Houlihan 2017.

Methods	Retrospective cohort study Invitations to participate were sent to individuals known to the authors, and through organisations supporting EMT deployment involving UK‐based staff, including non‐governmental organisations (NGOs), UK government‐affiliated institutions, and the London School of Hygiene & Tropical Medicine (LSHTM). The participants filled in a questionnaire with information about PPE use. They then underwent a blood test to assess their antibody status. The researchers assessed the participants' risk of being exposed to EVD based on an independent algorithm.
Participants	N = 300 Individuals who returned to the UK or Ireland after responding to the West African EVD epidemic completed the survey. Of these N = 268 returned material for IgG assessment (median age 36 y range 30‐45 y;57% female; 35% lab staff, 26% physicians, 20% nurses, 19% other) In addition, there were N = 53 non‐exposed control participants included who had not left the UK (median age 35 y range 31‐40 y; 66% female)
Interventions	There were 2 interventions that were of interest. (1) PPE removal with or without chlorine spray, (2) PPE removal with and without assistance. However, almost all clinical staff had used both interventions as compared to laboratory staff which had not used them. Because there was also a big difference in the likelihood of exposure between these two occupational groups, the effect of protection of these measures could therefore not be analysed.
Outcomes	Level of IgG antibody against Ebola Virus as an indicator of infection .
Notes	Country: UK; Funding by Wellcome Trust: Enhancing Research Activity in Epidemic Situations. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript; one author has received funding from the Wellcome Trust via the University of Liverpool and also received non‐financial support from NHSBT, as part of the Convalescent Plasma Study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Confounding NRS	Low risk	Differences related to: 1. prior experience with PPE‐ No 2. healthcare qualification or education of HCW‐No (clinical, lab or other role) 3. age‐No 4. sex‐ No 5. ambient temperatures‐ No (all restricted to Africa) 6. stressful activities‐ Yes (work roles varied depending on qualifications)
Selection Bias NRS	High risk	Sample based on snowball sampling
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants were not aware of exposure status when they reported their exposures.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Researchers knew who was rated as 'high risk' but objective outcome measure. Therefore unlikely that it has been influenced
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Convenience sample; from sample 10.7% did not react
Selective reporting (reporting bias)	Unclear risk	No protocol provided
Other bias	Low risk	No other sources of bias detected