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\begin{document}

\title{Personal protective equipment (PPE) and infection among healthcare
workers -- what is the evidence?}



\author[1]{Zixing Tian}%
\author[2]{Mike Stedman}%
\author[3]{Martin Whyte}%
\author[4]{Simon Andersen}%
\author[5,6]{George Thomson}%
\author[7]{Adrian Heald}%
\affil[1]{The University of Manchester}%
\affil[2]{Res Consortium}%
\affil[3]{Affiliation not available}%
\affil[4]{University of West Indes}%
\affil[5]{International Journal of Clinical Practice}%
\affil[6]{Royal Cornwall Hospital}%
\affil[7]{Salford Royal Hospitals NHS Trust}%


\vspace{-1em}



  
  \date{May 19, 2024}


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\selectlanguage{english}
\begin{abstract}
The worldwide outbreak of coronavirus disease-19 (COVID-19) has already
put healthcare workers (HCWs) at a high risk of infection. The question
of how to give HCWs the best protection against infection is a priority.
Our literature review has indicated that the degree of protection
required in looking after people with COVID-19 infection, is dependent
on the particular environment to which the HCW is exposed. Covering more
of the body could provide better protection for HCWs. Of importance, it
is not just the provision of PPE but the skills in donning and doffing
of PPE that are important, this being a key time for potential
transmission of pathogen to the HCW and in due time from them to others.
In relation to face masks, the evidence indicates that a higher-level
specification of face masks (N95) seems to be essential to protect HCWs
from Coronavirus infection. Evidence specifically around PPE and
protection from the COVID-19 virus is minimal and at the level of
anecdotal reports only.%
\end{abstract}%



\sloppy


\textbf{Background}

The worldwide outbreak of coronavirus disease (COVID-19) has already put
healthcare workers (HCWs) at a high risk of
infection.\textsuperscript{1} The question of how to give HCWs the best
protection against infection is a priority. Reports of personal
protective equipment (PPE) shortages, with regional and international
differences in the approach to deployment of PPE have repeatedly made
national media headlines.\textsuperscript{2} During the past few months,
as the UK has tackled the coronavirus pandemic, HCWs including doctors
and nurses have complained of a lack of adequate PPE kit such as gowns,
masks and gloves.

Many readers of this journal have been working closely with patients
with COVID-19 in recent weeks, and so have a personal interest in
ensuring that such evidence as exists is made available and applied in
the everyday clinical setting in the UK and elsewhere.

\textbf{Types of PPE}

The `level' of PPE is matched to the clinical environment and the
procedures being undertaken. Generally the levels are categorised as
standard, or those that are designed to mitigate against contact,
droplet or airborne pathogensa and enhanced PPE (full-body) for highly
infectious or `high-consequence' pathogens. A Cochrane review evaluated
the effect of full-body PPE used by HCWs exposed to highly infectious
diseases, defined as causing such as Ebola Virus Disease, COVID-19 and
severe acute respiratory syndrome (SARS).\textsuperscript{3} The review
highlighted eight studies comparing types of whole-body PPE. Key to
efficacy was a better fitting gown around the neck, wrists and hands
(relative risk, RR 0.08, 95\% confidence interval, CI 0.01-0.55), a
better cover of the gown-wrist interface (RR 0.45, 95\% CI 0.26-0.78).
Covering more parts of the body could provide a better protection. For
example, a powered, air-purifying respirator with coverall may protect
better than an N95 mask with a gown (RR 0.27, 95\% CI 0.17- 0.43).
However, these conclusions were based on simulation studies with small
sample sizes.\textsuperscript{3}

\textbf{Removal of PPE after patient contact}

Removal of PPE is a sequenced procedure, with studies showing that there
are high rates of doffing errors even with basic PPE. Considerable
contamination can occur during PPE doffing\textsuperscript{4} but
simulation training can dramatically improve
performance\textsuperscript{5}, although the durability of performance
is uncertain. Modifications to full-body PPE could reduce contamination
when it is being removed, for instance by the provision of `grab' tabs
to facilitate doffing of masks or gloves.\textsuperscript{3}

