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Estimated severe pneumococcal disease cases and deaths before and after pneumococcal conjugate vaccine introduction in children younger than 5 years of age in South Africa

Thursday, 31st of August 2017

Full text is at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0179905

PLoS One. 2017 Jul 3;12(7):e0179905. doi: 10.1371/journal.pone.0179905. eCollection 2017.

Estimated severe pneumococcal disease cases and deaths before and after pneumococcal conjugate vaccine introduction in children younger than 5 years of age in South Africa

von Mollendorf C^1,2, Tempia S^3,4, von Gottberg A^1,5, Meiring S⁶, Quan V⁶, Feldman C^7,8, Cloete J⁹, Madhi SA^1,10, OBrien KL¹¹, Klugman KP¹², Whitney CG³, Cohen C^1,2.

Author information

1

Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, a division of the National Health Laboratory Service, Johannesburg, South Africa.

2

School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.

3

Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.

4

Influenza Program, Centers for Disease Control and Prevention, Pretoria, South Africa.

5

School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.

6

Division of Public Health Surveillance and Response, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa.

7

Department of Internal Medicine, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa.

8

Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.

9

Department of Paediatrics and Child Health, University of Pretoria, Steve Biko Academic Hospital, Pretoria, South Africa.

10

Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Johannesburg, South Africa.

11

Johns Hopkins Bloomberg School of Public Health, International Vaccine Access Center, Department of International Health, Baltimore, Maryland, United States of America.

12

Hubert School of Public Health, Emory University, Atlanta, Georgia, United States of America.

Abstract

INTRODUCTION:

Streptococcus pneumoniae is a leading cause of severe bacterial infections globally. A full understanding of the impact of pneumococcal conjugate vaccine (PCV) on pneumococcal disease burden, following its introduction in 2009 in South Africa, can support national policy on PCV use and assist with policy decisions elsewhere.

METHODS:

We developed a model to estimate the national burden of severe pneumococcal disease, i.e. disease requiring hospitalisation, pre- (2005-2008) and post-PCV introduction (2012-2013) in children aged 0-59 months in South Africa. We estimated case numbers for invasive pneumococcal disease using data from the national laboratory-based surveillance, adjusted for specimen-taking practices. We estimated non-bacteraemic pneumococcal pneumonia case numbers using vaccine probe study data. To estimate pneumococcal deaths, we applied observed case fatality ratios to estimated case numbers. Estimates were stratified by HIV status to account for the impact of PCV and HIV-related interventions. We assessed how different assumptions affected estimates using a sensitivity analysis. Bootstrapping created confidence intervals.

RESULTS:

In the pre-vaccine era, a total of approximately 107,600 (95% confidence interval [CI] 83,000-140,000) cases of severe hospitalised pneumococcal disease were estimated to have occurred annually. Following PCV introduction and the improvement in HIV interventions, 41,800 (95% CI 28,000-50,000) severe pneumococcal disease cases were estimated in 2012-2013, a rate reduction of 1,277 cases per 100,000 child-years. Approximately 5000 (95% CI 3000-6000) pneumococcal-related annual deaths were estimated in the pre-vaccine period and 1,900 (95% CI 1000-2500) in 2012-2013, a mortality rate difference of 61 per 100,000 child-years.

CONCLUSIONS:

While a large number of hospitalisations and deaths due to pneumococcal disease still occur among children 0-59 months in South Africa, we found a large reduction in this estimate that is temporally associated with PCV introduction. In HIV-infected individuals the scale-up of other interventions, such as improvements in HIV care, may have also contributed to the declines in pneumococcal burden.