COVID-19 and health care worker exposure at Chris Hani Baragwanath Academic Hospital

Abstract

Background: Health care workers (HCWs) are at increased risk of coronavirus disease 2019 (COVID-19). Appropriate risk assessments and testing are essential to reduce transmission and avoid workforce depletion.

Objective: To investigate the risk of COVID-19 infection among HCWs who fulfil the person under investigation case definition or had exposure to a confirmed COVID-19 contact.

Methods: We conducted a retrospective review of HCWs who were exposed to and/or tested for COVID-19 during the first wave of the pandemic. Data collected included demographics, exposure type, risk level, and COVID-19 test result. Frequency distribution tables, bivariate analyses, univariate and multivariate analyses were conducted.

Results: Among the 1111 HCWs reviewed, 643 were tested with 35.6% positive results. PUI's accounted for 62.4% of positive cases. Symptomatic HCWs with no known contact were at a greater risk of infection than those with a patient exposure (p═0.001). The risk of testing positive was higher after a patient exposure (p═0.000) compared to a co-worker contact. Patient-facing designations had a higher risk of SARS-CoV-2 infection than non-clinical designations (p═0.013). The exception to this was security personnel who were 28 times more likely to test positive than any other designation (p═0.000).

Conclusion: There is a higher positivity rate among HCWs than the general population. The presence of symptoms warrants testing. Nosocomial transmission was derived from patients more than co-worker contacts. Precautions in the workplace need to be reinforced to protect the health and safety of HCWs during this pandemic. These findings should assist with preparedness for future pandemics.

Main article text

Introduction

Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The World Health Organization (WHO) declared the COVID-19 outbreak as a global public health emergency on 30 January 2020.(1) South Africa's first case was reported on 5 March 2020 and as of 18th September 2022, there were 4 014 442 positive cases and 102 146 deaths reported in South Africa.(2)

Healthcare workers (HCW) are at an increased risk of acquiring SARS-CoV-2 infection compared to the general population. International data has shown the estimated prevalence of SARS-CoV-2 in HCWs to be 11%.(3) In the UK and the USA, HCWs had up to a 12 fold increased risk of COVID-19 infection compared to the general population (4) and in Scotland, patient-facing HCWs were at a threefold increased risk of hospital admission from COVID-19.(5) The National Institute of Communicable Diseases (NICD) hospital surveillance survey from January 2021, reported that 3.5% of hospital admissions in South Africa were HCWs and 11.2% of them died.(6) It is critical to implement precautions and procedures in the workplace to protect the health and safety of HCWs during this pandemic.

Furthermore, nosocomial transmission of COVID-19 is a major concern as an amplifier of local transmission. Reports from different countries worldwide, including China,(7) the United Kingdom,(8,9) and the USA,(10) have shown a rapid spread of COVID-19 through health care facilities. In the first wave, a nosocomial outbreak of COVID-19 in Durban, South Africa highlighted these concerns where a single COVID-19 positive patient resulted in 119 confirmed COVID-19 cases, and of these cases, 80 were staff members.(11) Transmission occurs via aerosols that are inhaled or droplets that contain the virus and come into direct contact with mucous membranes.(12,13)

SARS-CoV-2 has placed unprecedented stress on health care systems worldwide. Chris Hani Baragwanath Academic Hospital (CHBAH) is the third-largest hospital in the world with approximately three thousand two hundred beds (14) and an average nurse to patient ratio of 3:31.(15) Before COVID-19, staff shortages were already a challenge and with quarantine periods and HCWs absent due to illness, ensuring adequate staffing was a major obstacle. The staffing crisis necessitated doctors and nurses from all departments such as Dermatology, Surgery, and Orthopaedics to curtail their usual duties and assist caring for SARS-CoV-2 infected patients and staff. Staff across CHBAH were required to comply with the hospital's Personal Protective Equipment (PPE) policy: (i) cloth masks for all non-clinical staff, (ii) face shield, medical mask, gown and gloves for all clinical staff, (iii) addition of N95 mask for staff performing aerosol-generating procedures.

