The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong: A 14-year population-based interrupted time series analysis. Issue 19 (6th May 2021)

• Record Type: Journal Article
• Authors: Yu, Qiuyan; Li, Xue; Fan, Min; Qiu, Hong; Wong, Angel Y.S.; Tian, Linwei; Chui, Celine S.L.; Li, Philip H.; Lau, Lauren K.W.; Chan, Esther W.; Goggins, William B.; Ip, Patrick; Lum, Terry Y.; Hung, Ivan F.N.; Cowling, Benjamin J.; Wong, Ian C.K.; Jit, Mark
• Is Part Of: Vaccine. Volume 39:Issue 19(2021)
• Page Start: 2628
• Page End: 2635
• Publication Date: 2021-05-06
• Subjects: Pneumococcal conjugate vaccines -- Interrupted time series analysis -- Herd immunity -- Population-based electronic health records -- All-cause pneumonia -- Serotype surveillance; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2021.03.090
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: Measuring the PCV effect using all-cause pneumonia is complex and multi-factorial. Assess the PCV immunisation programme with cost-effectiveness measurements. Monitor serotype replacement associated with vaccine introduction in real-time. Serotype surveillance system is imperative for PCV-related policy planning. Abstract: Background: Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK. Methods: In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis. Findings: Over the 14-year study period, a total of 587, 607 ACP episodes were identified among 357, 950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100, 000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932–0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904–0·9953) but not in younger age groups. Interpretation: There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring. Funding: Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).