Supplement article - Research | Volume 5 (1): 4. 22 Feb 2022 | 10.11604/JIEPH.supp.2022.5.1.1198

Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

James Sylvester Squire, Dora Dadzie, Kofi Mensah Nyarko, Anthony Danso-Appiah, Basil Benduri Kaburi, Charles Lwanga Noora, Mohamed Alex Vandi, Donne Kofi Ameme, Ernest Kenu, Samuel Oko Sackey

Corresponding author: James Sylvester Squire, Directorate of Health Security and Emergencies, MOHS, Cockrill, Wilkinson road, Freetown, Sierra Leone

Received: 12 Apr 2021 - Accepted: 14 Dec 2021 - Published: 22 Feb 2022

Domain: Epidemiology,Infectious diseases epidemiology,Public health

Keywords: Risk factors, COVID-19, SARS-CoV-2, Healthcare workers, Hospital, Sierra Leone

This articles is published as part of the supplement Preparedness and response to COVID-19 in Africa (Volume 2), commissioned by AFRICAN FIELD EPIDEMIOLOGY NETWORK (AFENET).

©James Sylvester Squire et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Cite this article: James Sylvester Squire et al. Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020. Journal of Interventional Epidemiology and Public Health. 2022;5(1):4. [doi: 10.11604/JIEPH.supp.2022.5.1.1198]

Available online at: https://www.afenet-journal.net/content/series/5/1/4/full

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Research

Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

James Sylvester Squire1,2,&, Dora Dadzie3, Kofi Mensah Nyarko4, Anthony Danso-Appiah5, Basil Benduri Kaburi1, Charles Lwanga Noora1, Mohamed Alex Vandi2, Donne Kofi Ameme1, Ernest Kenu1, Samuel Oko Sackey1

 

1Ghana Field Epidemiology and Laboratory Training Program, University of Ghana, Accra, Ghana, 2Directorate of Health Security & Emergencies, MOHS, Sierra Leone, 3Cape Coast Teaching Hospital, Cape Coast, Ghana, 4African Field Epidemiology Network (AFENET), 5School of Public Health, University of Ghana, Accra, Ghana

 

 

&Corresponding author
James Sylvester Squire, Directorate of Health Security and Emergencies, MOHS, Cockrill, Wilkinson road, Freetown, Sierra Leone. jmssquire@yahoo.com/ jamessquire471@gmail.com

 

 

Abstract

Introduction: Healthcare workers (HCWs) are at increased risk of COVID-19 infection due to their role in caring for patients. Despite reports of HCW infections in Sierra Leone, little information exists on the extent and risk factors for infection in healthcare settings. We assessed the extent and risk factors for COVID-19 infection among HCWs exposed to COVID-19 patients at three regional hospitals in Sierra Leone.

 

Methods: We conducted a case-ascertained prospective study in Bo, Kenema, and Port Loko Regional Hospitals from May to July 2020. We recruited and followed HCWs who were exposed to confirmed COVID-19 patients. A semi-structured questionnaire was used to collect data on demographics, clinical presentation, exposures and contact information. Infection status was determined by laboratory detection of SARS-CoV-2 RNA by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) on nasopharyngeal swab samples. We assessed risk factors using Poisson regression with robust error variance.

 

Results: Out of 152 participants, 58.6% (89/152) were from Bo Government Hospital, 20.4% (31/152) from Port Loko Government Hospital, and 21.0% (32/152) from Kenema Government Hospital. The median age was 34.0 years (range: 20 – 63 years). About 74.3% (113/152) were females. Overall, the secondary infection rate (SIR) was 28.9% (44/152). SIR was highest among cleaners (55.6% [10/18]). About 68.2% (30/44) of infected HCWs were asymptomatic. Among symptomatic cases, the most common symptoms were headache 27.3% (12/44), fever 18.2% (8/44), and cough 15.9% (7/44). Contact with surfaces around patient (RR=2.3, 95%CI: 1.41–3.61, p=0.001), exposure at the triage/isolation or outpatient unit (RR=2.4, 95% CI: 1.51 – 3.67, p<0.001) and cleaning of patient room (RR=2.2, 95%CI: 1.36–3.64, p=0.001) were associated with increased risk of COVID-19 infection. Good hand hygiene practice (RR=0.4, 95%CI: 0.23–0.56, p<0.001) was associated with a decreased risk of infection.