While underuse of appropriate risk assessments and testing will result in rapid spread amongst HCWs and patients, overzealous quarantine or under-testing of exposed HCWs may result in unnecessary and unaffordable depletion of an already strained workforce.(16) In order to optimise health care services and protect HCWs during this pandemic, clear guidelines are required to determine if/when an exposed or symptomatic HCWs should be tested and/or self-isolate or continue to work. The Centres for Disease Control and Prevention (CDC) (17) and WHO (18) have published guidelines for the risk assessment and management of exposed and symptomatic HCWs. Based on these guidelines, the South African Department of Health (DOH) has issued guidelines relevant to the South African setting.(19) A questionnaire entitled “risk assessment questionnaire” (RAQ) was used by the CHBAH Occupational Health and Safety (OHS) department to collect relevant information in order to categorise HCWs into high-risk exposure (HRE), low-risk exposure (LRE), or person under investigation (PUI) groups and thereby direct management according to the aforementioned guidelines.

There is emerging data internationally evaluating risk assessment and testing procedures for HCWs,(20) however, local data is lacking. We undertook to assess the risk of COVID-19 among HCWs at CHBAH who fulfil the COVID-19 PUI case definition or had exposure to a confirmed COVID-19 contact.

Methods

Study sampling and study population

This is a retrospective review of the RAQs of HCWs that were exposed to and/or tested for COVID-19 by the CHBAH OHS department. RAQs over two months, from 1^st May 2020 to 1^st July 2020 were reviewed. This period was during the first wave of the COVID-19 pandemic and contained an adequate sample size of ═ 1000 RAQs.

The study population included asymptomatic HCWs exposed to a confirmed positive case and symptomatic HCWs who met the criteria of the PUI definition.

Risk assessment of HCWs

A HRE was defined as exposure within one meter to a confirmed COVID-19 case that lasts for more than fifteen minutes without appropriate PPE or failure of PPE and/or direct contact with respiratory secretions.(19) A LRE was defined as an exposure more than one meter away from a COVID-19 confirmed case OR for less than fifteen minutes OR within one meter but wearing appropriate PPE.(19) A PUI was defined as a person with acute respiratory illness with sudden onset (less than or equal to fourteen days) of at least one of the following: a cough, sore throat, shortness of breath, or anosmia/dysgeusia with or without other symptoms.(21) HCWs were managed as per the NICD and South African DOH guidelines. COVID-19 polymerase chain reaction (PCR) tests were done on all PUIs, all HRE on day eight post-exposure to assess early return to work, and HCWs in the LRE group that became symptomatic. HCWs in the PUI and HRE groups were required to self-isolate while HCWs in the LRE group were able to return to work and monitor for symptoms for fourteen days post-exposure.

Inclusion criteria

All staff working at CHBAH regardless of designation (including allied staff, security, and cleaning personnel) were included as HCWs. Staff not directly employed by CHBAH, such as medical students and non-­governmental organisation (NGO) staff were excluded as they were not required to report symptoms or exposure to CHBAH OHS but to their respective institutions. RAQs lacking risk category assessment were excluded.

Statistical analysis

Each patient received a study number, which was different from the identifiable hospital number. The study number was kept separately from the patient identification data set. Data was entered into an excel spreadsheet.

The following data was included: age, gender, designation, department, exposure type, risk level, and HCW COVID-19 test result (if tested). Only doctors and nurses were analysed with regard to “department” as other HCWs work in multiple areas.

Frequency distribution tables showing percentages and numbers were used to describe the categorical variables of age, gender, designation, department, and exposure type. Frequency distribution tables were also used to describe categorical variables with the test result (COVID positive and COVID negative result). Bivariate analyses were conducted using Pearson's Chi-square tests. The univariate and multivariable logistic regression procedure was used to determine the factors associated with positivity. Stata Inc® software version 16 was used and a p-value of less than 0.05 was considered significant. This study was approved by the Human Research Ethics Committee (Medical) of the University of the Witwatersrand.

