Effectiveness of Varicella Vaccination Program in Preventing Laboratory-Confirmed Cases in Children in Seoul, Korea.
A universal one-dose varicella vaccination program was introduced in 2005 in Republic of Korea. However, the incidence of varicella in Korea has tripled over the last decade. We conducted a community based 1:1 matched case-control study to assess the effectiveness of one MAV strain-based vaccine and three Oka strain-based vaccines licensed for use in Korea. All cases were children in Seoul, Korea with varicella who were reported to the National Notifiable Disease Surveillance System in Seoul during 2013. The controls were age-matched children with mumps or scarlet fever but no history of varicella. We included 537 cases and 537 controls. The overall effectiveness of one dose of varicella vaccination was 13% (95% confidence interval [CI], -17.3-35.6). Of the four licensed varicella vaccines, only one was highly effective (88.9%; 95% CI, 52.1-97.4). The vaccine effectiveness for the other vaccines were 71.4% (95% CI, -37.5-94.1), -5% (95% CI, -61.9-31.9), and -100% (95% CI, -700-50.0). The overall effectiveness of vaccination was 75.8% (95% CI, 22.8-92.4) in the first year after vaccination and decreased thereafter; the effectiveness became -7.2% (95% CI, -130.9-59.2) in the fourth year after vaccination. Further studies are warranted to investigate reduced effectiveness of varicella vaccines in Korea.
Seoul Center for Infectious Disease Control, Seoul, Korea.|Department of Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, Korea.
Young Hwa
http://orcid.org/0000-0003-2073-993X
YH
Lee
Seoul Center for Infectious Disease Control, Seoul, Korea.|Department of Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, Korea.
Young June
http://orcid.org/0000-0003-2733-0715
YJ
Choe
Seoul Center for Infectious Disease Control, Seoul, Korea.|Department of Epidemiology, Graduate School of Public Health, Seoul National University, Seoul, Korea.
Sung Il
http://orcid.org/0000-0003-4085-1494
SI
Cho
Seoul Center for Infectious Disease Control, Seoul, Korea.|Institute of Endemic Disease, Seoul National University College of Medicine, Seoul, Korea.
Cho Ryok
http://orcid.org/0000-0002-9212-8292
CR
Kang
Seoul Center for Infectious Disease Control, Seoul, Korea.|Division of Infectious Diseases, Seoul National University Boramae Medical Center, Seoul, Korea.
Ji Hwan
http://orcid.org/0000-0002-7628-1182
JH
Bang
Seoul Center for Infectious Disease Control, Seoul, Korea.|Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea. mdohmd@snu.ac.kr.
Myoung Don
http://orcid.org/0000-0002-2344-7695
MD
Oh
Seoul Center for Infectious Disease Control, Seoul, Korea.|Department of Family Medicine, Seoul National University College of Medicine, Seoul, Korea.
Jong Koo
http://orcid.org/0000-0003-4833-1178
JK
Lee
D016022:Case-Control Studies; D002644:Chickenpox / Q000517:prevention & control*; D019433:Chickenpox Vaccine / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D016015:Logistic Models; D008297:Male; D056910:Republic of Korea; D016896:Treatment Outcome
D019433:Chickenpox Vaccine
Case-Control Study; Chickenpox; Korea; Matched Case-Control Study; Vaccination; Varicella