Bordetella Pertussis (bp): Impact of Tdap Maternal Immunization Strategy in a Pediatric Hospital in Argentina. 2003-2016

Background: Whooping cough continues being a major cause of morbidity and mortality in infants younger than 1 year old. In 2012 Argentina introduced Tdap in pregnancy to prevent infant mortality. The aim was to describe the clinical and epidemiological profile of Bordetella pertussis comparing pre and post Tdap vaccine periods. Methods & Materials: All laboratory PCR confirmed Bp cases between December 2003 and December 2016 were included in “R. Gutierrez” Children's Hospital. Analysis was performed comparing Bp hospitalization rates (per 10,000 discharges) between pre-vaccination (PreV) 2003-2011 and post-vaccination maternal immunization strategy (PostV) 2013-2016 periods excluding intervention year (2012). Results: From 1046 suspected cases, 337 (32.2%) were Bp confirmed cases: median age 3 months (IQ = 2-7months), 39% < 3 months, 69% < 6 months, 84% < 12 months; 55% females; 18% had underlying conditions, the most frequent recurrent respiratory disease 73%; 1% were malnourished, 10% born preterm and 1% immunosuppressed; 82% required hospitalization, median length of stay was 6 days (IQ = 4-10 days), 17% in UCI. Confirmed cases showed a seasonal pattern predominantly from September through February (spring-summer). Bp hospitalization rate (HR) and lethality rate is shown in Figure 1. In comparison with PreV, PostV cases were older (3 vs 9 months;p < 0.001), required less hospitalization (86.9% vs 67.6%;p < 0.001) and Bp HR decreased (22.3 vs 11.6;p < 0.001). No difference found in gender, length of stay days or intensive care requirement. Lethality rate 5%(14/277), all fatal cases in PreV period. Conclusion: Confirmed cases were mostly healthy infants younger than 1 year old who had not completed their primary immunization schedule. In PostV Bp cases were older and there was a significant decrease in the hospitalization rate. There were no fatal cases in our centre after this intervention.