Date	Event	Description
3 September 2014	Amended	We amended the final sentence in paragraph three under 'Effects of interventions > Comparisons showing vaccine efficacy'. The value of number needed to vaccinate (NNV) reported in the text (NNV = 28) was incorrect; we have changed it to NNV = 2.8.
9 July 2012	Feedback has been incorporated	Feedback comment and reply added to the review.
9 July 2012	New citation required but conclusions have not changed	A new author joined the team to update this review.
16 November 2011	New search has been performed	For this 2011 update we included the following 15 new trials and data sets: (aa Bracco Neto 2009a; aa Bracco Neto 2009b); (ba Cochran 2010a; ba Cochran 2010b; ba Cochran 2010c); (ba Eisenberg 2008a; ba Eisenberg 2008b); ba Gilca 2011; ba Kelly 2011; ba Kissling 2011; ba Mahmud 2011; ab Mallory 2010; ca Ortqvist 2011; ab Plennevaux 2011; (ba Staat 2011a; ba Staat 2011b); ba Valenciano 2011; ba Van Buynder 2010; ca Yin 2011; cb MPA 2011. Readers are reminded that one study may provide multiple data sets (e.g. Bracco Neto 2009 a and b). We excluded 10 trials (Ambrose 2011; Belshe 2008; Fujieda 2008; Haba‐Rubio 2011; Jansen 2008; Kissling 2011a; McMahon 2008; Muhammad 2011; Stowe 2011; Wu 2010).
20 February 2008	New citation required and conclusions have changed	Substantive amendment
20 February 2008	New search has been performed	For the 2007 update, we re‐ran the searches and identified 1090 possible titles of interest. We retrieved 15 and excluded 5: Neuzil 2006, Hambidge 2006, and France 2004 because they were non‐comparative; Daubeney 1997 because it was not carried out in healthy children; and Gendon 2004 because it assessed the impact of vaccinating children to prevent influenza in the elderly. We included 10 studies. Two were placebo‐controlled trials of cold‐adapted live attenuated influenza vaccine (CAIV) (Tam 2007; Vesikari 2006); two were case‐control studies assessing respectively the efficacy and safety of trivalent influenza vaccine (TIV) (Anonymous 2005; Goodman 2006); three were prospective cohort studies assessing the effectiveness of respectively CAIV (Wiggs‐Stayner 2006), virosomal vaccine (Salleras 2006), and TIV vaccines (Fujieda 2006); and one was a retrospective cohort study assessing the effectiveness of an undescribed vaccine (Allison 2006). The remaining included studies were a prospective cohort study reporting effectiveness and safety of CAIV in school‐aged children (King 2006), and a prospective single‐blind cohort study assessing the effectiveness of TIV against otitis media (Ozgur 2006). Our conclusions remain unchanged.
15 January 2008	Amended	Converted to new review format