Evaluation of real and perceived risk to health care workers caring for patients with the Omicron variant of the SARS-CoV-2 virus in surgery and obstetrics

Abstract

Introduction
The Omicron variant of the SARS-CoV-2 virus is described as more contagious than previous variants. We sought to assess risk to healthcare workers (HCWs) caring for patients with COVID-19 in surgical/obstetrical settings, and the perception of risk amongst this group.

Methods
From January to April, 2022, reverse transcription polymerase chain reaction was used to detect the presence of SARS-CoV-2 viral RNA in patient, environmental (floor, equipment, passive air) samples, and HCW’s masks (inside surface) during urgent surgery or obstetrical delivery for patients with SARS-CoV-2 infection. The primary outcome was the proportion of HCWs’ masks testing positive. Results were compared with our previous cross-sectional study involving obstetrical/surgical patients with earlier variants (2020/21). HCWs completed a risk perception electronic questionnaire.

Results
11 patients were included: 3 vaginal births and 8 surgeries. 5/108 samples (5%) tested positive (SARS-CoV-2 Omicron) viral RNA: 2/5 endotracheal tubes, 1/22 floor samples, 1/4 patient masks and 1 nasal probe. No samples from the HCWs masks (0/35), surgical equipment (0/10) and air samples (0/11) tested positive. No significant differences were found between the Omicron and 2020/21 patient groups’ positivity rates (Mann-Whitney U test, p = 0.838) or the level of viral load from the nasopharyngeal swabs (p = 0.405). Nurses had a higher risk perception than physicians (p = 0.038).

Conclusion
No significant difference in contamination rates were found between SARS-CoV-2 Omicron BA.1 and previous variants in surgical/obstetrical settings. This is reassuring as no HCW mask was positive and no HCW tested positive for COVID-19 post-exposure.

Full text

Evaluation of real and perceived risk to health care workers caring for patients with the
Omicron variant of the SARS-CoV-2 virus in surgery and obstetrics
Authors:
Chaithanya Nair, BSc1, Robert Kozak PhD2, Nasrin Alavi MD3, Hamza Mbareche PhD3, Rose C.
Kung MD, MSc4, Kellie E. Murphy MD, MSc5, Darian Perruzza MD1,3, Stephanie Jarvi BHSc1,3,
Elsa Salvant HBSc3, Noor Niyar N. Ladhani MD, MPH6, Albert J.M. Yee MD, MSc7, Louise-
Helene Gagnon MD CM, MScCH4, Richard Jenkinson MD, MSc7, Grace Y. Liu MD, MSc4,
Patricia E. Lee MD CM, LLM4
Corresponding Author:
Patricia E. Lee, B732-2075 Bayview Avenue, Toronto, ON, M4N 3M5 pel.lee@utoronto.ca
Affiliations:
1 Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
2 Division of Microbiology, Department of Medicine, Sunnybrook Health Sciences Centre,
University of Toronto, Toronto, Ontario, Canada
3 Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto,
Toronto, Ontario, Canada
4 Divisions of Urogynecology and Minimally Invasive Gynecologic Surgery, Department of
Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, University of Toronto,
Toronto, Ontario, Canada
5 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Sinai Health
System, University of Toronto, Toronto, Ontario, Canada
6 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook
Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
7 Division of Orthopedics & Trauma Surgery, Department of Surgery, Sunnybrook Health
Sciences Centre, University of Toronto, Toronto, Ontario, Canada
Funding Sources:
This study was supported by the Sunnybrook AFP Association through the Innovation Fund of
the Alternative Funding Plan for the Academic Health Sciences Centres of Ontario (Lee) and a
CREMS summer research student award from the Temerty Faculty of Medicine, University of
Toronto (Nair).
The funders had no role in the design and conduct of the study; collection, management,
analysis and interpretation of the data; preparation, review, or approval of the manuscript; and
decision to submit the manuscript for publication.
Declaration of authors: No disclosures or conflicts of interest are reported.
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NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.

Abstract
Introduction
The Omicron variant of the SARS-CoV-2 virus is described as more contagious than previous
variants. We sought to assess risk to healthcare workers (HCWs) caring for patients with
COVID-19 in surgical/obstetrical settings, and the perception of risk amongst this group.
Methods
From January to April, 2022, reverse transcription polymerase chain reaction was used to detect
the presence of SARS-CoV-2 viral RNA in patient, environmental (floor, equipment, passive air)
samples, and HCW’s masks (inside surface) during urgent surgery or obstetrical delivery for
patients with SARS-CoV-2 infection. The primary outcome was the proportion of HCWs’ masks
testing positive. Results were compared with our previous cross-sectional study involving
obstetrical/surgical patients with earlier variants (2020/21). HCWs completed a risk perception
electronic questionnaire.
