This initiative was taken following the indication of a potential association between the 2009 pandemic influenza A(H1N1) monvalent vaccine and the occurrence of narcolepsy following reports, especially in children from Finland and Sweden.
This retrospective cohort study, carried out in two hospitals in Toronto , Canada, looked for thrombotic events in all hospitalised patients with confirmed pandemic A(H1N1)2009 influenza. It then went on to describe the nature of these vascular events and the associated factors. The publication has single illustrative a case report and a case series with a retrospective cohort study.
This review published by the WHO aims at answering important questions among the Known Unknowns areas which were unclear at the beginning of the 2009 pandemic