Results

Demographic data

The sociodemographic characteristics of the 1111 HCWs are presented in Table 1. There was a female predominance (81.4%) and most of the HCWs were in the 30–39 age category (38.6%). The HCWs comprised mostly of nurses (48.5%) and doctors (27.0%). Most HCWs were from Internal Medicine (33.4%) and Obstetrics & Gynaecology (25.4%), followed by Surgery (18.9%) and Paediatrics (12.7%). Reported occupational exposures accounted for 88.8% of exposures, with 49.2% due to co-worker exposure and 39.6% due to patient exposure. Only 1.4% of HCW exposure was due to community exposure (family & travel) and 9.8% of HCWs had no known exposure. More than half of the HCWs (57.9%) met the criteria for testing for SARS-CoV-2.

Table 1:

Sociodemographic characteristics of HCWs

Variables	Frequency (n) n═1111	Percent (%)
Age (in years)
<30	220	19.8
30–39	429	38.6
40–49	271	24.4
50–60	165	14.8
>60	26	2.3
Gender
Female	904	81.4
Male	207	18.6
Designation
Allied	101	9.1
Cleaner	36	3.2
Doctor	300	27.0
Nurse	539	48.5
Pharmacist	1	0.09
Radiographer	12	1.1
Support & Logistics	102	9.2
Security	20	1.8
Department	n═839*
Anaesthesiology	10	1.2
Emergency	35	4.2
Internal Medicine	280	33.4
Obstetrics & Gynaecology	213	25.4
Paediatrics	107	12.7
Psychiatry	25	3.0
Radiology	10	1.2
Surgery	159	18.9
Exposure type
Co-worker	547	49.2
Family	14	1.3
No known contact	109	9.8
Patient	440	39.6
Travel	1	0.1
Tested for SARS-CoV-2
Yes	643	57.9
No	468	42.1

*Only Doctors and Nurses included in Department

All data expressed as frequencies and percentages

Risk level and COVID-19 test results

Only 19.0% met the criteria for HRE, whilst 51.1% for LRE and 29.9% fulfilled the definition of a PUI. The positivity rate in the PUI and HRE groups was 43.1% and 25.6% respectively. In the LRE group, 83.1% of HCWs were not tested as they did not fulfil criteria for testing. However, 17.0% of LRE HCWs became symptomatic within 14 days post-exposure and were tested. Of the HCWs in the LRE group that were tested, 32.0% were positive (Table 2). A significant association between test result and risk level was noted (p═0.001).

Table 2:

SARS-CoV-2 result and risk level

Variables	PUI n═332 n (%)	HRE n═211 n (%)	LRE n═100ϯ n (%)	Total n═643 n (%)	p-value
SARS-CoV-2 result
Positive	143 (43.1)	54 (25.6)	32 (32.0)	229 (35.6)	0.0001
Negative	189 (56.9)	157 (74.4)	68 (68.0)	414 (64.4)

*PUI═person under investigation HRE═high risk exposure LRE═low risk exposure

ϯBecame symptomatic and therefore tested

Factors associated with increased risk of COVID-19 infection

A total of 643 participants were tested with 35.6% positive results (Table 3). More than half the HCWs were nurses (53.7%) followed by doctors (24.9%). Staff in the departments of Internal Medicine (38.3%) and Obstetrics & Gynaecology (17.2%) accounted for most of the positive cases followed by staff in the departments of Paediatrics (14.4%) and Surgery (13.9%). Patient contact was reported in 42.4%, followed by co-worker contact (28.4%), no known contact (25.3%), and a family contact (3.9%). The PUI group accounted for 62.4% of the positive cases followed by 23.6% in the HRE group and 14.0% were from the LRE group that became symptomatic and were therefore tested. A significant association was noted between age (p═0.0201), department (p═0.0001), designation (p═0.0001), exposure type (p═0.0001), risk level (p<0.0001) and a positive test result. There was no significant association between gender (p═0.9621) and test result.