 

Conclusion: The infection rate for COVID-19 among HCWs was high. Contact with patient's environment, cleaning of patient room, and exposure at the triage or outpatient units were risk factors for infection. We emphasized the need for strict adherence to infection control measures by HCWs. Keywords: Risk factors, COVID-19, SARS-CoV-2, Healthcare workers, Hospital, Sierra Leone

 

 

Introduction    Down

The Coronavirus Disease 2019 (COVID-1) pandemic, caused by severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), was first detected in Wuhan, China in December 2019 [1]. Since its emergence, COVID-19 has spread globally posing serious public health and security threats. As at May 4, 2020, there had been over three million cases of COVID-19 and 239,604 deaths reported worldwide, with the WHO African region accounting for 0.9% (30,536 cases) and 0.5% (1,085 deaths) of the global cases and deaths [2]. In Sierra Leone, the first case of COVID-19 was reported on March 30, 2020. By May 4, 2020, the country had recorded 178 confirmed COVID-19 cases and nine deaths in eight out of sixteen districts [3].

 

During the ongoing COVID-19 pandemic, healthcare workers (HCWs) continue to play a critical role at the frontline of health service delivery, providing both COVID-19 and non-COVID-19 essential services. As a result, they are at increased risk of becoming infected with SARS-CoV-2. This is particularly the situation in the case of novel disease outbreaks when transmission dynamics are yet to be fully understood. Globally an estimated 22,073 confirmed cases of COVID-19 have been reported among HCWs as of April 8, 2020 [4]. In China, a total of 1,716 HCWs were infected by February 11th, 2020 [5]. In the WHO African Region, an estimated 945 cases were reported among HCWs in 28 countries by May 5, 2020 [6]. COVID-19 infection rates among HCWs vary widely across settings and testing methods used. In the Netherlands and the United Kingdom, infection rates of 6.0%, 11.0% and 18.0% were reported among symptomatic HCWs by rRT-PCR method [7-9]. A retrospective cohort study conducted in Wuhan, China among HCWs in a designated hospital reported an infection rate of 38.9% by rRT-PCR method [10]. A seroprevalence study conducted in Malawi among 500 asymptomatic HCWs reported an infection rate of 12.3% [11]. Recent studies conducted mainly in China and Europe have highlighted some important risk factors for COVID-19 infection among HCWs in healthcare settings [10,12-17]. These factors include, age, job category, pre-existing medical conditions, work unit, lack of training in infection prevention and control (IPC), improper use of personal protective equipment (PPE), non-compliance to hand hygiene measures, unprotected contact with COVID-19 patient, and exposure to certain aerosol-generating procedures.

 

In Sierra Leone, the first case of HCW infection was reported on April 2, 2020, in a tertiary referral hospital in Freetown [18]. By May 4, 2020, a total of 29 HCWs had been infected, being among the first known cases of possible nosocomial spread of COVID-19 in healthcare settings. Despite reports of HCW infections in Sierra Leone, information on the extent and risk factors for infection has not been documented. We therefore determined the secondary infection rate and risk factors for COVID-19 infection among HCWs exposed to COVID-19 patients in three regional hospitals in Sierra Leone as a basis for targeting interventions to reduce transmission of COVID-19 within healthcare settings.

