Nishiura 2005.

Methods	Case‐control study carried out during the SARS outbreak (26 February 2003 to 28 April 2003) in Hanoi, Vietnam. The study aimed at assessing the relationship between SARS infection and behaviour. The study population was based at the Hanoi French Hospital (HFH) and followed the outbreak during 3 phases. The first phase (26 February to 4 March 2006) in which an index case and 9 suspected secondary cases were admitted/cared for. The second phase (8 March to 11 March 2003) in which outpatients were closed and staff no longer returned home as the outbreak spread and the third phase (11 March 2003 to 28 April 2003) in which the HFH was closed to all other then SARS cases who were isolated
Participants	Description of cases: 29 surviving people with laboratory confirmed SARS cases either admitted and retained or transferred to other hospitals. Nine cases did not take part (5 died, 1 refused and 3 had relocated). Twenty‐eight were HCWs employees of the HFH and 1 a relative of a patient. Substantial exposure and behaviour were documented through observation and questionnaires Description of controls: 90 people aged > 20 who provided written consent with substantial SARS exposure, 57 of whom were HFH employees
Interventions	Handwashing before contact with SARS patient Handwashing after contact with SARS patient Masks Gloves Gowns All measures combined Analysis by epidemic stage is reported
Outcomes	SARS infection
Notes	Risk of bias: low Notes: the authors conclude that masks (OR 0.3, 95% CI 0.1 to 0.7) and gowns (OR 0.2, 95% CI 0.0 to 0.8) were significantly associated with protection during phase 1 but in Phase 2 masks (OR 0.1, 95% CI 0.0 to 0.3) and all measures (OR 0.1, 95% CI 0.0 to 0.3) were associated with protection probably because of the increased awareness of the danger of the outbreak and increase us of measures ‐ this is confirmed by the results of the mathematical model in the second part of the study. A well‐written and reported study
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	N/A
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding (performance bias and detection bias) All outcomes	Unclear risk	N/A
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	N/A
Selective reporting (reporting bias)	Unclear risk	N/A