Unusually high impact of influenza B during the early 2012-2013 influenza season in Wales - epidemiology and clinical analysis of the first 100 cases

Abstract

Influenza B is often regarded as the milder form of the disease. The early 2012-2013 season in Wales saw the highest rate of influenza B-associated primary care consultations since 1994-1995 and considerable hospitalisations. This report summarises features of the first 100 confirmed cases during 2012-2013 in Wales. Case information was sourced from routine laboratory testing and virological surveillance. Influenza B (Yamagata lineage) viruses dominated, mainly affecting younger adults, admission to critical care was unexpectedly common. Low vaccine uptake amongst at-risk patients may have contributed to the burden of influenza in secondary care in Wales.