Evaluation strategies for measuring pneumococcal conjugate vaccine impact in low-resource settings.

von Mollendorf, Claire; Lim, Ruth; Choummanivong, Molina; Sychareun, Vanphanom; Vilivong, Keoudomphone; Lai, Jana YR; Chan, Jocelyn; Dunne, Eileen M; Phommachanh, Sysavanh; Moore, Kerryn A; +13 more... Ortika, Belinda D; Gray, Amy; Weaver, Rupert; Mayxay, Mayfong; Phetsouvanh, Rattanaphone; Datta, Siddhartha S; Fox, Kimberley; Newton, Paul N; Mulholland, Kim E; Nguyen, Cattram D; Dance, David AB; Satzke, Catherine; Russell, Fiona M; (2021) Evaluation strategies for measuring pneumococcal conjugate vaccine impact in low-resource settings. Expert Review of Vaccines, 21 (8). pp. 1137-1145. ISSN 1476-0584 DOI: https://doi.org/10.1080/14760584.2021.1965474

Abstract

OBJECTIVES: Pneumococcal conjugate vaccines (PCVs) are effective in reducing pneumococcal disease. We measured 13-valent PCV (PCV13) effect on different pneumococcal outcomes using diverse studies in Lao People's Democratic Republic. METHODS: Studies included: pre-PCV13 population-based record review of hospitalized childhood pneumonia cases; acute respiratory infection (ARI) study post-PCV13 to demonstrate effectiveness (VE) against hypoxic pneumonia; invasive pneumococcal disease (IPD) surveillance in all ages (2004-2018); carriage studies in children hospitalized with ARI (2013-2019); community carriage surveys pre- and post-PCV13. RESULTS: Annual pneumonia incidence rate in children pre-PCV13 was 1,530 (95% confidence interval [CI] 1,477-1,584) per 100,000. Adjusted VE against hypoxic pneumonia was 37% (95% CI 6-57%). For IPD, 85% (11/13) of cases were due to vaccine-types pre-PCV13, and 43% (3/7) post-PCV13 in children aged <5 years; for ≥5 years, 61% (27/44) and 42% (17/40), respectively. For ARI cases, adjusted VE for vaccine-type carriage was 39% (95% CI 4-60) in <5 year olds; slightly higher than community surveys (23% [95% CI 4-39%] in 12-23 month olds). CONCLUSIONS: Despite limited baseline data, we found evidence of PCV13 impact on disease and carriage. Our approach could be used in similar settings to augment existing WHO PCV evaluation guidelines.