Acute Lower Respiratory Infection Among Bacille Calmette-Guérin (BCG)–Vaccinated Children

Abstract

OBJECTIVE: To determine whether Bacille Calmette-Guerin (BCG) vaccination is linked to the risk of acute lower respiratory infection (ALRI) among children <5 years of age. METHODS: Data from Macro International Demographic and Health Surveys and United Nations Children’s Fund Multiple Indicator Cluster Surveys were used to identify a primary cohort of 58 021 children in 19 countries (2005–2010) and a secondary cohort of 93 301 children in 18 countries (2000–2007). Information was collected by trained interviewers during home visits using standardized questionnaires, review of vaccination health cards, and measurement of health indicators. RESULTS: BCG vaccination was associated with a 17% to 37% risk reduction for suspected ALRI in both cohorts. The only vaccine or vitamin supplement to modify the effect of BCG was diphtheria-tetanus-pertussis (DTP; P < .001). The order in which the vaccines were first received was central to this phenomena (BCG before DTP, adjusted/propensity score–weighted relative risk [apRR]: 0.79, 95% confidence interval [CI]: 0.70–0.89; BCG with DTP, apRR: 0.82, 95% CI: 0.71–0.94; and BCG after DTP, apRR: 1.00, 95% CI: 0.87–1.13) but not number of DTP doses received. Other modifiers included vaccine strain used in immunization programs, chlorinating drinking water, using wood-burning fuel cook stoves, and owning livestock. CONCLUSIONS: Children vaccinated with BCG had a significantly lower risk of suspected ALRI. Clarification is needed as to whether this is due to reductions in the underlying risk of tuberculosis or ALRI per se.