 

 

Methods Up    Down

Study Design and Settings

 

We conducted a case-ascertained prospective study among HCWs exposed to COVID-19 patients at three regional hospitals in Bo, Port Loko, and Kenema districts in Sierra Leone. The study was conducted from May 6 to July 4, 2020. The three hospitals are the main public referral hospitals in these districts. Bo Government Hospital (BGH) and Kenema Government Hospital (KGH) have 300 beds each, whilst the Port Loko Government Hospital (PLGH) has 150 beds, with a total staff of over 2,000 persons shared among the three hospitals. All three hospitals have triage stations for screening of patients and isolation facilities for suspected COVID-19 patients. The index case of COVID-19 at the BGH was reported on May 3, 2020. The case-patient, a 59-year-old male, was admitted on April 29, 2020 for a non-COVID-19 related condition. The case-patient was transferred after two days of hospitalization to the Connaught Teaching Hospital Complex in Freetown where the diagnosis was made. The index case at the PLGH was confirmed on May 9, 2020 in a 44-year-old male. The case-patient made two outpatient visits to the hospital and on his second visit on May 4, 2020 he was admitted for two days for a COVID-19 unrelated condition. The KGH reported its index case on May 16, 2020 after being hospitalized for six days. The case-patient, a 20-year-old male was admitted on May 10, 2020 and was being treated for malaria and hypertension prior to confirmation of COVID-19. At the time of admission of index cases at the respective hospitals, COVID-19 was not suspected as case-patients reported no travel or exposure-related history. Thus, attending HCWs observed little or no standard precautions during care for these cases.

 

Study population, recruitment and follow-up

 

The study population included HCWs who were exposed to the index cases at the respective hospitals and from whom nasopharyngeal swab samples were collected (Figure 1). All HCWs with a confirmed COVID-19 case among their households or close contacts and those who travelled out of the study districts within two weeks prior to confirmation of the index cases were excluded. HCWs were defined as all staff (clinical and non-clinical) involved in the provision of care for COVID-19 infected patients at the three hospitals, including those who have been present in the same area as the patient, as well as those who may not have provided direct care to the patient, but who have had contact with the patient´s body fluids, potentially contaminated items or environmental surfaces.

 

To recruit study participants in the respective hospitals, investigators reviewed duty rosters and medical files of the index cases and held meetings with individual units the patients visited or were admitted to. Identification and recruitment of HCWs were done in consultation with the hospital administration and those identified were quarantined and followed up as per the Government protocol on COVID-19 quarantine and contact tracing [19]. We enrolled participants at different times during the study depending on when the index cases were identified and the date the HCWs started quarantine. Thus, the follow-up times varied depending on the enrolment date and the time spent in COVID-19 treatment facilities for those that tested positive. In BGH, HCWs were enrolled and followed up from May 6 through July 4, 2020, while in Port Loko and Kenema Government hospitals from May 11 to June 22, 2020 and from May 17 to June 24, 2020 respectively. Enrolled HCWs were followed daily for COVID-19 symptoms for the first 14 days of their last exposure to the case-patients. Those that became positive were admitted and followed up at the treatment centre to document the range of clinical presentations and outcome. Follow up of those tested negative ended upon receipt of second negative result at day 14 of last exposure.

 

Our sample was 181 participants: 110 (60.8%) were recruited at BGH; 36 (19.9%) were recruited at PLGH; and 35 (19.3%) were recruited at KGH. We excluded 14 HCWs in whom nasopharyngeal swab samples were not collected and 15 HCWs who did not consent. The final sample thus comprised 152 (84% of eligible) participants Figure 1.

 

Data collection

 

Baseline information at enrolment was collected for each participant after written consent was obtained. A semi-structured interviewer-administered questionnaire adapted from the WHO protocol for “assessment of potential risk factors for COVID-19 infection among health care workers in a health care setting” [20] was used to collect information. In addition to sociodemographic data (age, sex, nationality, work location, job category, and smoking status), we collected information on pre-existing medical conditions and respiratory and general symptoms. Information about IPC training was collected. Detailed contacts and exposure information were also collected to include exposure location, close contact (within 1 meter) with index patients, number and duration of contact with index patients, contact with patient materials, contact with surfaces around patient and exposure to aerosol-generating procedures (AGP) or body fluids. We also collected data on patient care activities while in contact with the patient, and compliance with recommendations for personal protection such as, wearing of mask (surgical/N95), gloves, face shields or goggles, gown and consistent hand hygiene practice with alcohol-based hand rub (ABHR) or soap and water after each patient contacts.