Results
11 patients were included: 3 vaginal births and 8 surgeries. 5/108 samples (5%) tested positive
(SARS-CoV-2 Omicron) viral RNA: 2/5 endotracheal tubes, 1/22 floor samples, 1/4 patient
masks and 1 nasal probe. No samples from the HCWs masks (0/35), surgical equipment (0/10)
and air samples (0/11) tested positive. No significant differences were found between the
Omicron and 2020/21 patient groups’ positivity rates (Mann-Whitney U test, p = 0.838) or the
level of viral load from the nasopharyngeal swabs (p = 0.405). Nurses had a higher risk
perception than physicians (p = 0.038).
Conclusion
No significant difference in contamination rates were found between SARS-CoV-2 Omicron
BA.1 and previous variants in surgical/obstetrical settings. This is reassuring as no HCW mask
was positive and no HCW tested positive for COVID-19 post-exposure.
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Background
The Omicron variant of the SARS-CoV-2 virus has been reported to be more contagious than
the previously encountered variants1,2. It contains numerous mutations in the spike protein
allowing the virus to evade neutralizing antibodies 1-4. As a result, following 2 doses, vaccine
efficacy at preventing infection was shown to be decreased to 70%, which is notably lower than
has been reported against other variants5. Due to its high rate of transmission and reduced
effectiveness of existing vaccines at preventing infection, the risk that the Omicron variant of the
SARS-CoV-2 virus poses to healthcare workers (HCWs) in close contact with infected
individuals is a topic of concern.
Surgery and obstetrics involve close and prolonged contact with patients. Transmission of the
SARS-CoV-2 virus occurs primarily through respiratory droplets, aerosols and contact with
contaminated surfaces6,7. However, the risk of HCWs contracting Omicron variant of the SARS-
CoV-2 through respiratory droplets in an obstetrical or surgical setting is unclear. Besides the
respiratory tract, the SARS-CoV-2 virus has also been shown to be present in the GI tract,
amniotic fluid, peritoneal fluid and vaginal fluid8-14. For surgeries/procedures that involve these
structures or substances, the risk of transmission through aerosolization of viral particles from
the surgical site is unclear. Transmission can also occur by coming into contact with
contaminated surfaces6,7. It is unclear whether HCWs involved in a surgery or an obstetrical
delivery are at risk of being infected with the Omicron variant of the SARS-CoV-2 virus in such a
manner.
HCWs’ perception of safety in their work environments has been investigated, particularly during
the early stages of the pandemic15-19. Previous studies conducted around the world have
indicated that personal protective equipment (PPE) shortage, insufficient protection provided by
the PPE and fear of infection have all contributed to HCWs feeling unsafe at their workplaces15-
19. However, whether these sentiments are shared by HCWs in Canada during more recent
waves of the pandemic is not known.
In general, the risk to health care workers caring for patients infected with the Omicron variant in
surgical and obstetrical settings is unclear. The aim of this study is to determine the risk
associated with exposure to Omicron variant of the SARS-CoV-2 virus in the operating room or
obstetrical delivery setting and whether this risk is higher in comparison to previous variants.
Further, we also seek to explore HCWs’ perception of risk at their workplace and their attitudes
towards the PPE provided.
Methods
Study Design
A cross-sectional study was conducted from January 2022 to April 2022. Patients with a
nasopharyngeal (NP) or mid-turbinate swab positive for SARS-CoV-2 by real-time reverse
transcription polymerase chain reaction (RT-PCR), in need of urgent surgery or obstetric
delivery at Sunnybrook Health Sciences Centre, were prospectively identified by the surgical or
obstetric clinical teams. Urgent surgery, as per Sunnybrook’s operating room policies, was
defined as 1A, 1B, 1C and 1D: surgery required within 2 hours, 2–8 hours, 8–48 hours and 2–7
days, respectively, to avoid harm to patients20. The Strengthening the Reporting of
Observational Studies in Epidemiology (STROBE) checklist was used to report this study21.
2020-21 Study group14
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A cross-sectional study was conducted from November 2020 to May 2021 at 2 tertiary academic
Toronto hospitals (Sunnybrook Health Sciences Centre and Sinai Health System), during urgent
surgeries or obstetric deliveries for 32 patients with SARS-CoV-2 infection. The presence of
SARS-CoV-2 viral RNA in patient, environmental and air samples was identified by real-time
reverse transcription polymerase chain reaction (RT-PCR).
Results of the 2020-21 Study group were compared with the current study 2022 Omicron
group.
