Epidemiology of Invasive Pneumococcal Disease in Taiwan, 2008-2013

Chia-Yu Hsu, En-Tzu Wang, Yu-Min Chou, Jer-Jea Yen.

2014 Vol.30 NO.22

Correspondence Author： Chia-Yu Hsu

Abstract：

       The pneumococcal polysaccharide vaccine(PPV)vaccination programfor elderly has implemented in Taiwansince October 2007, followed by pneumococcal conjunctive vaccine(PCV)vaccination programfor high-risk children <5 years old, beginning from July 2009. In this study,the domestic invasive pneumococcal disease(IPD)incidence, case-fatality rate, clinical syndromes, underlying disease cases, recurrent IPD and change of serotypesbetween 2008-2013are illustrated, and the current strategies ofIPD controlarefurther discussed.
       There were 4,439 identified IPD cases during these six years.Overall annual incidence was 3.2 cases per millionpopulations, and thehighest incidence was in 2-4 years age group (20.4 per million population). The average case fatality rate(CFR) was 18.2%, andthe CFR of cases in ≧75 years age group was 35.5%.
       Cases withunderlying disease accounted for 35.9%, and the most common disease was malignancy (12.7%). Pneumonia was the most commonclinical symptoms (61.0%) in IPD cases, followed by sepsis (47.9%). About 20% of the cases were complicated by pneumonia and sepsis. In addition, there were39 recurrent IPD cases (0.9%), with median age of 58 years, of which 72% had underlying disease, and 30%were re-infected by pneumococcus with the same serotypes.
       19A was the most prevalent serotype in IPD cases< 5 years old(accounting for 39.5%).Dominantserotypes in≧65 years age groups were 14,23F and 3 (totally accounted for 48.8%). It is worth noting that there have been significant increases in the rate of serotype 15 (15B was not included) since2012/2013, and serotype 15was not covered by any PCVs. In 2013, for example, coverage ratesof 7-valent conjugated pneumococcal vaccine (PCV7) and 13-valent conjugated pneumococcal vaccine (PCV13) were 21.4% and 79.5% in < 5 years age group.Coverage rate of 10-valent conjugated pneumococcal vaccine (PCV10) was consistent with that of PCV7 in < 5 years age group. In addition, the incidence of serotypes covered by PCV7/PCV10 in < 5 years age group declined from 11.06 per 100,000 persons in 2008 to 2.54 in 2013. The incidence of PCV13 serotypes dropped from 14.53 to 9.44,but non-PCV13 serotypes increased from 0.77 to 1.73.
       To protectpeople from IPD,surveillance of domestic IPD epidemiology and changes of serotypes and antimicrobial resistance in Streptococcus pneumoniaeshould be continued for assessing the effectiveness of pneumococcal vaccines and revising the prevention policies timely.