Specific antibody deficiency in children with chronic wet cough

The prevalence and clinical significance of specific polysaccharide antibody deficiency (SAD) in children are poorly understood. The authors sought to determine the prevalence of SAD in children with chronic wet cough, through a retrospective study of all children with chronic wet cough attending our tertiary respiratory clinic over a 12-month period. Antibody levels to 13 pneumococcal serotypes were measured following vaccination with the unconjugated pneumococcal polysaccharide vaccine, Pneumovax II, and clinical data were reviewed. Twenty-four children over 2 years of age with chronic wet cough were vaccinated. Fourteen (58%) failed to mount an adequate antibody response, consistent with SAD. Children with SAD were more likely than children with normal antibody responses to require intravenous antibiotics (p=0.035) and to have abnormal chest radiographs (p=0.029). The authors conclude that SAD is present in a significant number of children with chronic wet cough. The clinical significance and long-term outcome of SAD warrant further investigation in prospective studies.