Setting (2022)
Patients were recruited from Sunnybrook Health Sciences Centre, a level 3 obstetrical unit and
a tertiary care regional trauma and burn centre.
Standard hospital procedures and PPE worn by health care workers attending patients with
SARS-CoV-2 infection included the following: disposable protective head covering, mask (either
N95 mask or American Society for Testing and Materials [ASTM] level 3 surgical mask), face
shield or eye protection, impermeable gown, gloves, and shoe or boot covers. When possible,
contaminated PPE was removed in the adjacent anteroom of the operating room. During
intubation and extubation, only the anesthesia team (with N95 masks) remained in the room.
N95 mask fit testing was a requirement of hospital health care workers in the surgical and
obstetric clinical areas. If able, patients wore ASTM level 3 ear loop masks. All the operating
rooms (including those in the birthing area) were equipped with 20 air exchanges per hour.
Participants
Patients were included if they were at least 18 years of age; were within 30 days of a positive
nasopharyngeal swab for SARS-CoV-2 (either asymptomatic or symptomatic for COVID-1922) or
were beyond 30 days from an initial positive nasopharyngeal swab for SARS-CoV-2 and still
had symptoms of COVID-19, and required obstetrical delivery or urgent surgery.
Health care workers included any consenting health care workers present in the operating or
delivery room, caring for the patient.
Data Sources
Information about the patient’s history and presenting problem was extracted from the patient
electronic medical records (EMR).
Study Procedures
Study procedures are described in detail in Appendix 1. Patient sampling for abdominal surgical
cases included peritoneal cavity fluid (male or female). Patient samples for obstetrical cases
included vaginal fluid and swabs of the membranous placenta.
Equipment and environmental samples included swabs of the room floor (within 1 m from the
surgical site, and 2 m away from the surgical site23), swab of equipment (e.g., endotracheal tube
and surgical instruments), and swab of the inside of the surgical mask worn by health care
workers24-26
Passive air sampling was performed using an open Petri dish to collect any viral particles
settling by gravity in the dish (within 1–2 m of the patient, 1 m off the floor)25,27-30.
Laboratory processes
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All samples were processed at Sunnybrook Health Sciences Centre and the laboratory staff
were blinded to the source of the sample.
Virus detection was performed by real-time RT-PCR using a multitarget assay31.
The viral RNA
loads from samples were extracted using the EasyMag Platform (bioMérieux
, France) according
to the manufacturer’s instructions. Detection of the SARS-CoV-2 viral RNA was performed using
the Luna Universal Probe One-Step RT- qPCR Kit (New England Biolabs, Canada) with the
primers and probe for the E-gene, and the thermocycling conditions that have been described
by Corman and colleagues32 on the Rotor-Gene Q platform (Qiagen, Germany).
The cycle threshold (Ct) value of the assay was used as an estimate of the viral load and was
obtained for all samples where possible, including values from the patient’s initial diagnostic
swab. Samples were considered negative if the Ct value was 40 or greater.
Survey of HCWs
HCWs who consented to have their mask swabbed and tested were contacted via email once
within 6 weeks of the procedure and invited to participate in an electronic survey via LimeSurvey
(Appendix 2). This 7-10 question survey assessed the HCWs’ experience of caring for a patient
with a NP swab positive for COVID-19. HCWs were asked to indicate how safe they felt with the
PPE provided on a Likert scale of 1(not safe at all) to 10 (very safe). The survey also included
questions about whether any COVID-19 symptoms were experienced after the patient
encounter, any COVID-19 testing they undertook after the procedure, and their vaccination
status. The same survey was distributed in 2021 to HCWs who participated in an earlier study14,
caring for NP swab positive patients between November 2020 to May 2021 approximately 4-6
months after their exposure.
Statistics
Not all patients had similar data as there were different clinical scenarios. Descriptive statistics
were generated using Microsoft Excel (Version 16.62) for: age of the patients, Ct values of the
nasopharyngeal swabs and the survey results. Further, the Mann-Whitney U test was performed
using R (Version 4.2.1, 2021) to: compare NP swab Ct values of patients with a positive RT-
PCR study sample and patients with no positive study sample, and NP swab Ct values of
patients with the Omicron variant of the SARS-CoV-2 virus and other patients with other
previous variants (from the 2020-21 Study group)14. The HCW survey results from different
groups of HCWs (e.g. physicians, nurses,) were also compared using the Mann-Whitney U test.
The 2-sample test for equality of proportions was used to compare the sample positivity rate in
the current study group and the 2020-21 study group. Additionally, the Shapiro-Wilk test was
used to assess for normality at all times before using the Mann Whitney U tests.
