Incidence of Radiologically-Confirmed Pneumonia and Haemophilus influenzae Type b Carriage before Haemophilus influenzae Type b Conjugate Vaccine Introduction in Central Vietnam

Abstract

To determine the incidence of radiologically-confirmed pneumonia (RCP) and Haemophilus influenzae type b (Hib) carriage in central Vietnam as a baseline data before Hib conjugate vaccine introduction. In the context of ongoing population-based prospective, hospitalized acute respiratory infection surveillance study, a cross-sectional Hib carriage study was conducted among 1000 children < 5 years of age livingin NhaTrang, Vietnam in June 2010, 1 month before the nationwide introduction of Hib conjugate vaccine in Vietnam. The incidence of RCP hospitalizations among children < 5 years of age was 3.3 per 1000 children. The highest incidence was observed among children 12-23 month age group (8.3 per 1000). Haemophilus influenzae carriage was detected in 37% of the children and Hib carriage rate was 3%. Eighty-two percent of the Haemophilus influenzae had TEM β-lactamase resistance gene. The presence of 6 or more family members was associated with an increased rate of Hib carriage (P = .04). Incidence of RCP and Hib carriage in this cross-sectional survey are lower compared with other studies. Continued surveillance for invasive Hib disease and sequential Hib carriage surveys are needed to support future assessments of the impact of Hib conjugate vaccine in Vietnam.