Background: Children hospitalized with culture-confirmed pulmonary tuberculosis (PTB) frequently present with acute symptoms, possibly because of superimposed pneumococcal pneumonia. We undertook a time-series analysis to determine whether routine immunization of children with pneumococcal conjugate vaccine (PCV) was temporally associated with changes in the incidence of hospitalization for PTB in South African children.
Methods: PCV was introduced in the South African public immunization program in April 2009, with coverage for the third dose of PCV of 10%, 64% and 89% in 2009, 2010 and 2011, respectively. Quarterly incidence rate ratios (IRRs) for culture-confirmed PTB were reported and compared between the pre-PCV era (2005-2008), the transitional-PCV era (2009-2010) and the established-PCV era (2011-2012), stratified by age and HIV status.
Results: Overall, the quarterly IRR within the pre-PCV period was 0.918 (P < 0.01) for all age-groups combined and IRR 0.919 (P < 0.01) in HIV-infected children. In infants, the quarterly IRR was 0.888 (P < 0.001) within the pre-PCV era, 0.937 (P = 0.360) within the transitional and 1.26 (P = 0.014) within the established-PCV era. In HIV-infected infants, the quarterly IRR was 0.872 (P < 0.001) within the pre-PCV era, 0.877 (P = 0.263) within the transitional and 0.975 (P = 0.886) within the established-PCV era. Comparing the pre-PCV era with established-PCV era, there was no additional effect on the incidence of hospitalization for PTB in all age groups.
Conclusions: The incidence of hospitalization for PTB declined significantly before the implementation of PCV and further declines in the PCV era could not be attributed to childhood immunization with PCV.