title: National surveillance of invasive pneumococcal diseases in Taiwan, 2008-2012: differential temporal emergence of serotype 19A.
abstract: BACKGROUND
  Serotype replacement after the introduction of seven-valent pneumococcal conjugate vaccine (PCV7) and the future availability of multivalent PCVs prompted the listing of invasive pneumococcal disease (IPD) as a notifiable disease in Taiwan in October 2007. Here, we report the national surveillance results.
  
  
  METHODS
  The study population comprised the whole nation of Taiwan from 2008 to 2012. Restricting to cases with viable isolates, we calculated the incidence, case fatality ratio, prevalence of serotype 19A, and percentage of vaccine preventable IPD.
  
  
  RESULTS
  3659 cases of IPD were identified yielding an incidence of 3.2 per 100,000 population; the highest incidence was among children aged 2-4 years (21.1 per 100,000 population). The case fatality ratio was 9.2% and the highest ratio was among adults aged ≥75 years (19.0%). The percentage of PCV7 preventable IPD decreased for all age groups, especially sharply among children aged 2-4 years, from 65.8% in 2008 to 12.9% in 2012. The prevalence of serotype 19A increased from 5.5% in 2008 to 25.3% in 2012 among all Streptococcus pneumoniae, displaying a differential temporal emergence among different age groups. Serotype 19A became the most prevalent serotype among children aged <2 years in 2009, children aged 2-4 and 5-17 years in 2010, and adults aged 18-49 years in 2012.
  
  
  CONCLUSIONS
  The incidence of IPD fluctuated during the study period, with ongoing decrease due to PCV7 vaccine serotypes and increase due to non-vaccine serotypes. Serotype 19A became the most prevalent serotype in 2010 among all S. pneumoniae.
authors.affiliation: Centers for Disease Control, Taipei, Taiwan; Center of General Education, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan. Electronic address: cschiang10@cdc.gov.tw.
authors.forename: Chuen-Sheue
authors.initials: CS
authors.lastname: Chiang
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Ying-Yan
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Shr-Fong
authors.initials: SF
authors.lastname: Jiang
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Ding-Ping
authors.initials: DP
authors.lastname: Liu
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Pei-Hsiu
authors.initials: PH
authors.lastname: Kao
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Hwa-Jen
authors.initials: HJ
authors.lastname: Teng
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Tsung-Lin
authors.initials: TL
authors.lastname: Kuo
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Shu-Man
authors.initials: SM
authors.lastname: Yao
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Lei-Ron
authors.initials: LR
authors.lastname: Tseng
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Yu-Lan
authors.initials: YL
authors.lastname: Wang
authors.affiliation: Centers for Disease Control, Taipei, Taiwan.
authors.forename: Ho-Sheng
authors.initials: HS
authors.lastname: Wu
authors.affiliation: Centers for Disease Control, Taipei, Taiwan; Department of Internal Medicine, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
authors.affiliation: Ministry of Health and Welfare, Taipei, Taiwan; Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan. Electronic address: alinpid@gmail.com.
authors.forename: Tzou-Yien
authors.initials: TY
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D018563:Disease Notification; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000401:mortality; D018571:Sentinel Surveillance; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult
keywords: Invasive pneumococcal disease; National surveillance; Serotype 19A; Streptococcus pneumoniae; Taiwan