Effect of single dose of SA 14-14-2 vaccine 1 year after immunisation in Nepalese children with Japanese encephalitis: a case-control study.
BACKGROUND
In July, 1999, a single dose of live-attenuated SA 14-14-2 Japanese encephalitis vaccine was given to children aged 1-15 years in the Terai region of Nepal. Cases of natural infection occurred almost immediately. Our aim was to assess the long-term protective effect of this vaccination.


METHODS
In 2000, this same population had a second seasonal exposure to the virus. We therefore did a case-control study to measure the prevalence of vaccination against Japanese encephalitis in 35 patients hospitalised for the disease 1 year after immunisation, and in age-sex matched village controls.


RESULTS
Of 35 children resident in Bardiya and Banke districts admitted to the Bheri Zonal Hospital with serologically confirmed Japanese encephalitis, only one had been vaccinated in 1999. In 430 age-sex matched village controls, 234 (54.4%) were vaccinated. We calculated a median unbiased estimate of the odds ratio of 0.0155, with lower and upper confidence limits of 0.0004 and 0.0986. The protective effect of vaccine after 12-15 months was 98.5% (CI 90.1-99.2%).


CONCLUSIONS
Our study provides evidence of sustained high protection afforded by one dose of live attenuated SA 14-14-2 vaccine in Nepalese children.
Ohrr
Heechoul
H
Department of Preventive Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea. ohrr@yumc.yonsei.ac.kr
Tandan
J B
JB
Sohn
Young Mo
YM
Shin
Sun Heang
SH
Pradhan
Durga Prasad
DP
Halstead
Scott B
SB
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004672:Encephalitis, Japanese / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage* / Q000276:immunology; D009390:Nepal / Q000453:epidemiology; D014613:Vaccines, Attenuated
D022321:Japanese Encephalitis Vaccines; D014613:Vaccines, Attenuated