Mass psychogenic illness in nationwide in-school vaccination for pandemic influenza A(H1N1) 2009, Taiwan, November 2009-January 2010.

From 16 November 2009 to 22 January 2010, Taiwan investigated 23 clusters of mass psychogenic illness after vaccination (MPIV) in the nationwide in-school vaccination programme against the 2009 pandemic influenza A(H1N1). The median age of the 350 ill students (68% female) was 13 years. Intense media coverage of these events has driven public concerns about the safety of the pandemic influenza vaccine. In the future, countries should incorporate surveillance and communication strategies for MPIV in their pandemic preparedness plans.