Pneumococcus nasopharyngeal carriage in children attending an academic hospital in Pretoria, South Africa, after the introduction of pneumococcal vaccine

BACKGROUND: In 2009, pneumococcal conjugate vaccine was introduced in South Africa. However, there are concerns that this could lead to an increase in colonisation of non-vaccine serotypes (serotype replacement). METHODS: In a cross-sectional study, 350 children aged 1 month to 14 years were enrolled at Dr George Mukhari Academic Hospital from December 2015 to April 2016. We assessed the prevalence of nasopharyngeal colonisation with pneumococcus and characterised the serotypes found. RESULTS: The median age of the cohort was 33.7 months (interquartile range 16.27-69.5 months), with 20% being < 1 year. A total of 21% of the children were diagnosed with pneumococcal-related conditions; among these, pneumonia was the most common condition. Less than half (43%) of the participants were fully immunised. Forty-six (13%) of the children were colonised with pneumococcus. Younger age was significantly associated with pneumococcal colonisation. Among those colonised with pneumococcus, 35% were fully immunised, 30% were partially immunised, 30% had an unknown immunisation status and 4% were unimmunised. Eight (17%) of the children who were colonised with pneumococcus had pneumococcal-related conditions. The commonest serotype identified was 6A/B. Overall, 2% of the cohort were colonised with vaccine-serotype pneumococcus. CONCLUSION: As a minority of children had evidence of nasopharyngeal colonisation with vaccine-serotype pneumococci, serotype replacement may be emerging in our population.