摘要:Despite effective vaccines, diphtheria (D) resurged recently in the former socialistic block, and tetanus (T) still occurs in less privileged countries. We studied the antibody persistence for D and T in Indian pre-school children who had received four doses of DTP vaccine and subsequently, the response to a booster dose. Anti-D and anti-T IgG antibodies prior to and one month after a DT vaccine were measured by ELISA in 223 healthy children of 4-6 years who had previously received four doses of the triple vaccine. Adverse reactions were monitored for one month. While 30% and 14% of subjects were susceptible to D and T, respectively, 98% and 100% of them attained seroprotection post-vaccination. Both responses were significant. Local, but not systemic reactions except fever were rather common. A high proportion of the Indian pre-school population is susceptible to D and T, despite of receiving four doses. The current policy of giving the fifth dose at this age is appropriate.