Association between introduction of 13-valent pneumococcal conjugate vaccine and burden of hospitalized adult pneumococcal disease in Taiwan - a retrospective database study.

This study estimated the incidence rate (IR), case fatality rate (CFR), healthcare resource utilization, and costs of pneumococcal disease before and after the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) into Taiwan's childhood immunization programme (CIP) in 2015. Adults aged ≥18 years hospitalized with invasive pneumococcal disease (IPD) and pneumonia from 2011 to 2019 were identified from the Taiwan National Health Insurance Research Database. Baseline and trend of IRs were compared between pre-introduction (2011-2014) and post-introduction (2016-2019) of PCV13 using interrupted time series analyses and incidence rate ratio (IRR). Annual IRs for IPD and pneumonia ranged from 1.59 to 1.82 and 3.91 to 4.47 episodes per 100,000 person-years in the pre-PCV13 period, respectively. In the post-PCV13 period, they ranged from 1.23 to 1.37 and 3.20 to 3.95 episodes per 100,000 person-years, respectively. There was a significantly lower baseline IR in the post-PCV13 period for both IPD (IRR = 0.76; 95% confidence interval [CI]: [0.63, 0.93]) and pneumonia (IRR = 0.87; 95% CI: [0.77, 0.98]). However, a marginal increase in the trend of IR was observed during the post-PCV13 period for both IPD (IRR = 1.02; 95% CI: [1.00, 1.03]) and pneumonia (IRR = 1.02; 95% CI: [1.01, 1.03]). Estimated CFRs were lower in the post-PCV13 period for both diseases. The clinical burden remains substantial after the introduction of PCV13 into Taiwan's CIP.