Outcomes
The primary outcome was the proportion of health care workers’ mask samples with positive
SARS-CoV-2 RNA RT-PCR results. Other outcomes included the rate of SARS- CoV-2 RNA
PCR-positive samples from the surgical site (relevant patient samples), surgical equipment,
floor, and ambient air of the operating room or birthing room. Additionally, as described in the
“Laboratory processes” section, the Ct value was obtained for all positive samples where
possible. For the HCW survey, main outcomes of interest included number of HCWs who
contracted COVID-19 as a result of the exposure in the operating room or birthing room, and
how safe they felt with the PPE provided.
Ethics Approval
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The Sunnybrook Research Ethics Board granted ethics approval (#1676).
Patient samples (peritoneal fluid, vaginal, or placental swabs) were collected in patients
providing informed consent. Mask sampling of attending health care workers was performed
with health care workers’ consent. Patient or health care worker consent was not required for
sampling from the air, floor, or surgical instruments. Consenting health care workers agreed to
follow up with hospital occupational health departments if SARS-CoV-2 RNA was detected on
the inside surface of their mask, and also agreed to participate in an online survey emailed to
them after the patient encounter.
Results
Description of the cohort
Eleven patients at Sunnybrook Health Sciences Centre were recruited for the study, five were
male and six were female (mean age 43.8 years, standard deviation 14.9). Three of the patients
had vaginal deliveries, while the other eight underwent urgent surgery. A nasopharyngeal swab
testing for SARS-CoV-2 was performed on all patients in this study at a median of 3 days before
their procedure (mean 4.63, range 1-16). Two patients underwent a repeat nasopharyngeal
swab on the day of their procedure. The vaccination status for 10/11 of the patients was known.
Three of the patients received three doses of the COVID-19 vaccination; 5 patients received two
doses of the COVID-19 vaccinations and 2 were unvaccinated.
Detection of SARS-CoV-2 in surgical and environmental samples
A total of 108 samples were collected (Table 1). Five of 108 samples were duplicates
(endotracheal tube sampled using two different methods). All samples were tested for the
presence of the SARS-CoV-2 virus and five out of the 103 samples (5%) tested positive: 2 out
of 5 endotracheal tubes (2 urgent surgery cases), 1 out of 22 floor samples (1 neurosurgery
case, sample from at least 2 metres away from the bed) and 1 nasal temperature probe sample
(Burn Surgery case). A swab taken from the inside of 1 patient’s mask was positive (vaginal
birth). None of the samples from the HCWs masks (0/35), surgical equipment (0/10) and Petri
dishes (0/11) tested positive. In the 2020-21 study group, 20/332 samples (6%) had tested
positive for SARS-CoV-2 RNA. No significant differences were found between the sample
positivity rates of this Omicron study group and the 2020-21 study group of earlier SARS-CoV-2
variants/subtypes (2 sample test for equality of proportions, p-value = 0.838)
Viral Load in Patient Samples
During our study period of January to April 2022, the SARS-CoV-2 variant isolated in the
Sunnybrook Microbiology Lab was only Omicron BA.1. For 7/11 patients in this study, Ct values
were obtained from the nasopharyngeal swabs that were collected (mean = 30.13, range 17.32
– 39.57). Comparing the NP swab Ct values of the 4 patients with any positive study sample (of
surgical equipment, environment) and the 3 patients with no positive study sample, there were
no significant differences found between the two groups (Mann-Whitney U test, p = 0.114).
NP swab Ct values were also collected for the 2020-21 study group, consisting of 32 patients
with previous variants of the SARS-CoV-2 virus (mean = 26.95, range 11.86 – 37.25)14. When
compared with NP swab Ct values of patients with the Omicron variant, no significant difference
was found between these two groups of patients (Mann-Whitney U test, p = 0.405).
HCW Survey
A total of 45 responses were recorded for the survey for a total of 70 patient case encounters
(with a HCW potentially having more than one patient encounter): 13 nurses, 29 physicians
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(surgeons, anesthetists, or their house staff) and 3 respiratory technician/anesthesia assistants.
Of the 45 HCWs, 32 are from the time period of Nov 2020-May 2021 (the 2020-21 group) and
13 are from the period of January -April 2022 (the 2022 Omicron group). The survey response
rate was 37% (29/78) for the 2020-21 group and 48% (13/27) for the 2022 Omicron group.
Three of 45 HCWs arranged for COVID-19 testing within 2 weeks after the clinical exposure: 1
was worried about the exposure (2020-21 group), 1 had symptoms (2020-21 group) and 1 was
asymptomatic but arranged for testing due to upcoming planned travel (2022 Omicron group).
