Decline in pulmonary TB hospitalizations among children not associated with PCV
Researchers in South Africa found a significant reduction in hospitalizations among children with culture-confirmed pulmonary tuberculosis prior to the introduction of a pneumococcal conjugate vaccine, or PCV, and further declines in hospitalizations after the vaccine was introduced could not be linked with immunization, they said.
“Hospitalization for [pulmonary tuberculosis (PTB)] in children frequently (43% to 77%) presents with an acute history cough ([less than] 7 days’ duration),” Vijay G. Mammen, MBBCh, MMed, FCPaed, from the department of pediatrics at the University of the Witwatersrand, South Africa, and colleagues wrote. “This acute presentation of PTB may be related to superimposed pneumococcal infection precipitating an acute hospitalization of pneumonia in children with underlying PTB. It is postulated that active TB may cause aberrations in immunity making children more susceptible to bacterial infections.”
In a previous study, Mammen and colleagues demonstrated a reduction in TB hospitalizations among children who were vaccinated with a 9-valent PCV.
The researchers then a conducted a retrospective study of PTB–related hospitalizations from 2005 to 2012 at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa, to determine whether routine infant PCV immunization affected incidence of hospitalizations for PTB in HIV–infected and uninfected children. The study comprised 950 children in three time periods: pre-PCV era (2005 to 2008), the transitional PCV era (2009 to 2010) and the established PCV era (2011 to 2012).
HIV prevalence during this study period was between 16% and 17% in adults and 2% and 3% in children, according to the researchers.
Data analysis showed no significant difference in hospitalization due to PTB in all age groups. Overall, the quarterly incidence rate ratio (IRR) during the pre-PCV era was 0.918 (P < .01) for all age groups combined and 0.919 (P < .01) for HIV–infected children. The quarterly IRR for infants in the pre-PVC period was 0.888 (P < .001), 0.937 (P = .360) in the transitional period and 1.26 (P = .014) in the established period. Among HIV–infected infants, the quarterly IIR was 0.872 (P < .001) in the pre-PCV era, 0.877 (P = .263) in the transitional era and 0.975 (P = .886) in the established era.
“Pneumococcus was the predominant invasive pathogen, isolated in 58 (47.2%) of 123 significant bloodstream pneumonia pathogens in the earlier study,” the researchers wrote. “The results of our study suggest a need to continue monitoring the impact of PCV on PTB hospitalization. However, our ability to find significant declines attributable to PCV immunization is likely to be undermined by the much lower incidence of culture-confirmed PTB compared to that which was observed during the PCV efficacy trial period.” – by Kate Sherrer