Invasive Pneumococcal Disease and Impact of 7- and 13-Valent Pneumococcal Conjugate Vaccines in Singapore Children Over 24 Years

Abstract

Background. Data on burden of invasive pneumococcal disease (IPD) are lacking from Southeast Asia. With the introduction of higher-valency pneumococcal conjugate vaccines (PCVs), we aim to assess the impact of PCV introduction into Singapore’s National Childhood Immunisation Schedule (NCIS) on IPD burden and serotype replacement. Methods. Using IPD surveillance data from a single center, we compared the incidence of IPD in children aged <17 years before and after introduction of the PCV into the NCIS (2000–2009, period 1; 2010–2023, period 2). Results. The overall incidence of IPD from 2000 to 2023 was 3.9 per 100 000 children. The decline in IPD incidence between periods 1 and 2 was greatest in children aged ≤2 years (13.3 to 4.7/100 000 children; incidence rate ratio 0.4 [95% CI, .3–.5]; P < .001). From period 1 to 2, IPD due to PCV7 serotypes declined from 136 (68.0%) to 37 (22.0%; odds ratio [OR], 0.1 [95% CI, .1–.2]; P < .001) and IPD by PCV13 serotypes from 161 (80.5%) to 118 (70.2%; OR 0.6 [95% CI, .4–.9]; P = .03). The proportion of children with IPD due to serotype 19A increased from 13 (6.5%) to 65 (38.7%) from period 1 to 2 (OR 9.1 [95% CI, 4.8–16.7]; P < .001). None of the children could be confirmed to have IPD due to specific PCV15–non-PCV13 serotypes or PCV20–non-PCV13 serotypes. Conclusions. Introduction of PCV into Singapore’s NCIS led to a substantial reduction in IPD burden in children aged ≤2 years. Serotype 19A continues to pose a challenge as a disease-causing serotype after PCV13 implementation in Singapore.