Introduction
Consistent with World Health Organization (WHO) advice [1], UK Infection Protection Control guidance recommends that healthcare workers (HCWs) caring
for patients with coronavirus disease 2019 (COVID-19) should use fluid
resistant surgical masks type IIR (FRSMs) as respiratory protective
equipment (RPE), unless aerosol generating procedures (AGPs) are being
undertaken or are likely, when a filtering face piece 3 (FFP3)
respirator should be used [2]. In a recent update, an FFP3
respirator is recommended if “an unacceptable risk of transmission
remains following rigorous application of the hierarchy of control”
[3]. Conversely, guidance from the Centers for Disease Control and
Prevention (CDC) recommends that HCWs caring for patients with COVID-19
should use an N95 or higher level respirator [4]. WHO guidance
suggests that a respirator, such as FFP3, may be used for HCWs in the
absence of AGPs if availability or cost is not an issue [1].
A recent systematic review undertaken for PHE concluded that: “patients
with SARS-CoV-2 infection who are breathing, talking or coughing
generate both respiratory droplets and aerosols, but FRSM (and where
required, eye protection) are considered to provide adequate staff
protection” [5]. Nevertheless, FFP3 respirators are more effective
in preventing aerosol transmission than FRSMs, and observational data
suggests that they may improve protection for HCWs [6]. It has
therefore been suggested that respirators should be considered as a
means of affording the best available protection [7], and some
organisations have decided to provide FFP3 (or equivalent) respirators
to HCWs caring for COVID-19 patients, despite a lack of mandate from
local or national guidelines [8].
Data from the HCW testing programme at Cambridge University Hospitals
NHS Foundation Trust (CUHNFT) during the first wave of the UK severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic indicated
a higher incidence of infection amongst HCWs caring for patients with
COVID-19, compared with those who did not [9]. Subsequent studies
have confirmed this observation [10, 11]. This disparity persisted
at CUHNFT in December 2020, despite control measures consistent with PHE
guidance and audits indicating good compliance. The CUHNFT infection
control committee therefore implemented a change of RPE for staff on
“red” (COVID-19) wards from FRSMs to FFP3 respirators. In this study,
we analyse the incidence of SARS-CoV-2 infection in HCWs before and
after this transition.