Immunization coverage and immunity to diphtheria and tetanus among children in Hyderabad, India.

BACKGROUND

The Indian state of Andhra Pradesh accounted for 50% diphtheria and 3% tetanus cases reported globally during 2005. During 2003-2006, there was a rising trend of diphtheria in Hyderabad, the state capital, whereas there was no major change in trend of tetanus cases. We estimated coverage of diphtheria and tetanus vaccine among children aged <or= 6 years and immunity against these diseases among school children aged 7-17 years in Hyderabad.

METHODS

Using lot quality assurance sampling method, we surveyed children aged 12-23, 18-36 and 54-72 months to estimate coverage of three primary doses and first and second boosters of diphtheria and tetanus vaccine respectively. We conducted a sero-survey among children aged 7-17 years studying in randomly selected schools in Hyderabad. We tested sera for antibodies against diphtheria and tetanus.

RESULTS

Primary vaccination coverage was <80% in four of the seven circles of Hyderabad while booster coverage was <80% in entire city. Of the 2419 children sero-surveyed, 56% and 64% were immune to diphtheria and tetanus respectively (titre >or=0.1IU/ml). Booster coverage and immunity against these diseases was lower among Muslims.

CONCLUSIONS

It is necessary to improve booster coverage especially among Muslims. Vaccinating school children at school entry and periodic boosters thereafter will increase immunity among children.