Italian post-marketing surveillance for adverse event reports after MF59-adjuvanted H1N1v vaccination

Abstract

According to European recommendations, the Italian Medicines Agency (AIFA) required close monitoring of the safety of the MF59-adjuvanted H1N1v vaccine, which was the only vaccine available in Italy for prophylaxis of the A/H1N1 (2009) pandemic influenza. From October 2009 to June 2010, the Italian Pharmacovigilance Adverse Event (AE) Spontaneous Reporting System [Rete Nazionale Farmacovigilanza] (RNF) received 1330 reports of AEs temporally related with the pandemic influenza vaccination out of a total of 924,057 doses administered. Among these, 1,162 (87.37%) AE reports were classified 'non serious', 91 (6.84%) 'serious', 3 (0.23%) had a fatal outcome and 74 (5.56%) did not include the degree of seriousness. Among the serious AE reports, some unexpected AEs emerged. Even though some typical vaccine safety issues which emerged should be further explored, such as vaccination in pregnancy, the analysis of all AE reports sent to RNF shows that the vaccine has a well-tolerated safety profile which resembles that of the already available seasonal influenza vaccines. This contrasts with the widespread public concern about its safety, which has been one of the major causes of the low vaccination rate observed in Italy, as well as in other countries.