Personal protective interventions such as face masks, hand hygiene, and early isolation may have been beneficial in reducing transmission at the individual level in the home [27, 28] , although household secondary attack rates during the pandemic were similar to those with seasonal influenza [13, 29] . Their population level impact remains to be assessed. There was much debate over whether to use conventional masks or respirators in health care settings. One well-conducted Canadian trial on seasonal influenza virus transmission published during the pandemic suggested no additional advantage from N95 respirators [30] .