What is the evidence that COVID-19 personal protective equipment should include shoe covers?
April 7, 2020
Lead author:
Kamlesh Khunti, University of Leicester
Series editor:
Trish Greenhalgh
Contributing authors:
Trish Greenhalgh and Xin Hui Chan, University of Oxford
Quentin Durand-Moreau and Sebastian Straube, University of Alberta, Canada
Declan Devane and Elaine Toomey, Evidence Synthesis Ireland and Cochrane Ireland
Anil Adisesh, University of Toronto, and St. Michael’s Hospital, Toronto, Canada
Lawrence Ross, Children’s Hospital Los Angeles, and Keck School of Medicine, USA
On behalf of the Oxford COVID-19 Evidence Service Team
Centre for Evidence-Based Medicine
Nuffield Department of Primary Care Health Sciences
University of Oxford
Correspondence to kk22@leicester.ac.uk
VERDICT
Current guidance on personal protective equipment (PPE) in the context of COVID-19 does not specifically mention shoe covers. This review found no relevant trials. In a single observational study, a single positive swab for SARS-CoV-2 was obtained from the shoe of a healthcare worker. General occupational health guidance recommends shoe covers when there is a risk of splashing from infected body fluids.Further research is needed on whether shoe covers should be added to PPE.
We found no systematic reviews or randomised trials that looked at effectiveness of shoe covers as part of personal protective equipment (PPE), either in the context of COVID-19 or in other outbreaks. A single observational study of three healthcare staff in a COVID-19 centre in Singapore identified a single positive swab from a shoe front.
It is important to assess contagion risk of every encounter and take appropriate precautions. Where close contact is required, guidance for full personal protective equipment should be followed but this does not currently specify shoe protection.
DETAIL
Context
We were asked to find out whether and in what circumstances shoe protective equipment (e.g. covers) should be worn by healthcare staff as part of PPE when seeing patients with COVID-19.
Background
The inclusion of protective shoe covers or footwear as a component of PPE for prevention of acquisition and dissemination of pathogenic microbial agents by healthcare staff derives from documentation of extensive floor contamination with bacterial pathogens. The effectiveness of shoe coverings in diminishing bacterial pathogen acquisition in ICUs has not been clearly demonstrated.[1-3].
To further assess the role of healthcare facility surfaces (including floors) to serve as reservoirs for pathogen dissemination, non-pathogenic viruses have been introduced as surrogate markers. Inoculation of such viruses on high touch surfaces has allowed detection of these agents on hands as well as environmental surfaces.[4] A study using a non-pathogenic bacteriophage, MS2, identified rapid dissemination to footwear and hands of patients and high touch surfaces. Further, contamination in adjacent rooms suggested that healthcare staff may contribute to such spread.[5]
COVID-19 is spread by four means: contact (direct or via a fomite); droplet infection (droplets from the respiratory tract of an infected individual during coughing or sneezing are transmitted onto a mucosal surface or conjunctiva of a susceptible individual or environmental surfaces); via aerosols (particularly during procedures such as intubation); and faeco-oral [6]. In one recent laboratory study, SARS-CoV-2 survived longer than other respiratory viruses when artificially aerosolised.[7]
There is little real-world research comparing shoe protective equipment in the context of influenza or other relatively benign respiratory conditions. There are no published head-to-head trials of these interventions related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, the virus that causes COVID-19) or trials in any setting.
One recent observational study in a dedicated COVID-19 outbreak center in Singapore collected PPE swabs from study physicians on their exiting airborne isolation rooms of COVID-19 patients. Out of the 3 staff members assessed, one PPE swab, from the surface of a shoe front, was positive [6], and concomitant widespread environmental high touch surface contamination was confirmed.[6] Further study at this healthcare facility was expanded to 30 healthcare staff caring for infected patients and PPE contamination was not identified.[8] However, none of the infected patients was receiving ventilatory support and aerosol generating procedures (AGPs) were not carried out during sampling. In addition, patients were all in airborne infection isolation rooms undergoing a minimum of 12 air exchanges/hour and the median time healthcare staff spent in these rooms was 6 minutes.[8] Widespread environmental contamination from SARS-CoV-2 was demonstrated in a study from the University of Nebraska (awaiting publication) although shoe covers were not specifically evaluated.[9]
It is probably self-evident that shoe protective equipment should not be considered as an isolated intervention. Other protection includes hand hygiene, eye protection, surgical or respirator masks, aprons or gowns, and gloves [10]. The World Health Organization (WHO) has produced technical specifications for these items, based on simulation exercises using data from past SARS and MERS outbreaks. This guidance does not mention shoe protection.[10]
CURRENT GUIDANCE
Official UK guidance updated in April 2020 does not make any recommendations for use of shoe protective equipment.[11]
Policy guidance from various bodies (e.g. Public Health England, WHO) emphasizes the need to assess the contagion risk of an encounter and use the recommended combination of equipment for that situation. In particular, suitable PPE including respirators, goggles or visor, long-sleeved gown, waterproof aprons are needed to protect against small airborne particles in AGPs such as intubation. Surprisingly, the WHO technical specifications on PPE does not include any comment on shoe covers.[10, 11]
The WHO has stated that human-to-human transmission has been documented, including in healthcare workers, and AGP may play a role in the spread of the disease [8].
