Key words:
SARS-CoV-2, healthcare workers, COVID-19 vaccine
INTRODUCTION
The ongoing pandemic of the coronavirus disease 2019 (COVID-19) caused
by the novel severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) has had significant impact worldwide. Healthcare workers
(HCWs) are considered to be at high risk of exposure to SARS-CoV-2 both
in the community and in the workplace and may play a critical role,
especially when asymptomatic, in the transmission of the infection
within the workplace (both to their patients and co-workers) as well as
in the community1.
Preventing SARS-CoV-2 infection among HCWs is critical to ensure safety
for both patients and HCWs, to contain the ongoing pandemic, and to
maintain a functioning healthcare system.
Many preventive measures have been implemented throughout the pandemic
to contain the spread of the SARS-CoV-2 infection in healthcare
settings, including universal masking, enhanced hand hygiene and
personal protective equipment (PPE) training, symptom screening, and
self-isolation of HCWs if symptomatic or in the case of close contact
with an infected person. Notably, there has been a paradigm shift in the
infection control practices against respiratory infections, which
includes widespread testing of patients and HCWs, including asymptomatic
individuals2,3.
Universal testing of HCWs enabled the prompt identification of
asymptomatic and presymptomatic individuals, determined the
effectiveness of control measures, and helped prevent transmission to
patients and co-workers1,4,5.
Furthermore, COVID-19 vaccines were developed to overcome the pandemic.
Following the implementation of COVID-19 vaccines, HCWs were among the
first prioritised for vaccination in many countries, including Poland.
Data from the placebo-controlled randomized phase 3 clinical trial of
the Pfizer-BioNTech BNT162b2 vaccine showed 95% efficiency in
preventing symptomatic SARS-CoV-2 infection6. Benefits
similar to those observed in clinical trials were also observed in
real-world conditions7.
There is limited data on the incidence of SARS-CoV-2 infection among
HCWs beyond the second wave of the pandemic, and limited data on the
incidence of infection before and after the implementation of the
vaccination programme, especially for European
countries8. So far, most studies performed in Poland
were voluntary seroprevalence studies in small cohorts of HCWs, so the
representativeness of the results obtained may be
limited9,10.
Knowing the factors associated with SARS-CoV-2 infection in HCWs informs
preventive measures and improves the protection of HCWs and patients.
To further explore factors associated with SARS-CoV-2 infection, we
retrospectively analysed the large real-world testing database obtained
between October 20, 2020, and August 31, 2021, at The Children’s
Memorial Health Institute (CMHI), a tertiary paediatric hospital in
Warsaw. In this setting, 2,332 HCWs participated in the universal
screening programme for early identification of the SARS-CoV-2
infection. The aim of the study was to analyse the incidence of new
SARS-CoV-2 infections among HCWs (before and after vaccination with
BNT162b2) and to explore the demographics and work-related factors
associated with SARS-CoV-2 infection. We also attempted to assess the
vaccine effectiveness in a real-world setting.
METHODS: