title: A national cross-sectional study for poliovirus seroprevalence in the Republic of Korea in 2012: implication for deficiency in immunity to polio among middle-aged people.
abstract: BACKGROUND
  A worldwide poliomyelitis eradication program was initiated in 1988; however, strains of wild poliovirus (WPV) are still endemic in some countries. Until WPV transmission is eradicated globally, importation and outbreaks of WPV are alarming possibilities. This study is the first report to document the polio immunity after 2004, when an inactivated polio vaccine (IPV) was introduced in the Republic of Korea.
  
  
  METHODS
  A total of 745 serum samples from randomly selected patients ranging from 6 to 84 years of age were used for neutralization tests, performed in the World Health Organization polio national reference laboratory.
  
  
  RESULTS
  Among the 745 tested sera, 439 (58.9%) were seropositive and 19 (2.6%) were seronegative to all PV serotypes. In all age groups, PV3 showed the lowest level of seroprevalence, at 509 cases (68.3%), compared to 616 (82.7%) for PV1 and 685 (91.9%) for PV2. In the 6-10-year age group, which included IPV-immunized children, the highest seropositive rate was observed and the difference in seroprevalence between PV3 and other serotypes was the lowest compared to the other age groups immunized with oral PV vaccines (OPV). In addition, the seronegative rates of all three PV types in children aged 6-10 in this study were found to be lower than those in OPV-immunized children reported in a previous study from the Republic of Korea. Meanwhile, middle-aged subjects (41-60 years) had the lowest seroprevalence and geometric mean titer.
  
  
  CONCLUSIONS
  This study indicates a deficiency in immunity to PV in middle-aged individuals, and low seroprevalence to PV3 in all age groups. In addition, due to the ongoing risk of importing PV, middle-aged people should consider PV vaccination before visiting a PV-endemic country. Our findings provide data to assist those involved in deciding future national polio vaccination strategies for the maintenance of a polio-free status in Korea.
authors.affiliation: WHO Polio National Reference Laboratory, Division of Vaccine Research, Center for Infectious Diseases, Korea National Institutes of Health, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. limetree81@naver.com.|Department of Biology Graduate School, Kyung Hee University, Seoul, Dongdaemon-gu, 130-701, Republic of Korea. limetree81@naver.com.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: WHO Polio National Reference Laboratory, Division of Vaccine Research, Center for Infectious Diseases, Korea National Institutes of Health, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. 0117772624@hanmail.net.
authors.forename: Seoyeon
authors.initials: S
authors.lastname: Hwang
authors.affiliation: WHO Polio National Reference Laboratory, Division of Vaccine Research, Center for Infectious Diseases, Korea National Institutes of Health, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. somin6510@korea.kr.
authors.forename: Somin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Division of Vaccine Preventable Disease Control and Prevention, Center for Infectious Diseases Control, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. yhhodori@gmail.com.|Current Address: Division of HIV/AIDS and TB Control, Center for Infectious Diseases Control, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. yhhodori@gmail.com.
authors.forename: Yunhyung
authors.initials: Y
authors.lastname: Kwon
authors.affiliation: Division of Vaccine Preventable Disease Control and Prevention, Center for Infectious Diseases Control, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. ksmanse@korea.kr.
authors.forename: Kwangsook
authors.initials: K
authors.lastname: Park
authors.affiliation: Division of Vaccine Preventable Disease Control and Prevention, Center for Infectious Diseases Control, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. pahmun@hanmail.net.
authors.forename: Young Joon
authors.initials: YJ
authors.lastname: Park
authors.affiliation: Division of Vaccine Preventable Disease Control and Prevention, Center for Infectious Diseases Control, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. bgr824@naver.com.
authors.forename: Geun-Ryang
authors.initials: GR
authors.lastname: Bae
authors.affiliation: WHO Polio National Reference Laboratory, Division of Vaccine Research, Center for Infectious Diseases, Korea National Institutes of Health, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. epilsw@korea.kr.
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Biology Graduate School, Kyung Hee University, Seoul, Dongdaemon-gu, 130-701, Republic of Korea. ysjeong@khu.ac.kr.
authors.forename: Yong-Seok
authors.initials: YS
authors.lastname: Jeong
authors.affiliation: WHO Polio National Reference Laboratory, Division of Vaccine Research, Center for Infectious Diseases, Korea National Institutes of Health, Korea Centers for Disease Control and Prevention, Osong-eup, Cheongju, Chungcheongbuk-do, 363-951, Republic of Korea. jyhyeon1205@gmail.com.
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Hyeon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000276:immunology*; D002648:Child; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D011051:Poliomyelitis / Q000453:epidemiology / Q000517:prevention & control*; D017955:Poliovirus / Q000276:immunology*; D011054:Poliovirus Vaccine, Inactivated / Q000276:immunology* / Q000627:therapeutic use; D056910:Republic of Korea / Q000453:epidemiology; D016036:Seroepidemiologic Studies; D014944:World Health Organization; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D011054:Poliovirus Vaccine, Inactivated