2281. Impact of the Introduction of the Haemophilus influenzae Type B Conjugate Vaccine in Southern India

BACKGROUND: Haemophilus influenzae type b was the leading cause of bacterial meningitis in infants and children below the age of 2 years prior to the introduction of H. influenzae type b conjugate vaccines. In December 2011, the Indian government introduced H. influenzae b vaccine in the state of Tamil Nadu. Prospective surveillance for bacterial meningitis was established at the Institute of Child Health in Chennai to evaluate the etiology of meningitis and the impact of the vaccine. METHODS: Infants aged 1 to 23 months who were admitted to the hospital with symptoms of suspected bacterial meningitis were enrolled and lumbar puncture was performed. Cerebrospinal fluid samples were analyzed for white blood cells, protein, and glucose. Bacterial culture and a latex agglutination test for common bacterial pathogens were performed. RESULTS: Between January 2009 and March 2014, 4,770 children with suspected bacterial meningitis were enrolled. Prior to the introduction of the vaccine, an average of 11.7 cases of H. influenzae b meningitis and 31.1 cases of probable meningitis with no etiology were identified each year. After introduction, the number of cases was reduced by 79% and 44% respectively. The average H. influenzae b vaccine coverage after introduction was 69% among all children with clinically suspected meningitis. In contrast, the mean number of aseptic meningitis and pneumococcal meningitis cases remained stable throughout the pre and post vaccination period; 28.2 and 4.8 per year, respectively. CONCLUSION: H. influenzae b conjugate vaccine reduced the number of cases of H. influenzae b meningitis and probable meningitis within the first two years of its introduction. The impact against meningitis was higher than the vaccination rate, indicating indirect effects of the vaccine. India has recently scaled up the use of H. influenzae b conjugate vaccine throughout the country which should substantially reduce childhood meningitis rates further in the country. DISCLOSURES: M. Santosham, Merck: Investigator, Research support. GlaxoSmithKline: Investigator, Research support. Pfizer: Investigator, Research support. Merck: Scientific Advisor, Speaker honorarium. GlaxoSmithKline: Scientific Advisor, Speaker honorarium. Pfizer: Scientific Advisor, Speaker honorarium.