Pneumococcal conjugate vaccines and hospitalization of children for pneumonia: a time-series analysis, South Africa, 2006–2014

Among children younger than five years, Streptococcus pneumoniae is the leading cause of bacterial pneumonia and such pneumonia caused an estimated 411 000 deaths in 2010 and 335 000 deaths in 2015 globally. Although Africa has only 23% of the world’s children younger than five years, it accounts for approximately 43% of the deaths in this age group attributed to bacterial pneumonia. By June 2016, as part of the fight against bacterial pneumonia, pneumococcal conjugate vaccines were included in many national immunization programmes, including those of 24 low-income and 33 lower-middle-income countries.3 The public health impact of seven-, 10- or 13-valent pneumococcal conjugate vaccines against all-cause pneumonia has been investigated in several high-income countries and some middle-income Latin American countries. In these studies, the temporal reduction seen in all-cause pneumonia following childhood immunization with a pneumococcal conjugate vaccine has varied from 0 to 77%.4–9 In Malawi, the impact of a 13-valent vaccine (PCV13) on clinically diagnosed severe or very severe pneumonia has recently been evaluated. In this investigation, however, the study period began after introduction of the vaccine, ran for only 2.5 years and covered a time when only about 50% of the study population were estimated to be receiving all of the scheduled doses of the vaccine.10 In addition, there was no attempt to see if impact of the immunizations in Malawi was affected by human immunodeficiency virus (HIV) status. In the present study, we used data collected at a single hospital in the South African township of Soweto over an eight-year period centred on 2009 – the year a pneumococcal conjugate vaccine was first included in South Africa’s routine immunization programme. We used a time-series analysis and a Bayesian model to investigate the apparent impact of infant immunizations with pneumococcal conjugate vaccines on hospitalizations for pneumonia among HIV-uninfected and HIV-infected children younger than five years.