title: Identifying determinants of heterogeneous transmission dynamics of the Middle East respiratory syndrome (MERS) outbreak in the Republic of Korea, 2015: a retrospective epidemiological analysis.
abstract: OBJECTIVE
  To investigate the heterogeneous transmission patterns of Middle East respiratory syndrome (MERS) in the Republic of Korea, with a particular focus on epidemiological characteristics of superspreaders.
  
  
  METHODS
  Retrospective epidemiological analysis.
  
  
  METHODS
  Multiple healthcare facilities of secondary and tertiary care centres in an urban setting.
  
  
  METHODS
  A total of 185 laboratory-confirmed cases with partially known dates of illness onset and most likely sources of infection.
  
  
  METHODS
  Superspreaders were identified using the transmission tree. The reproduction number, that is, the average number of secondary cases produced by a single primary case, was estimated as a function of time and according to different types of hosts.
  
  
  RESULTS
  A total of five superspreaders were identified. The reproduction number throughout the course of the outbreak was estimated at 1.0 due to reconstruction of the transmission tree, while the variance of secondary cases generated by a primary case was 52.1. All of the superspreaders involved in this outbreak appeared to have generated a substantial number of contacts in multiple healthcare facilities (association: p<0.01), generating on average 4.0 (0.0-8.6) and 28.6 (0.0-63.9) secondary cases among patients who visited multiple healthcare facilities and others. The time-dependent reproduction numbers declined substantially below the value of 1 on and after 13 June 2015.
  
  
  CONCLUSIONS
  Superspreaders who visited multiple facilities drove the epidemic by generating a disproportionate number of secondary cases. Our findings underscore the need to limit the contacts in healthcare settings. Contact tracing efforts could assist early laboratory testing and diagnosis of suspected cases.
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan Graduate School of Medicine, Hokkaido University, Sapporo-shi, Hokkaido, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Endo
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan The Institute of Statistical Mathematics, Tokyo, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Saitoh
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan Graduate School of Medicine, Hokkaido University, Sapporo-shi, Hokkaido, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kinoshita
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Ueno
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Nakaoka
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan Graduate School of Medicine, Hokkaido University, Sapporo-shi, Hokkaido, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Miyamatsu
authors.affiliation: Infectious Disease Epidemiology team, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan CREST, Japan Science and Technology Agency, Saitama, Japan.
authors.forename: Yueping
authors.initials: Y
authors.lastname: Dong
authors.affiliation: School of Public Health, Georgia State University, Atlanta, Georgia, USA Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Chowell
authors.affiliation: CREST, Japan Science and Technology Agency, Saitama, Japan Graduate School of Medicine, Hokkaido University, Sapporo-shi, Hokkaido, Japan Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizumoto
mesh_terms: D016358:Contact Tracing; D018352:Coronavirus Infections / Q000453:epidemiology / Q000635:transmission*; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission; D004196:Disease Outbreaks; D006801:Humans; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies
keywords: EPIDEMIOLOGY