All 3 tests were reported as negative. Zero of 45 HCWs reported being ill with COVID-19 within
2 weeks after clinical exposure. Two of 45 HCWs reported not being vaccinated at the time of
clinical exposure (2020-21 group); 8/45 had 1 vaccination dose and all others (35/45) had at
least 2 doses of COVID-19 vaccine. HCWs were asked to indicate on a Likert scale of 1 (not
safe at all) to 10 (very safe) how safe they felt with the PPE provided. The average score was
8.066 (range 3-10). There was a significant difference between the scores given by physicians
(mean 8.69 +/-1.54) and nurses (mean 6.92 +/- 2.43), Mann U Whitney p-value = 0.0377, Table
2 and Figure 1. Sixty-five percent (19/29) of physicians indicated 9 or 10 on the Likert scale for
how safe they felt with the PPE they were provided compared to 31% (4/13) of nurses who
responded 9 or 10.
Discussion
In the era of COVID-19, the safety of HCWs involved in surgery and obstetrics is paramount due
to the prolonged and close contact they have with potentially infected patients. We found no
difference in contamination rate in the operating room and birthing room settings between this
study’s Omicron BA.1 group of 11 patients and our previous study group of 32 patients from
2021-21, representing a cohort infected with previous variants of concern.
With this study, none (0/35) of the swabs collected from the inside surface of HCW masks
tested positive for the SARS-CoV-2 viral RNA. This is similar to the results from our 2020/2021
study group, which had also found no evidence of viral RNA on the inside surface of HCWs’
masks14. Brandner et. al also found no contamination of masks in HCWs that attended
autopsies: they assessed contamination of PPE during autopsies of COVID-19 patients and
reported that samples from gloves, aprons and tops of shoes worn by HCWs tested positive for
the SARS-CoV-2 viral RNA33. Infectious virus was isolated from 21% of the RNA-positive glove
samples (3/11 full autopsies)33. Similar to surgery/obstetrics, autopsies may require close and
prolonged contact with body fluids and secretions and consequently the aforementioned
findings of PPE contamination may also be applicable to surgical or obstetrical settings. Thus, it
is important to consider that while the samples from the masks of HCWs had tested negative, a
risk of transmission still remains.
Out of the 108 samples that were tested for this study, five study samples tested positive (5%).
Among the samples that tested positive are 2 endotracheal tubes (ETT) samples and 1 nasal
temperature probe sample. The positivity of the ETT and nasal probe samples can be attributed
to the presence of SARS-CoV-2 in the respiratory tract7,22,34,35. The inside surface of one patient
mask tested positive (obstetrical patient).The positive floor swab is consistent with studies
conducted in the ICU that have reported contamination of the air and surfaces within about 4m
from patients infected with SARS-CoV-236. Further, these findings are comparable to that of the
2020/2021 study group where 8 of 12 ETT samples and 5 out of 60 floor samples tested
positive14.
Passive air sampling in this current study using the petri dish did not yield any positive results. A
study by Schoen et. al investigating the presence of viral RNA in the air in the labor room with
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un-vaccinated patients who had tested positive for SARS-CoV-2 had also failed to detect the
viral RNA in the air37. However, in our previous study, 1of 7 passive air samples in the operating
room had tested positive for the SARS-CoV-2 RNA14. Also, de Man et. al that found 4 in 17 air
samples of the Intensive Care Unit (ICU) to be positive for SARS-CoV-238.
None of the surgical equipment samples for this study had tested positive (other than ETT,
nasal probe), whereas, in our previous study, 2 of 11 samples from surgical equipment
(scissors, clamps) had tested positive14 . These low sample positivity rates align with findings of
a study by Fabbri et.al that indicate that the transmission risk during surgery, specifically
through aerosolization from the surgical field, is low39.
Generally, the contamination rates observed for the Omicron variant (5%) in this study and the
previous variants (6%) from our previous study have been quite similar. There was no
significant difference in the NP swab Ct values between these two groups which would indicate
that the viral load is not higher with one group compared to the other, although this may also be
due to the small sample sizes. Glirnet et al also found no significant difference in contamination
rates between the original, Alpha and Omicron strains of the SARS-CoV-2 virus in a COVID-19
patient ward setting: environmental samples from a hospital isolation ward and a quarantine
hotel during February 2021 for the Alpha and original variants and in January 2022 for the
Omicron variant40. Although we did find in our previous study that higher viral load (lower NP Ct
value) was associated with a higher risk of contamination14, we did not demonstrate a similar
finding with this Omicron study, which may have been due to the smaller number of patients
studied.
