Adverse events associated with 2010 CSL and other inactivated influenza vaccines.

The 2010 trivalent influenza vaccine (TIV) manufactured by CSL Biotherapies (CSL) was associated with increased febrile reactions, including febrile convulsions, among Australian children. CSL is one of the few manufacturers that use deoxycholate as the virus-splitting agent in the manufacture of TIV. Clusters of adverse events following immunisation (AEFI) have been previously linked to other deoxycholate-split TIV formulations in Europe and Canada. We hypothesise that suboptimal virus splitting or other mechanisms related to the use of deoxycholate may have played a role in adverse events linked to the 2010 CSL TIV. This hypothesis garners support from a recent United States Food and Drug Administration warning letter indicating that CSL failed to determine optimal splitting conditions for new virus strains and that assays to assess virus splitting had not been validated. While there may be other causes, the use of deoxycholate should be further explored. Comprehensive and timely investigations of AEFI, especially those involving children, are necessary to prevent their recurrence and to maintain public confidence in vaccination programs.