Elevated Glycated Hemoglobin Is Associated with Reduced Antibody Responses to Vaccinations in Children

Childhood obesity is a major health concern, and it is associated with an increased risk of infectious morbidity. Previous studies found a decrease in protective antibody titers in obese adults after hepatitis B, influenza, and tetanus vaccination. We aimed at determining whether obesity or abnormal hemoglobin A1C (HBA1C) levels are associated with altered antibody responses in children. Children (8-18 years) who have completed routine childhood immunization were recruited. Serum samples were tested by the enzyme-linked immunosorbent assay method for antibody levels to Diphtheria, Tetanus, Haemophilus influenzae type B (HIB), and Streptococcus pneumoniae, along with serum HBA1C levels. An electronic medical record review on the frequency of emergency visits for infection was conducted. Spearman rank correlation, Fisher-exact, and Pearson's Chi-squared tests were used for statistical analysis. There was an overall negative correlation between body mass index (BMI) percentile and the majority of pneumococcal subtypes, Diphtheria and Tetanus titers, although not statistically significant. There was a statistically significant negative correlation between HBA1C level and the S. pneumoniae serotype P9N (P = 0.037), P4 (P = 0.017), P12 (P = 0.023), P19F (P = 0.050), and HIB (P = 0.001). On average, individuals with elevated HBA1C levels had more frequent emergency room visits for infection (P = 0.029) and more viral infections (P = 0.023) as compared with children with normal HBA1C. Children with higher HBA1C levels were more likely to have lower pneumococcal and HIB titers and increased rates of emergency room visits for infection in a prospective, population-based cohort study. Although not statistically significant, there was an overall negative correlation between BMI percentile and titers for routine childhood vaccines.