Pre-discharge immunization among hospitalized Filipino children. Identifying opportunities to vaccinate eligible children is one way to boost rates of immunization especially in countries with low immunization coverage and where convalescence from infectious illness is a contraindication to vaccination. To determine the safety and immunogenicity of diphtheria-tetanus toxoid-pertussis and oral polio immunization, 210 convalescing infants and children and community controls, comparable image and nutritional status, were studied. Using the pertussis agglutination and poliovirus neutralization tests, quantitative serologic responses were compared in the two study groups. No significant differences in the incidence rates of febrile reactions (23% in controls; 28% in convalescents) of local reactions (92% in controls; 87% in convalescents) and of seroconversion (P greater than 0.05) were noted between the two groups. Our investigation suggests that infants and children convalescing from infectious illnesses can be safely and effectively vaccinated. This study further suggests that hospitalization provides an opportunity to vaccinate such children. 