ABSTRACT
OBJECTIVE: The effectiveness of Haemophilus influenzae type b (Hib) vaccine in preventing severe pneumonia in Asian children has been questioned, and many large Asian countries yet to introduce Hib conjugate vaccine in immunization programs. The primary objective of this study was to assess Hib conjugate vaccine effectiveness (VE) on radiologically-confirmed pneumonia in children born after introduction of Hib conjugate vaccine in Pakistan. STUDY DESIGN: A matched case-control study enrolled cases of radiologically-confirmed pneumonia in several hospitals serving low-income populations during 2009-2011. Cases were matched by age and season with 3 hospital and 5 neighborhood controls. Pneumonia was diagnosed using standardized World Health Organization criteria for chest radiograph interpretation. Matched OR were estimated for VE. RESULTS: A total of 1027 children with radiologically-confirmed pneumonia were enrolled; 975 cases, 2925 hospital controls, and 4875 neighborhood controls were analyzed. The coverage for 3 doses of diphtheria-tetanus-pertussis-hepatitis B-Hib conjugate vaccine was 13.7%, 18%, and 22.7% in cases, hospital controls and neighborhood controls, respectively. Estimated Hib VE for radiologically-confirmed pneumonia was 62% with 3 doses of vaccine using hospital controls and 70% using neighborhood controls. CONCLUSIONS: Hib conjugate vaccine prevented a significant fraction of radiologically-confirmed pneumonia in children in Pakistan. Maximizing impact on child survival needs improved immunization coverage.
Subject(s)
Haemophilus Infections/prevention & control , Haemophilus Vaccines/administration & dosage , Haemophilus influenzae type b/immunology , Immunization Programs , Pneumonia, Bacterial/prevention & control , Case-Control Studies , Child , Child, Preschool , Female , Haemophilus Infections/diagnostic imaging , Haemophilus Infections/immunology , Humans , Infant , Male , Pakistan/epidemiology , Pneumonia, Bacterial/diagnostic imaging , Pneumonia, Bacterial/immunology , Poverty , Radiography , Vaccines, Conjugate/administration & dosageABSTRACT
OBJECTIVE: Significant neurodevelopmental sequelae are known to occur after acute bacterial meningitis (ABM). This study determined the burden of such sequelae in Pakistani children aged <5 years to guide policies for Haemophilus influenzae type b (Hib) and pneumococcal vaccination. STUDY DESIGN: Cases of ABM were recruited from hospital-based surveillance and assigned to 1 of 3 etiologic groups (Hib, Streptococcus pneumoniae, or unknown etiology). Two age-matched controls were recruited for each case. Six months after enrollment, each case underwent neurologic history and examination, neurodevelopmental evaluation, and neurophysiological hearing test. Controls were assessed in parallel. RESULTS: Of 188 cases, 64 (34%) died. Mortality among subgroups were 7 (27%), 14 (28%), and 43 (39%) for Hib, Streptococcus pneumoniae, and unknown etiology, respectively. Eighty cases and 160 controls completed the assessments. Sequelae among cases included developmental delay (37%), motor deficit (31%), hearing impairment (18.5%), epilepsy (14%), and vision impairment (14%). Sequelae were higher after pneumococcal meningitis (19, 73%) compared with Hib meningitis (8, 53%). Compared with controls, cases were at significantly higher risk for all sequelae (P < .0001). CONCLUSIONS: ABM causes a substantial long-term burden of poor neurodevelopmental outcomes. Hib and pneumococcal vaccines are very effective interventions to prevent meningitis and its disabling sequelae.