Comparative safety evaluation of 7-valent and 13-valent pneumococcal vaccines in routine paediatric vaccinations in four Italian regions, 2009 to 2011

This study was aimed at estimating the risk of all types of adverse events following immunisation (AEFI), neurological events and convulsions following the co-administration of 13-valent pneumococcal polysaccharide conjugate vaccine (PCV13) with hexavalent vaccine. Paediatric spontaneous reports and exposure to vaccinations in four Italian regions were available. The estimated incidence rate ratio (IRR) for AEFI following co-administration of hexavalent vaccine with either PCV13 or PCV7 was 1.08 (95% confidence interval (CI): 0.91-1.28); the IRR for, respectively, neurological events and convulsion following co-administration of PCV13 with hexavalent vaccine were 1.27 (95% CI: 0.85-1.89) and 1.43 (95% CI: 0.70-2.91). Co-administration of PCV13 with hexavalent vaccine had a protective effect against AEFI (IRR?=?0.59; 95% CI: 0.49-0.72). This protective effect was not observed for neurological events or convulsions following co-administration of PCV13 with hexavalent vaccine compared with single administration (IRR?=?1.44; 95% CI: 0.77-2.67 and IRR?=?1.46; 95% CI: 0.50-4.25, respectively). We observed a trend of increased risk of neurological events or convulsions following PCV13 used in routine practice. Analysis of spontaneously reported data is a quick method to estimate associations between vaccines and less common adverse events. Given methodological limitations these findings cannot be conclusive and require further investigations. .