Does the change in the immunization dosing schedule of 10-valent pneumococcal conjugate vaccine has any impact among children in the northwest of Sao Paulo, Brazil?

Background 10-Valent pneumococcal conjugate vaccine (PCV-10) is the immunization routine in Brazil since 2010. In 2016, the immunization schedules changed from 3+1 to 2+1 doses for children in the first year of age. The analysis of the relationship with the occurrence of invasive pneumococcal disease (IPD) in the different schedule vaccine period becomes relevant. Methods This was a retrospective cohort study evaluating the incidence, general characteristics and in-hospital clinical outcomes for invasive pneumococcal infections. We included community-associated infections by microbiological laboratory tests from 2010 to 2019. According to the immunization schedule, we divided the groups in 3+1 and 2+1. We collected clinical data from medical records. Results We identified 62 cases of pneumococcal infections (3+1=38, 2+1=24). Overall, the incidence density in the two immunization schedules remains equal. The most common serotype was 19A. The outcomes of sepsis, septic shock, chest drain open or closed, complicated pneumonia and death, did not show any difference in the two schedules. Regarding the survival curves, the only one that would apply a proportional risk model (the curves do not intersect), is related to the length of stay in the ICU. In this case, the raw hazard ratio was 2.46 95% CI (0.93; 6.48) and the adjusted was 2.52, 95% CI (0.82; 7.81). Conclusions The two immunization schedules of PVC-10 show an equal performance in our service. Our results may highlight a serotype replacement with no worse outcomes.