The WHO distinguishes different levels of risk – for example: [12]
- Standard precautions e.g. for staff conducting triage: hand hygiene + require any patient with suspected COVID-19 to wear a facemask;
- ‘Contact and droplet precautions’ for suspected or confirmed case of COVID-19 not involving AGPs: requires hand hygiene, surgical mask, gown, goggles, gloves;
- ‘Airborne precautions’ for suspected or confirmed case of COVID-19 requiring healthcare facility admission and AGP: requires hand hygiene, respirator mask, gown, goggles, gloves;
- Collection of specimens for laboratory diagnosis: if undertaken via an AGP, requires hand hygiene, respirator mask, gown, goggles, gloves plus additional precautions
However, WHO guidance also does not make any recommendations on use of shoe protective equipment. Interim infection control recommendations from the CDC pertaining to SARS-CoV-2 also do not include use of shoe covers for PPE of patients with SARS-CoV-2. Published guidelines from the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the CDC do not include recommendations for shoe cover use in patients placed in airborne, droplet and contact precautions,[13] Moreover, with regard to environmental service personnel the CDC’s online guidance specifically states: “Shoe covers are not recommended at this time for personnel caring for patients with COVID-19” in their Healthcare Infection Prevention and Control FAQs.[14]
The US Occupational Safety and Health Administration guidelines do recommend shoe covers where there is a risk of splashing from potentially infected body fluids.[15]
SEARCH STRATEGY
We conducted an initial search with a brief database search of Medline and Cochrane databases without date restrictions. We also conducted searches of Google Scholar. We used the following key words “Shoes”[Mesh] OR shoes*[tw] OR “shoe”[tw] OR “overshoe”[tw] OR “rubber boots”[tw] OR “rubber boot”[tw] combined with influenza [tw[ OR exp Influenza [Mesh] OR Coronavirus Infections [Mesh] OR Coronavirus [Mesh] OR coronavirus [tw] OR [COVID] OR SARS Virus [MESH] sars [TW] OR Severe Acute Respiratory Syndrome [MESH] OR mers [tw] OR Middle East Respiratory Syndrome Coronavirus [Mesh] OR respiratory infection [tw] OR Respiratory Tract Infections [Mesh] combined with “respiratory tract infections”, “randomized controlled trial” and “systematic review”.
We identified 114 randomised controlled trials and 25 systematic reviews on Medline. These were screened by title and abstract to confirm that no relevant trials were in the literature. We identified one relevant systematic review. [16]
Critical appraisal of systematic reviews
Verbeek et al. 2019 [16]
We identified one Cochrane systematic review that included 17 studies with 1950 participants evaluating 21 interventions of which 10 were Randomised Controlled Trials. There were no separate studies evaluating shoe protective equipement.
Evaluation against the AMSTAR II checklist, we judged the review to be of good quality. We are currently await the update of this systematic review (expected date April 2020).
Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited should be checked. The views expressed in this commentary represent the views of the authors and not necessarily those of the host institution, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.
