This a rapid response. Rapid responses are electronic letters to the editor. Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis BMJ 2013; 347 doi: http://dx.doi.org/10.1136/bmj.f5061 (Published 23 August 2013) Cite this as: BMJ 2013;347:f5061 Recent rapid responses Rapid responses are electronic letters to the editor. They enable our users to debate issues raised in articles published on bmj.com. Although a selection of rapid responses will be included as edited readers' letters in the weekly print issue of the BMJ, their first appearance online means that they are published articles. If you need the url (web address) of an individual response, perhaps for citation purposes, simply click on the response headline and copy the url from the browser window. Unfortunately, pregnancy did increase the risk of death during the 2009 pandemic 16 January 2014 A recent meta-analysis conducted by Mertz and collaborators [1] assessed the strength of evidence for factors representing a higher risk for influenza-related