Figure 5 is a line graph showing the national proportion of participants with ILI (defined as fever and cough) each week (ending Sunday) from 2009 to 2014, stratified by vaccination status (vaccinated versus unvaccinated with the seasonal influenza vaccine). For the majority of survey weeks there is a higher proportion of unvaccinated participants with ILI, as compared to vaccinated participants. Peak ILI activity for 2013 was during the week ending 25 August (4.3% in the unvaccinated group). This is also when divergence between the vaccinated and unvaccinated participants’ ILI prevalence was highest. Peak ILI activity for 2014 was during the week ending 24 August (5.0% in the unvaccinated group). However, divergence between the vaccinated and unvaccinated participants’ ILI prevalence was highest during the week ending 29 June.