Epidemiology of invasive bacterial infections in HIV-infected and HIV-uninfected children under 5 years of age in Soweto, South Africa between 1998 and 2005
Date
2018
Authors
Trenor, Siobhan Lindsay
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Abstract
Introduction
Invasive bacterial infections (IBI) cause significant morbidity and mortality in infants and young children, predominantly in low and middle-income countries. There are limited data on paediatric IBI, as well as the impact of pneumococcal conjugate vaccine (PCV) on the spectrum of IBI pathogens, in African countries with a high prevalence of HIV infection. We described the epidemiology of IBIs in a cohort of children <5 years of age in Soweto, South Africa.
Objectives
To estimate the incidence of IBI in children <5 years of age that participated in the 9-valent PCV (PCV9) efficacy trial, stratified by age, PCV9 vaccination status and HIV infection status, as well as to determine which pathogens are responsible for IBI among PCV9 vaccinated and unvaccinated, and HIV-infected and –uninfected hospitalised children.
Methods
A secondary data analysis was performed using a cohort of children enrolled into the PCV9 randomised control trial (RCT) conducted in Soweto from 1998-2005. During this RCT, 39 836 children were randomised to receive either PCV9 or placebo, and surveillance was conducted by study doctors in admission wards at Chris Hani Baragwanath Academic Hospital (CHBAH) to identify hospitalised participants. Incidence of IBI was calculated using person-time (with censoring occurring on each participant’s fifth birthday or date of death) and stratified by age group, sex, PCV9 vaccination status and HIV infection status. Risk factors for IBI were investigated using binomial logistic regression.
Results
A total of 395 cases of laboratory-confirmed IBI were included in the analysis. The incidence of all-cause IBI hospitalisations decreased with increasing age. PCV9 vaccination was associated with reductions in incidence of all-cause IBI hospitalisation (IRR=0.76; 95% confidence interval (CI) 0.61 to 0.93, p=0.006) which was predominantly due to the reductions in Streptococcus pneumoniae incidence (IRR=0.56; 95% CI 0.39 to 0.78, p<0.001). PCV9 vaccination was associated with a decrease in incidence of PCV9- and PCV9-related serotypes in HIV-infected (IRR=0.53; 95% CI, 0.20 to 0.85, p=0.005) and HIV-uninfected (IRR=0.44; 95% CI, 0.17 to 1.07, p=0.051) participants. PCV9 vaccination had no significant effect on the incidence of Haemophilus influenzae type b or Salmonella species infections, however, there was a trend towards higher incidence of infections due to Staphylococcus aureus, a trend towards decrease in incidence of Escherichia coli and a significant increase (IRR=3.50; 95% CI, 1.10 to 14.59, p=0.019) in Klebsiella species IBI in PCV9 vaccinated children.
Conclusion
PCV9 vaccination was effective in reducing incidence of IBI hospitalisation in HIV-infected children through significant reductions in S. pneumoniae incidence. HIV-infected participants and those that did not receive PCV9 were at increased risk for IBI hospitalisation. Our results show that trends in other IBI causative pathogens (specifically Staphylococcus aureus and Klebsiella species) should be monitored in the post-PCV era.
Description
A research report submitted to the School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Epidemiology and Biostatistics.
Johannesburg, 2018.
Keywords
Invasive Bacterial Infections