In our study with 3/45 HCWs arranging for testing after the exposure, it can be inferred these
HCWs generally perceived their work environment to be safe. Further, most of the survey
respondents in both the 2020/21 group and the 2022 Omicron group indicated that they felt safe
with the PPE they were provided. This contrasts with the results of the previous studies
reporting low HCW satisfaction with PPE provided and safety at work15-19. In a study that was
conducted in Qatar from June 2020 to July 2020, Ismail et. al reported that only 45.6% of HCWs
surveyed were satisfied or highly satisfied with the quality of the PPE provided to them16.
Similarly, a study by Aloweni et. al conducted in Singapore from July 2020 to September 2020
also found that only 13.7% of the participating HCW were ‘highly confident’ of the protection
provided by the PPE17. However, the measures used to evaluate “feeling safe” or “satisfaction
with” or “being confident” with the PPE used in these studies were different, and it is also
important to keep in mind that these studies took place in different countries during a different
time period when PPE shortage could have been possibly a more pertinent issue15-19.
Interestingly, in our HCW survey we found a significant difference between nurses and
physicians in terms of how safe they felt with the PPE they were provided. Nurses had
responded with lower scores compared to physicians with 54% of nurses compared to 25% of
physicians scoring 7 or lower to indicate how safe they felt with the PPE provided. It is possible
that being involved in caring for the patient for longer time periods and spending more time in
the operating room and birthing room environment may have all contributed to these lower
scores.
Limitations
This study has limitations. Firstly, the study size is small; therefore, it is possible that the results
cannot be generalized to the rest of the population with the Omicron variant of the SARS-CoV-2
virus. Further, due to limitations of testing procedure and equipment, it is possible that the
presence of the SARS-CoV-2 virus may not have been detected in certain samples. It is also
recognized that capturing positive air samples may be challenging41. In the future, studies can
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be conducted to further quantify the risk to HCWs caring for patients in a surgical or obstetrical
setting by looking for and documenting the presence of infection amongst HCW post-exposure.
The HCW survey response may have been higher with frequent email reminders.
Conclusion
Despite the Omicron variant being described as more contagious, there does not appear to be
an increased risk of SARS-COV-2 viral RNA contamination in the operating room or birthing
room environment with the Omicron BA.1 variant compared to earlier subtypes and variants of
concern.
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Table 1: Table 1: Clinical Case Details and Results of Samples Obtained
ID
no.
Age
Range
(years)
†
S
e
x
No. of
days
from
first
SARS-
CoV-2
Positive
Test to
Proced
ure
(repeat
test)§
COVID-19
Associated
Symptoms
Surgical service:
Procedure
Performed
Ct value
of initial
NP swab
Positive
Samples
Obtained (Ct
Values)
Negative Samples
1
30-39
F
8(0)
Cough
Obstetrics:
Vaginal Delivery
26.45
Patient mask
(swab of
inside
surface)
(36.67)
Placenta, vaginal
fluid, surgical
equipment, Petri
dish, HCW masks,
floor <1m and 2m
2
50-59
F
7(0)
Asymptom
atic
Neurosurgery:
Left Craniotomy
for tumor
resection
24.91
ETT swab
(31.01),
Floor swab
more than
2m away
from
patient’s bed
(38.39)
Surgical
equipment, Petri
dish, HCW masks,
floor <1m and 2m
3
30-39
F
2
Asymptom
atic
Obstetrics:
Vaginal Delivery
36.32
none
Placenta, surgical
equipment, Petri
dish, HCW masks,
floor <1m and 2m
4
30-39
F
16
Persistent
Cough
Obstetrics:
Vaginal Delivery
39.57
none
Placenta, surgical
equipment, Petri
dish, HCW masks,
patient mask, floor
<1m and 2m
5
60-69
F
2
Asymptom
atic
Neurosurgery:
Laminectomy
for excision of
intradural
extramedullary
tumor
n/a
none
ETT, surgical
equipment, Petri
dish, HCW masks,
patient mask, floor
<1m and 2m
6
40-49
M
1
Asymptom
atic
Orthopedic
Surgery:
n/a
none
ETT, surgical
equipment, Petri
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Open reduction
and internal
fixation (ORIF)
of left intra-
articular distal
femur fracture
dish, HCW masks,
floor <1m and 2m
7
30-39
M
1
Asymptom
atic
Orthopedic
Surgery:
Left ulna
irrigation and
debridement
and ORIF, Left
thigh I &D and
closure, Left
knee I &D and
closure
arthrotomy, Left
tibia I & D and