Table 3:

Distribution of HCW demographics and COVID-19 test result

Variables	COVID-19 Positive n═229 n (%)	COVID-19 Negative n═414 n (%)	p-value
Age (in years)
<30	26 (11.4)	91 (22.0)	0.0201
30–39	91 (39.7)	152 (36.7)
40–49	65 (28.4)	99 (23.9)
50–60	40 (17.5)	59 (14.3)
>60	7 (3.1)	13 (2.0)
Gender
Female	184 (80.3)	332 (80.2)	0.9621
Male	45 (19.7)	82 (19.8)
Designation
Allied	16 (7.0)	40 (9.7)	0.0001
Cleaner	6 (2.6)	18 (4.3)
Doctor	57 (24.9)	95 (22.9)
Nurse	123 (53.7)	213 (51.4)
Pharmacist	0 (0)	1 (0.2)
Radiographer	1 (0.4)	0 (0)
Support & Logistics	12 (5.2)	45 (10.9)
Security	14 (6.1)	2 (0.5)
Department
Anaesthesiology	10 (5.6)	0 (0)	0.0001
Emergency	6 (3.3)	14 (4.5)
Internal Medicine	69 (38.3)	122 (39.6)
Obstetrics & Gynaecology	31 (17.2)	89 (28.9)
Paediatrics	26 (14.4)	28 (9.1)
Psychiatry	12 (6.7)	10 (3.2)
Radiology	1 (0.6)	0 (0)
Surgery	25 (13.9)	45 (14.6)
Exposure type
Co-worker	65 (28.4)	226 (54.6)	<0.0001
Family	9 (3.9)	5 (1.2)
No known contact	58 (25.3)	32 (7.7)
Patient	97 (42.4)	151 (36.5)
Travel	0 (0)	0 (0)
Risk level
PUI	143 (62.4)	189 (45.7)	0.0001
HRE	54 (23.6)	157 (37.9)
LRE	32 (14.0)	68 (16.4)

*Only Doctors and Nurses included in Department

ϯPUI═person under investigation HRE═high risk exposure LRE═low risk exposure

In a univariate analysis (Table 4) the age groups from 30 to 60 years were at a higher risk of COVID-19 infection, with the highest risk in the 50–60 year age group (p═0.004). Security personnel were more likely to test positive than nurses (p═0.001) while support and logistics staff were less likely to test positive than nurses (p═0.025). The wide confidence interval seen in the security group can be explained by the small sample size. There was no significant difference between nurses’ and doctors’ positivity rates (p═0.850). HCWs in Obstetrics and Gynaecology were less likely to test positive than HCWs in Paediatrics (p═0.004). Symptomatic HCWs who reported no known exposure to COVID-19 were more likely to have a positive COVID-19 test result than those who reported an occupational exposure to a COVID-19 positive patient contact (p═0.000). In terms of occupational exposure, the risk of testing positive for COVID-19 was less after exposure to a co-worker contact as compared to a patient contact (p═0.000). PUIs were more likely to test COVID-19 positive than LREs that became symptomatic (p═0.049).

Table 4:

Univariate analysis of sociodemographic characteristics and COVID-19 test result

	COVID-19 Positive
Variable	AOR	95%CI	p-value
Age (years)
<30	1
30–39	2.09	1.26–3.48	0.004
40–49	2.29	1.35–3.92	0.002
50–60	2.37	1.31–4.29	0.004
>60	1.88	0.68–5.21	0.222
Designation
Nurse	1
Doctor	1.03	0.69–1.54	0.850
Allied	0.69	0.37–1.28	0.246
Support & Logistics	0.46	0.23–0.90	0.025
Cleaner	0.57	0.22–1.49	0.257
Security	12.12	2.7–54.2	0.001
Department
Paediatrics	1
Internal Medicine	0.61	0.33–1.12	0.111
Surgery	0.59	0.29–1.23	0.164
Obstetrics & Gynaecology	0.37	0.19–0.73	0.004
Emergency	0.46	0.15–1.37	0.166
Psychiatry	1.29	0.47–3.49	0.613
Exposure type
Patient	1
Co-worker	0.44	0.30–0.65	0.000
No known exposure	2.82	1.70–4.65	0.000
Family	2.80	0.91–8.61	0.072
Risk level
LRE	1
HRE	0.73	0.43–1.23	0.239
PUI	1.61	1.00–2.58	0.049

