemic in 355 districts across 24 Indian states.
Vaccines Available In India
| Vaccine Type | Strain | Commercial Brand | Nature |
|---|
| Live-attenuated | SA 14-14-2 | Chengdu Institute | Lyophilized powder |
| Inactivated cell culture | SA 14-14-2 | JEEV | Liquid ready-to-use |
| Inactivated Vero cell | Kolar 821564XY | JENVAC | Liquid ready-to-use |
Immunization Schedule And Dosage
Live-Attenuated SA 14-14-2 Vaccine
- Minimum age of administration is 8 months.
- Dose measures 0.5 mL given subcutaneously.
- Two-dose schedule recommended in endemic districts.
- First dose given at 9 months alongside measles and rubella vaccine.
- Second dose given at 16-18 months alongside diphtheria, tetanus, and pertussis booster.
Inactivated JEEV Vaccine
- Minimum age of administration is 1 year.
- Administered intramuscularly.
- Dose for children 1 to 3 years measures 3 µg in 0.25 mL.
- Dose for children >3 years and adults measures 6 µg in 0.5 mL.
- Primary schedule includes two doses on days 0 and 28.
- Need for booster doses remains undetermined.
Inactivated JENVAC Vaccine
- Minimum age of administration is 1 year.
- Administered intramuscularly.
- Dose measures 0.5 mL.
- Primary schedule includes two doses at 4-week intervals.
- Need for booster doses remains undetermined.
Recommendations For Use
- Routine vaccination indicated only for individuals residing in endemic districts.
- Both rural and urban children within endemic districts require vaccination.
- Recommended for travelers to endemic areas planning >4 weeks stay in rural zones during transmission season.
- Catch-up vaccination indicated for susceptible children up to 15 years during campaigns ahead of anticipated outbreaks.
- Not recommended for use as outbreak response vaccine.
Adverse Effects And Contraindications
- Common minor reactions include transient fever (5-10%), local reactions, rash, and irritability (1-3%).
- Contraindicated in cases of severe allergic reaction to previous dose or vaccine component.
- Live-attenuated vaccine contraindicated in immunocompromised patients and their household contacts.
- Pregnancy considered precaution; vaccination deferred unless travel risk outweighs fetal risk.
- Concomitant administration with other childhood vaccines found safe and immunogenic.