intermedullary
nailing, Left
distal femur
traction pin
insertion
n/a
none
Surgical
equipment, Petri
dish, HCW masks,
floor <1m and 2m
8
60-69
F
3
Asymptom
atic
Orthopedic
Surgery:
ORIF for both
column
acetabular
fracture and
hardware
implanted,
removal of
traction/externa
l fixation device
30.98
none
ETT, surgical
equipment, Petri
dish, HCW masks,
floor <1m and 2m
9
60-69
M
6
Asymptom
atic
Cardiac Surgery:
Coronary Artery
Bypass
n/a
none
Transesophageal
echo probe,
surgical
equipment, Petri
dish, HCW masks,
patient mask, floor
<1m and 2m
10
30-39
M
3
Asymptom
atic
Burn Surgery:
Debridement of
Fournier’s
Gangrene
35.37
Nasal Probe
swab (33.94)
U/S Probe, Nasal
Probe, surgical
equipment, Petri
dish, HCW masks,
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patient mask, floor
<1m and 2m
11
20-29
M
2
Asymptom
atic
General
Surgery:
Laparoscopic
Appendectomy
17.32
ETT swab
(17.39)
Peritoneal fluid,
Petri dish, HCW
mask, floor <1m
and 2m
Legend:
†Age range used to preserve anonymity; §test was repeated same day (0 days) as procedure; Ct = cycle threshold; NP =
nasopharyngeal; HCW = health care worker; ETT = endotracheal tube; I & D = incision and drainage
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Table 2: Health care worker Survey after the exposure to a patient infected with SARS-CoV-2
HCW role
No. of
Responses
No. of HCWs
who arranged
to be tested
after the
exposure
No. of HCWs
who
experienced
symptoms
after the
exposure
No. of HCWs
who became
sick with
COVID-19
after the
exposure
Mean score given
for how safe
HCWs felt with
the PPE provided
( SD) [Likert
scale: 1 = felt not
safe at all, 10 =
felt very safe]
Anesthesia
Assistant
2
0
0
0
5.503.54
Respiratory
Technician
1
0
0
0
10†
Nurse
13
1
1
0
6.922.43
Physician
29
2
0
0
8.691.54ǂ
Legend:
HCW = health care worker; PPE = personal protective equipment
†There was only one response for this category, mean not calculated
ǂ20 surgeons (8.5 +/- 1.63), 9 anesthetists (9.11 +/- 1.27), no significant difference
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Figure 2: Personal Protective Equipment (PPE) safety scores
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10
Percentage of Responses (%)
PPE Safety Scores
PPE Safety Scores Provided by Nurses and Physicians
Physicians Nurses
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APPENDIX 1: Supplement for Study Sample Collection
GENERAL DETAILS:
Each dental pledget was pre-moistened with up to 3cc of sterile UTM from a newly opened unused 15cc
sterile Falcon tube containing 3 cc of UTM, universal transport medium (UTM®, Copan Diagnostics, CA,
USA; https://www.copanusa.com/sample-collection-transport-processing/utm-viral-transport/).
Hand hygiene and glove changes were performed between the collection of every sample and the
outside surface of each container was wiped off with a CaviWipesTM towelette
(https://www.metrex.com/en-ca/caviwipes) and then each sample was stored in a separate new
biohazard marked ziploc plastic bag and placed in the fridge at 4ᵒ Celsius within 20 minutes. All collected
samples were processed at the Sunnybrook Microbiology Lab (stored in the interim at -20ᵒ and then -80ᵒ
Celsius).
Samples were analyzed by RT-PCR as previously described (Vermeiren C, Marchand-Senecal X, Sheldrake
E, et al. Comparison of Copan Eswab and FLOQswab for COVID-19 PCR diagnosis: working around a
supply shortage. J Clin Microbiol 2020.)
All the operating rooms (including those in the Birthing area) have 20 air exchanges an hour.
Cycle threshold values (the number of cycles required for the fluorescent signal to cross the threshold in
RT-PCR) quantified viral load, with lower values indicative of a higher viral load.
PATIENT SAMPLES
1) PERITONEAL FLUID SAMPLE:
Taken by a member of the surgical team: 5-10 cc of peritoneal fluid (if present upon entering the cavity),
or, if no fluid seen, 10cc of sterile saline was placed in the peritoneal cavity with a 10cc sterile syringe
and then whatever volume of fluid aspirated back into the syringe was placed in an 80cc sterile plastic
container.
2) VAGINA:
Taken by a member of the obstetrical team: a vaginal speculum was placed in the vagina before delivery
(typically after informed consent and well before active labor) and up to 5 cc of pooled vaginal fluid was
aspirated with a sterile 10cc syringe. If no vaginal fluid was seen, 10cc of sterile saline was placed in the
vagina with a 10cc sterile syringe and then whatever volume of fluid that was aspirated back into the
syringe was placed in an 80cc sterile plastic container.
3) PLACENTA:
Taken by a member of the obstetrical/research team at the end of the case with a flocked swab (iClean,
HCY, Shenzhen, China; https://www.chenyanglobal.com/oropharyngeal-nylon-flocked-swab-product/)
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which was used to wipe the surface of the membranous placenta and the swab was placed immediately
in a 15cc sterile plastic Falcon tube containing 3cc of UTM.
ENVIRONMENTAL SAMPLES
4) FLOOR:
Taken by a member of the research team at the end of the case: a sterile dental pledget (3/8” x 1.5”
cylindrical sponge, SDP Inc. Montreal, Canada; https://www.sdpmedical.com/en/cylindrical-sponges)
was pre-moistened with sterile universal transport media and the floor was swabbed in a location as
close to the patient as permits and also at least 2 metres away. The swabbing was performed in a
standardized fashion over a 30x30cm area with 2 perpendicular “S” swipes. The pledget was placed
immediately in a 15cc sterile plastic Falcon tube containing 3cc of UTM.
5) ENDOTRACHEAL TUBE (ETT):
Taken by a member of the research team at the end of the case after the patient was extubated: a
sterile dental pledget or a flocked swab was pre-moistened with UTM and used to wipe the length of the
distal half of the ETT and the pledget/swab placed immediately in a 15cc sterile plastic Falcon tube
containing 3cc of UTM.
6) SURGICAL INSTRUMENTS / EQUIPMENT:
Taken by a member of the research team at the end of the case: a sterile dental pledget was pre-
moistened with sterile UTM and used to wipe the part of the instrument or equipment that was in direct
contact with the patient’s surgical site. The pledget then placed immediately in a 15cc sterile plastic
Falcon tube containing 3cc of UTM.
7) PASSIVE AIR SAMPLE:
3cc of sterile UTM was placed in a sterile 90mm Petri dish which was placed open by a member of the
research team at the beginning of the case within 1-2 metres of the patient and in a location that would
not interfere with patient care, on a Mayo stand about 1 metre high from the floor. The Petri dish was
retrieved at the end of the case and the UTM in it transferred to a sterile Falcon tube.
8) MASK SAMPLE:
Masks were swabbed on their inside surface by a member of the research team with a sterile dental
pledget that was pre-moistened with UTM – wiping over the inside of the mask twice in the area (up to
10x10cm) that would have been in contact with the nose and mouth. The pledget then placed
immediately in a 15cc sterile Falcon tube containing 3cc of UTM.
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APPENDIX 2: Health care worker Questionnaire (via LimeSurvey)
Q1: How many times did you participate in this COVID-19 study and leave your mask to be tested with a
study team member?
a) 1
b) 2
c) 3
d) 4
e) 5
Q2: Please indicate your role
a) Nurse (including scrub nurse, circulating nurse,
student)
d) Respiratory Technician
b) Physician -anesthesia team member (including
staff, house staff, student)
e) Prefer not to say
c) Physician - surgical team member (including
staff, house staff, student)
f) Other: _______
Q3: Within 2 weeks after you worked with a COVID-19 positive patient in the OR (or birthing unit), did
you arrange to be tested for COVID-19?
a) Yes
b) No (go to Q6)
Q4: Did you arrange to be tested because you were worried about the exposure?
a) Yes
c) Not sure
b) No
Free text option: ________
Q5: Within 2 weeks after you worked with a COVID-19 patient in the OR (or birthing unit), did your
COVID-19 swab/test result return positive for COVID-19
a) Yes
c) Not sure
b) No
Free text option: ________
Q6: Within 2 weeks after you worked with a COVID-19 positive patient in the OR (or birthing unit), did
you develop COVID-19 symptoms?
a) Yes
b) No
Free text option: ________
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Q7: Within 2 weeks after you worked with a COVID-19 positive patient in the OR (or birthing unit), did
you become sick with COVID-19?
a) Yes
b) No (go to Q9)
Free text option: ________
Q8: If you tested positive for COVID-19 or were sick with COVID-19 within 2 weeks after you worked
with a COVID-19 patient in this study, do you think you became COVID-19 positive as a result of this
exposure?
a) Yes
d) I don't know
b) No - I think I became sick from a different
exposure (a different patient)
Free text option: ________
c) No - I think I became sick from a different
exposure (not from a patient at my workplace)
Q9: Were you vaccinated at the time of study participation?
a) Yes, I had at least 2 doses of the COVID vaccine
c) I was not vaccinated at all at the time of
exposure
b) I had only 1 dose of COVID vaccine at the time
of the exposure
Free text option: ________
Q10: I felt safe with the PPE provided for the case:
Likert scale
response:
1
(not safe at all)
2
3
4
5
6
7
8
9
10
(very safe)
Free text option for any comments: ________
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