*Only Doctors and Nurses included in Department

ϯPUI═person under investigation HRE═high risk exposure LRE═low risk exposure

In light of other factors, the adjusted multivariate analysis (Table 5) showed a lower odds of COVID-19 infection in the HRE group as compared to the LRE that became symptomatic (AOR═0.54; 95%CI:0.30–0.99; p═0.049). The odds of COVID-19 infection was higher in age groups 30–39 years (AOR═2.94; 95%CI:1.61–5.35; p═0.000), 40–49 years (AOR═2.75; 95%CI:1.46–5.18; p═0.002) and 50–60 years (AOR═2.161; 95%CI:1.31–5.23; p═0.007) as compared to < 30 years. Symptomatic HCWs with no known exposure were at a greater odds of infection than those with an occupational patient exposure (AOR═2.58; 95%CI:1.45–4.60; p═0.001) and an increased risk of infection was seen with a family exposure as compared to occupational exposure (AOR═3.54; 95%CI:0.97–12.88; p═0.055). Staff working in security were more likely to test COVID-19 positive than nurses (AOR═28.27; 95%CI:5.67–140.93; p═0.000) whilst Support and logistics were less likely (AOR═0.36; 95%CI:0.16–0.80; P═0.013).

Table 5:

Multivariate analysis of sociodemographic characteristics and COVID-19 test result

	COVID-19 Positive
Variable	AOR	95%CI	p-value
Risk level
LRE	1
HRE	0.54	0.30–0.99	0.049
PUI	1.43	0.84–2.47	0.186
Age
<30	1
30–39	2.94	1.61–5.35	0.000
40–49	2.75	1.46–5.18	0.002
50–60	2.61	1.31–5.23	0.007
Exposure type
Patient	1
Co-worker	0.36	0.23–0.54	0.000
No known contact	2.58	1.45–4.60	0.001
Family	3.54	0.97–12.88	0.055
Department
Paediatrics	1
Internal Medicine	0.57	0.43–0.97	0.037
Surgery	0.53	0.27–1.05	0.067
Obstetrics & Gynaecology	0.58	0.31–1.07	0.081
Designation
Nurse	1
Security	28.27	5.67–140.93	0.000
Support & Logistics	0.36	0.16–0.80	0.013
Allied	0.47	0.19–1.12	0.088

*PUI═person under investigation HRE═high risk exposure LRE═low risk exposure

Discussion

The WHO declared the COVID-19 outbreak as a global public health emergency on 30 January 2020.(1) HCWs are the frontline response to the COVID-19 pandemic and their occupational health and safety is central to the fight against the outbreak and maintenance of the health workforce. There is increasing evidence showing that HCWs are at a greater risk of SARS-CoV-2 infection than the general population.(3) Our findings show a higher positivity rate of SARS-CoV-2 infection in HCWs (35.6%) compared with the NICD data from the general population in South Africa reported at this time showing a positivity rate of up to 7.5% (22) although different testing strategies may contribute to this discrepancy.

The majority of HCWs were female (82.7%) however, there was no significant association between gender and COVID-19 result. This concurs with a seroprevalence study in healthy South African blood donors which showed no gender predilection (23) and in the UK and USA where risk estimates of COVID-19 were similar between male and female HCWs.(4) Our results likely reflect the demographics of HCWs employed at CHBAH as well as the superior healthcare-seeking behaviour seen in females.(24)

