Aiello 2010a.

Methods	Cluster‐randomised trial assessing the effects of hand sanitiser and masks with masks or no intervention on ILI symptoms. The trial was conducted in University halls of residence with more than 100 student residents in a US university during the 2006 to 2007 influenza “season”. It lasted 6 weeks The units of randomisation were 7 of the 15 halls. One hall was very large (1240 residents) and the 6 remaining ones which had between 110 and 830 residents were combined into 2 clusters roughly equivalent in size. The 3 clusters were then randomised by random extraction of the clustered halls’ names out of a container. The largest hall (single‐cluster) was randomised to the mask and hand sanitiser arm, the 4 halls cluster received masks and the remaining 2 halls were assigned as controls
Participants	Willing, consenting residents aged 18 or more. Recruitment of students began in November 26 but the trial did not go “live” with distribution of intervention materials until 22 January 2007 when the first case of influenza was confirmed on campus by laboratory tests. Enrolment continued until 16 February 2007 and the study was completed on 16 March 2007. During the study period there was a 1‐week break when the majority of residents left campus. There were 1327 eligible participants, of which 1297 had a complete baseline survey and at least 1 weekly survey result (367, 378 and 552 in the mask and hand sanitiser, mask only and control groups respectively, giving a total of 1297). It is unclear what the ineligibility criteria were for the 30 missing (1327 minus 1297) but the explanation may be in the appendix.
Interventions	Alcohol‐based hand sanitiser (62% ethyl alcohol in a gel base) in a squeeze bottle and TECNOL procedure masks with ear loops (KC Ltd) and educational material or masks and educational material or no intervention. Compliance was encouraged within halls and outside. Sleep wearing was optional All participants received basic video‐linked instruction on cough etiquette and hand sanitation. At baseline and weekly during the study participants were asked to fill in a web‐based survey collecting demographic and ILI symptom data. This was supplemented by direct observation of compliance by staff Compliance with “optimal handwashing” (at least 20 seconds 5 or more times a day) was significantly higher in the sanitiser and mask arm
Outcomes	Laboratory details are described in appendix  Effectiveness: ILI, defined as cough and at least 1 constitutional symptom (fever/feverishness, chills, headache, myalgia). ILI cases were given contact nurses phone numbers to record the illness and paid USD 25 to provide a throat swab. 368 participants had ILI and 94 of these had a throat swab analysed by PCR. 10 of these were positive for influenza (7 for A and 3 for B), respectively by arm 2, 5 and 3 using PCR, 7 using cell culture  Safety: n/a
Notes	The authors conclude that “These findings suggest that face masks and hand hygiene may reduce respiratory illnesses in shared living settings and mitigate the impact of the influenza A (H1N1) pandemic”. This conclusion is based on a significantly lower level of ILI incidence in the mask and hand sanitiser arm compared to the other 2 arms after adjustment for covariates (30% to 50% less in arm 1 compared to controls in the last 2 weeks of the study)  Comparison with the ILI rate of the control arm may not be a reflection of the underlying rate of ILI because the intervention arm received instruction on hand sanitation and hand etiquette  The play of adjustments is unclear. The intra cluster correlation coefficient is reported in the footer of Table 4. Its very small size suggests lack of clustering within halls The role of the spring break is mentioned in the Discussion as are the results of this study compared to other studies included in our review (Cowling 2008 and MacIntyre 2009) The authors report that 147 of 1297 participants (11.3%) “at baseline” had ILI symptoms and were excluded from analysis. During the 6 weeks of the study 368 of 1150 participants (32%) had ILI. This averages out at about 5% per week. It is unclear what the term “at baseline” means. Presumably this means during the 2 to 3 weeks of participant enrolment. If this is so, the reason for the triggering of the interventions (tied to influenza isolation) are obscure as the trial is supposedly about ILI and an ILI outbreak was already underway “at baseline”
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised but sequence generation not reported
Allocation concealment (selection bias)	Low risk	The residence hall units were randomised by blindly selecting a uniform ticket with the name of each hall out of a container (A.S.M. and A.A.) for randomisation assignment to each study arm
Blinding (performance bias and detection bias) All outcomes	High risk	Blinding not possible
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition is reported as follows: 9, 11 and 19 ineligible and 26, 52 and 21 lost to follow up (respectively by arm). This makes a total of 39 and 99 for each cause of attrition. In total, 1297 (97%) of 1331 participants completed a baseline and at least 1 weekly survey The text reports an ITT analysis with only one ILI episode included by participant No reasons for the attrition of participants and swab volunteers are reported (were the swabs taken from a random sample or not?)
Selective reporting (reporting bias)	High risk	There is no information on the causes of ILI other than the reporting on the 10 influenza PCR‐positive swabs of 94 out of 368 students with ILI. This is a very low rate (and the Discussion confirms that the influenza season was mild) but investigation of the other known causes of ILI is not even mentioned in the text. This is especially important because stress, alcohol intake levels and influenza vaccination were a significant predictor of ILI symptoms (Table 1). The reason for selective testing and/or reporting of influenza viruses tests over the other causes of ILI are unclear especially as the study objective was focused on ILI. The text also is difficult to follow, weaving the reporting of ILI and influenza without a clear rationale