Sero protection of DPT containing vaccine in congenital heart disease: A cross sectional study

Title: Seroprotection of Diphtheria, Pertussis and Tetanus (DPT) containing vaccine in children with Congenital Heart Disease: A Cross-Sectional study Aim: To determine the seroprotection of DPT-containing vaccine administered as per the National Immunisation Schedule in children with Congenital Heart Disease

Primary Objective: To compare the proportion of children with Congenital Heart Disease and those without congenital heart disease having seroprotective antibody titers against Diphtheria, 4-6 weeks after receiving 1st booster of DPT vaccine at 16-24 months. Secondary Objective i. To compare the proportion of children with and without congenital heart disease having seroprotective antibody titers against Pertussis, 4-6 weeks after receiving 1st booster of DPT at 16-24 months ii. To compare the proportion of children with and without congenital heart disease having seroprotective antibody titers against Tetanus, 4-6 weeks after receiving 1st booster of DPT vaccine at 16-24 months iii. To compare antibody titers against diphtheria, pertussis and tetanus in children with and without congenital heart disease 4-6 weeks after receiving 1st booster dose of the DPT vaccine at 16-24 months.

Setting: Department of Pediatrics & Microbiology, University College of Medical Sciences & GTB Hospital, Delhi Study Period: April 2024-August 2025 Ethics: Ethical clearance will be obtained from the Institutional Ethics Committee for Human Research, UCMS Consent: Informed written consent will be taken from parents or guardians of all participants Participants

All consecutive children visiting the pediatric outpatient department and admitted patients from the Pediatrics ward will be assessed for eligibility criteria.

i. Cases: Children (16-24 months) with echocardiographic confirmed congenital heart disease attending pediatric OPD or IPD and previously received 3 primary doses and at least 1 booster dose of DPT-containing vaccine.

ii. Comparison group: Healthy Children (16-24 months) without congenital heart disease attending pediatric OPD or IPD and previously received 3 primary doses and at least 1 booster dose of DPT-containing vaccine.

Exclusion criteria (both for cases and controls) i. Children receiving prolonged steroid therapy (>4 weeks) in the past 3 months ii. History of administration of blood or immunoglobulin in the last 3 months iii. Known case of malignancy or primary immunodeficiency or infant of HIV-positive Mother iv. Children suffering from other chronic diseases (e.g. chronic liver disease, chronic renal disease, thalassemia) Sample Size: 35 children (16-24 months) with echocardiographic confirmed congenital heart disease and 35 healthy children (16-24 months) who have received three primary doses and at least one booster dose of DPT-containing vaccine.

Outcome Measure: Primary: To compare the proportion of children having seroprotective antibody titers against diphtheria between cases and comparison group.

Secondary: (i) To compare the proportion of children having seroprotective antibody titers against pertussis between cases and comparison group. (ii) To compare the proportion of children having seroprotective antibody titers against tetanus between cases and comparison group (iii) To compare antibody titers against Diphtheria, Pertussis and Tetanus between cases and comparison group.