\textbf{Evidence from SARS}

China has considerable experience in dealing with SARS and COVID-19, so
we additionally searched the Chinese Biomedicine Literature Database to
find articles published in Chinese. Three case-control studies examining
PPE and HWCs infection during the SARS outbreak 2002-2004 were found,
These included 276 infected HCWs and 2099 non-infected
HCWs.\textsuperscript{6-8} The most commonly used PPEs were masks,
followed by gloves, protective clothing, and
goggles.\textsuperscript{8}These studies had similar findings that
wearing any of: facemasks, gowns, gloves, goggles and footwear when
caring for patients with SARS was associated with a lower risk of HCWs
infection (\emph{P} \textless{}0.05). The combination of different types
of PPEs could reduce the risk of infection. In one study, 16/26 (61.5\%)
of HWP (involved in SARS patient contact) without PPE were infected,
whereas none was infected when using all types of PPEs recommended by
WHO.\textsuperscript{7 9}

FFP2 face masks are similar to N95 face masks and both meet the WHO
guidance for protection against COVID-19. FFP3 face masks, which are
similar to N99 face masks, have a better filter performance based on the
minimum filtration of 99\%. All these four types of masks can block both
liquid and solid aerosols.

N95 face masks, surgical face masks, cotton face masks and disposable
face masks were all used by HCWs during SARS outbreak. Compared with
those without facemasks, HCWs who wore more than 12-layer cotton masks
had a lower risk of infection (OR 0.78, 95\% CI
0.60-0.99).\textsuperscript{7} Two studies found that compared without
wearing any masks, wearing simple paper face masks did not have a
significantly protective effect.\textsuperscript{7 10} Ma \emph{et al}
(2004) also found that low-quality face masks (less than 12-layer cotton
masks) were associated with a higher risk of infection (OR 76.68, 95\%
CI 16.74-351.31).\textsuperscript{6} Unsurprisingly, N95 facemasks, were
the most efficacious in reducing HCW infection.\textsuperscript{11}

Tight-fitting respirators (such as disposable FFP2 masks and reusable
half masks) rely on having a good seal with the wearer's face. `Fit
testing' is, therefore, a critical component to a respiratory protection
program whenever HCWs use tight-fitting respirators. Additionally,
tight-fitting respirators, including the N95, require a user seal check
each time one is put on. In simulation studies, surgical masks had poor
face fit and in vivo filtration efficiency compared with N95 masks and
N99 masks.\textsuperscript{12 13}

\textbf{Use of Gloves}

With regard to hand covering, although wearing gloves was associated
with a lower risk of infection with SARS in some studies (70.2\% and
67.3\% of subjects wearing gloves),\textsuperscript{7 8} results have
been conflicting (47.6\% and 37\% of subjects wearing
gloves).\textsuperscript{10 14} The difference may be caused by the
different proportion of HCWs using gloves. A case-control study included
758 HCWs who cared for SARS patients and found that wearing two layers
of gloves (`double gloving') had a significantly enhanced protective
effect compared with wearing a single layer of gloves. Double gloving
serves two roles: firstly, it acts as an additional membrane should
there be a breach (Using differently coloured gloves for the outer
gloves may allow rapid identification of any breaches in glove
integrity). Secondly, it reduces the spread of viral droplets during
doffing of PPE.\textsuperscript{15} However no such additional
protective effect was found in wearing double layers of gowns,
multi-layered cotton masks, and head and foot
coverings.\textsuperscript{16}

\textbf{PPE and COVID-19}

We have not found any human studies about the protective effect of
different forms of PPE used by HCWs exposed to COVID-19 including the
use of visors. Evidence specifically around PPE and protection from
Covid-19 is at the level of anecdotal reports only. Therefore all the
practice in health care systems across the world is being informed by
evidence from previous epidemics.

\textbf{The population as a whole}

In 2011, a systematic review explored whether physical interventions
could reduce the transmission of respiratory viruses. They found that
frequent handwashing, plus wearing gloves, gowns and masks could reduce
the spread. Evidence was insufficient to support screening at entry
ports or keeping social distancing to reduce respiratory infections
spread.\textsuperscript{17} This is potentially an important piece of
evidence in terms of how COVID-19 virus person to person spread is
managed from here in the population at large.

\textbf{Summary}

The degree of protection required in looking after people with COVID-19
infection, is dependent on the particular environment to which the HCW
is exposed. Covering more of the body could provide better protection
for HCWs. However, the degree of protection required is dependent on the
particular environment. Of importance, it is not just the provision of
PPE but the skills in donning and doffing of PPE that are important,
this being a key time for potential transmission of pathogen to the HCW
and in due time from them to others.

As the first wave of the COVID-19 pandemic abates gradually, surely now
is the time for an urgent review of what PPE should be used to decrease
COVID-19 transmission, based on the evidence to date from health systems
that have dealt with the first wave of the pandemic.

1. The Lancet. COVID-19: protecting health-care workers. \emph{The
Lancet} 2020;395(10228):922. doi:
https://doi.org/10.1016/S0140-6736(20)30644-9

2. O'Sullivan ED. PPE guidance for covid-19: be honest about resource
shortages. \emph{BMJ} 2020;369:m1507. doi: 10.1136/bmj.m1507

3. Verbeek JH, Rajamaki B, Ijaz S, et al. Personal protective equipment
for preventing highly infectious diseases due to exposure to
contaminated body fluids in healthcare staff. \emph{Cochrane Database of
Systematic Reviews} 2020(4) doi: 10.1002/14651858.CD011621.pub4

4. Osei-Bonsu K, Masroor N, Cooper K, et al. Alternative doffing
strategies of personal protective equipment to prevent
self-contamination in the health care setting. \emph{American journal of
infection control} 2019;47(5):534-39. doi: 10.1016/j.ajic.2018.11.003
{[}published Online First: 2018/12/24{]}

5. Poller B, Hall S, Bailey C, et al. `VIOLET': a fluorescence-based
simulation exercise for training healthcare workers in the use of
personal protective equipment. \emph{Journal of Hospital
Infection}2018;99(2):229-35. doi:
https://doi.org/10.1016/j.jhin.2018.01.021

6. Ma H, Wang H, Fang L, et al. A case-control study on the risk factors
of severe acute respiratory syndromes among health care
workers.\emph{Chinese Journal of Epidemiology} 2004;25(9) {[}published
Online First: 20041130{]}

7. Ying W, Gao L, Lin w, et al. Effectiveness of personal protective
measures in prevention of nosocomfal transmission of severe acute
respiratory syndrome. \emph{Chinese Journal of Epidemiology} 2004;25(1)
{[}published Online First: 20040430{]}

8. Zou Y, chen S, Gao Y, et al. Protective Measures to Medical Personnel
and Their Effectiveness in SARS Prevention During the SARS Outbreak in
Guangdong Province. \emph{Chinese Journal of Nosocomiology} 2004;14(4)
{[}published Online First: 20040730{]}

9. Regulation WH. Strengthening health security by implementing the
International Health Regulations (2005).

10. Seto WH, Tsang D, Yung RW, et al. Effectiveness of precautions
against droplets and contact in prevention of nosocomial transmission of
severe acute respiratory syndrome (SARS).
\emph{Lancet}2003;361(9368):1519-20. doi: 10.1016/s0140-6736(03)13168-6
{[}published Online First: 2003/05/10{]}

11. Wang B, Lu H, Shen Y, et al. Development of personal protection
techniques in China from SARS to Ebola virus disease
epidemics.\emph{Chinese Journal of Clinical Infectious Diseases}
2015;8(3) {[}published Online First: 20160204{]}

12. Derrick JL, Gomersall CD. Protecting healthcare staff from severe
acute respiratory syndrome: filtration capacity of multiple surgical
masks. \emph{Journal of Hospital Infection} 2005;59(4):365-68. doi:
https://doi.org/10.1016/j.jhin.2004.10.013

13. Wen Z, Yu L, Yang W, et al. Assessment the protection performance of
different level personal respiratory protection masks against viral
aerosol. \emph{Aerobiologia (Bologna)} 2013;29(3):365-72. doi:
10.1007/s10453-012-9286-7 {[}published Online First: 2012/12/23{]}

14. Teleman MD, Boudville IC, Heng BH, et al. Factors associated with
transmission of severe acute respiratory syndrome among health-care
workers in Singapore. \emph{Epidemiol Infect} 2004;132(5):797-803. doi:
10.1017/s0950268804002766

15. Casanova LM, Rutala WA, Weber DJ, et al. Effect of single- versus
double-gloving on virus transfer to health care workers' skin and
clothing during removal of personal protective equipment. \emph{American
journal of infection control} 2012;40(4):369-74. doi:
10.1016/j.ajic.2011.04.324 {[}published Online First: 2011/08/13{]}

16. Chen W-Q, Ling W-H, Lu C-Y, et al. Which preventive measures might
protect health care workers from SARS? \emph{BMC Public
Health}2009;9:81-81. doi: 10.1186/1471-2458-9-81

17. Jefferson T, Del Mar CB, Dooley L, et al. Physical interventions to
interrupt or reduce the spread of respiratory viruses. \emph{Cochrane
Database of Systematic Reviews} 2011(7) doi:
10.1002/14651858.CD006207.pub4

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