AMSTAR II checklist – Verbeek et al. 2019:
1. Did the research questions and inclusion criteria for the review include the components of PICO? Yes
2. Did the report of the review contain an explicit statement that the review methods were established prior to conduct of the review and did the report justify any significant deviations from the protocol? Yes
3. Did the review authors explain their selection of the study designs for inclusion in the review? Yes
4. Did the authors use a comprehensive literature search strategy? Yes
5. Did the authors perform study selection in duplicate? Yes
6. Did the authors perform data extraction in duplicate? Yes
7. Did the review authors provide a list of excluded studies and justify the exclusions? Yes
8. Did the authors describe the included studies in adequate detail? Yes
9. Did the review authors use a satisfactory technique for assessing the risk of bias (RoB) in individual studies that were included in the review? Yes
10. Did the review authors report on the sources of funding for the studies included in the review? Yes
11. If meta-analysis was justified did the review authors use appropriate methods for statistical combination of results? Yes
12. If meta-analysis was performed did the review authors assess the potential impact of RoB in individual studies on the results of the meta-analysis or other evidence synthesis? Yes
13. Did the review authors account for RoB in individual studies when interpreting/ discussing the results of the review? Yes
14. Did the review authors provide a satisfactory explanation for, and discussion of, any heterogeneity observed in the results of the review? Yes
15. If they performed quantitative synthesis did the review authors carry out an adequate investigation of publication bias (small study bias) and discuss its likely impact on the results of the review? No – publication bias not discussed
16. Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review? Yes
REFERENCES
1. Gupta, A., et al., A Study of bacteriological profile in an ICU set up and effect of barrier nursing on the existing profile. Indian Journal of Anaesthesia, 2005. 49(1): p. 31-6.
2. Hambraeus, A., Importance of floor contamination as a source of airborne bacteria. Journal of Hygiene (London), 1998. 80: p. 169-170.
3. Gupta, A., et al., Impact of Protective Footwear on Floor and Air Contamination of Intensive care Units. Medical Journal Armed Forces India, 2007. 63(4): p. 334-336.
4. Oelberg, D.G., et al., Detection of pathogen transmission in neonatal nurseries using DNA markers as surrogate indicators. Pediatrics, 2000. 105(2): p. 311-315.
5. Koganti, S., et al., Evaluation of hospital floors as a potential source of pathogen dissemination using a nonpathogenic virus as a surrogate marker. infection control & hospital epidemiology, 2016. 37(11): p. 1374-1377.
6. Official Guidance, COVID-19: Guidance for infection prevention and control in healthcare settings. Version 1.0. 2020. Accessed 21.3.20 at: Department of Health and Social Care (DHSC), Public Health Wales (PHW), Public Health Agency (PHA) Northern Ireland, Health Protection Scotland (HPS) and Public Health England
7. Ong, S.W.X., et al., Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient. Jama, 2020.
8. van Doremalen, N., et al., Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine, 2020.
9. Ong, S. and et al, Absence of contamination of PPE by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-2). Infection Control and Hospital Epidemiology, 2020. in prss (accepted manuscript).
10. Santarpia, J.L., et al., Transmission Potential of SARS-CoV-2 in Viral Shedding Observed at the University of Nebraska Medical Center. medRxiv, 2020.
11. World Health Organisation, Requirements and technical specifications of personal protective equipment (PPE) for the novel coronavirus (2019-ncov) in healthcare settings. 2020. Accessed 21.3.20 at
https://www.google.com/urlsa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=2ahUKEwjS2di4q3oAhVXh1wKHWeGDvEQFjACegQIARAB&url=https%3A%2F%2Fwww.paho.org%2Fen%2Ffile%2F59297%2Fdownload%3Ftoken%3Dbr2NtqhR&usg=AOvVaw1Sicp3C6m3fjFmMfIeox7R
Geneva.
12. Public Health England, When to use a face mask or FF£ respirator. 2020. Accessed 21.3.20 at https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/874310/PHE_11606_When_to_use_face_mask_or_FFP3_02.pdf
London.
13. Public Health England, COVID-19: Infection prevention and control. . 2nd April 2020. Acccessed 3.4.20 at London: Gov.uk.
14. World Health Organisation, Infection prevention and control during health care when COVID-19 is suspected: Interim guidance. 19th March 2020. Accessed 6th April 2020 at https://www.who.int/publications-detail/infection-prevention-and-control-during-health-care-when-novel-coronavirus-(ncov)-infection-is-suspected-20200125
Geneva: WHO.
15. Centers for Disease Control and Prevention (US), Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in Healthcare Settings. March 2020. Accessed 7th April 2020 at https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html Atlanta: CDC.
16. Occupational Safety and Health Administration (US), Worker protections against occupational exposure to infectious diseases. March 2020. Accessed 7th April 2020 at: Washington: OHSA.
17. Verbeek, J., et al., Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff. Cochrane Database Syst Rev., 2019.