We found that HCWs between 50 and 60 years were the most likely age group to test COVID-19 positive. As age is a risk factor for severe disease,(25) HCWs in older age groups should be particularly vigilant with infection prevention control (IPC) protocols and correct PPE. Our findings are in contrast to HCWs in Switzerland where being older than 50 years was associated with a lower seroprevalence. This difference may be explained by age-related declines in humoral immunity affecting the seropositivity versus PCR tests in our study which will not be affected by this.(20)

Health care worker designation is a significant predictor of COVID-19 positivity in our study as well as other studies in Denmark,(26) Switzerland,(20) Scotland,(5) Ghana,(27) and Cape Town, South Africa.(28) These studies all show that patient-facing designations such as nurses have a higher risk of SARS-CoV-2 infection than non-­patient facing, non-clinical designations such as support & logistics. Furthermore, HCW COVID-19 infections were more likely as a result of a patient contact than a co-worker contact. These findings suggest nosocomial transmission, particularly from patients, to be the major source of COVID-19 infections in HCWs.

Of particular significance in our study, however, is that security personnel were almost thirty times more likely to test COVID-19 positive than any other designation. Security personnel wear standard PPE (cloth or surgical masks only) compared to clinical staff that were required to wear a face shield and a surgical or N95 mask; are required to check bags and vehicles of all people entering and exiting the hospital; and are in close proximity to those on their shift, HCWs, and patients. Moreover, security personnel may be less aware of the risks of severe COVID-19 infection and this may influence their stringency to follow personal protective measures. These factors likely contributed to this high positivity rate and highlight the necessity of adequate PPE, IPC protocols, and training for all HCWs regardless of designation to reduce transmission.

HCWs in Internal Medicine showed the highest rates of COVID-19 positive results, however, a multivariate analysis showed that HCWs in Paediatrics had the highest risk of COVID-19 infection. Initial studies have shown that children are less likely to be infected by and transmit SARS-CoV-2 (29) and this may have led to complacency in protective measures in paediatric staff. The nature of the close patient and parent contact in this department and the paucity of symptoms often shown in paediatric populations may further contribute to increase in transmission risk. There is growing data to suggest that Paediatric HCWs are at a greater risk of COVID-19 infection than initially presumed.(30,31)

One of the strongest predictors of SARS-CoV-2 infection in HCWs is “symptoms”. The risk of COVID-19 was higher in HCWs who were symptomatic but had no known exposure than HCWs exposed to a patient contact. Almost two-thirds of the COVID-19 positive HCWs in our study were in the PUI risk level and symptoms were a stronger predictor of SARS-CoV-2 infection than a positive HRE history. These findings are supported by a meta-analysis showing that symptoms were significantly associated with SARS-CoV-2 infection in HCWs.(3)

With the rollout of vaccinations in South Africa, HCWs may feel influenced to be less stringent with PPE when treating patients with COVID-19. However, COVID-19 infection is still possible post-vaccination. In Israel, 22 of 4081 (0.54%) HCWs developed COVID-19 within 10 days post-vaccination.(32) Our study highlights the importance of continuously monitoring for symptoms, even post-vaccination.

There are some limitations to this study. This study was a retrospective review and testing was done only on HCWs who fulfilled criteria based on the South African DOH guidelines. Therefore the true prevalence of asymptomatic infection in LREs was not able to be determined. This testing strategy may have been influenced by resource constraints at the time and limited access to testing. The HCW screening algorithm relied on self-reporting and HCWs might have had a recall bias. A small sample size was noted in certain designations such as security personnel and we recommend future studies to look further into these subgroups. There may be selection bias in this study as it was performed at the start of the pandemic and therefore may not be representative of infection rates later on in the pandemic.

Conclusion

Our results show a higher positivity rate of HCWs compared to the general population. Nosocomial transmission was derived from patients more than co-workers and therefore strict PPE and IPC protocols should be adhered to. Symptoms were one of the greatest predictors of infection irrespective of exposure history. Our findings support the amended guidelines where the presence of symptoms is the most important indicator for testing and isolation. Evidence-based HCW screening protocols are required to ensure HCW safety and at the same time adequate staffing. The findings of this study are important in ensuring preparedness of HCWs for future pandemics.

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