 

Each HCW enrolled was given a symptom diary and asked to record daily the presence or absence of respiratory or other general signs and symptoms for the period in quarantine or at the treatment centre. Follow-up through phone calls was made at 5:00 pm daily by trained research assistants to ensure compliance and to document on a separate follow-up sheet the record on the symptom diary. All questionnaires were administered in English and all personnel involved in the study were trained on standard IPC procedures specific to COVID-19 and based on national guidelines [21].

 

Laboratory methods

 

Two nasopharyngeal swab samples were collected from each participant irrespective of symptoms as per the MOHS guideline [19]. The first sample was collected at baseline on enrolment and the second on day 14 of follow-up. For HCW that reported symptoms during follow-up, an immediate nasopharyngeal swab was collected. Samples collected were stored in viral transport media at 2-8oC and transported the same day in triple packaging to the testing facilities for COVID-19. Samples from Bo and Kenema were sent to the Viral Haemorrhagic Fever Reference Laboratory in Kenema district and samples from Port Loko were sent to the Sierra Leone-China Friendship Biological Safety Laboratory (Jui P3 laboratory) in Western area. Laboratory testing for SARS-CoV-2 was performed by trained laboratory scientist and virologists. Laboratory confirmation of COVID-19 was based on the detection of unique sequences of virus RNA by rRT-PCR method as described in the MOHS laboratory guideline for COVID-19 [22]. Laboratory test results were recorded on a laboratory form for each HCW. HCWs with positive test results at baseline or during follow-up were transferred to a designated COVID-19 treatment facility for management of symptoms and outcome documented.

 

Outcome measure

 

The outcome was confirmed COVID-19 infection. This was defined as a HCW contact of a positive COVID-19 case with a positive laboratory result for SARS-CoV-2 by real-time RT-PCR test on nasopharyngeal swab specimen collected at baseline and or during follow-up irrespective of symptoms. The median days from last exposure to first sample collections was 7.0 days (range: 4 - 11 days). Therefore, HCWs who tested positive at baseline were presumed to have been exposed to the index cases, thus were included in the analysis.

 

Data analysis

 

Data were entered into SPSS, cleaned, and all variables were coded. Continuous variables like age were categorised for analysis. We analysed data using Stata IC version 15.1 (StataCorp, Texas, USA) software. Descriptive statistics were used to summarize the demographic and exposure characteristics of the study population. Median and range were used to describe continuous variables and categorical variables were described using frequencies and proportions. To assess the extent of infection, we estimated the overall secondary infection rate (SIR) (and its 95% confidence interval) as the proportion of all enrolled HCWs exposed to the case-patients who subsequently became infected with COVID-19. Two sample test of proportion was used to compare SIR for COVID-19 among age group, sex, pre-existing conditions, smoking status and reported close contact with index patients. Differences in proportions observed between COVID-19 positive and negative HCWs for categorical variables were compared using Pearson Chi-squared or Fisher´s exact tests of association. To determine risk factors for COVID-19 infection among HCWs, a bivariate and multivariable Poisson regression analysis with robust error variance was carried. For the construction of the multivariable model, we used a purposeful selection method described in Hosmer et al. [23]. Relative risk (RR) and 95% confidence interval (CI) were computed to assess the strength of association and level of statistical significance was set at p-value <0.05.

 

A model diagnostic was performed to assess the adequacy and fit of the final model. The goodness of fit was evaluated with the test of the deviation, which showed a very good fit (degrees of freedom=146; deviance=77.95; p-value=0.99).

 

Availability of data and materials

 

The dataset for this study can be made available upon request. The dataset is available in Excel spreadsheet (XLSX 506 kb) and in STATA file format.

 

Ethical considerations

 

We obtained ethical approval from the Sierra Leone Ethics and Scientific Review Committee. Permission was also sought from the management of the Bo, Kenema and Port Loko Government Hospitals. Written informed consent was obtained from all study participants and a unique identifier for the labelling of questionnaire and clinical specimens was assigned to each subject.

 

 

Results Up    Down

Demographic and exposure characteristics of study participants

 

Of 152 HCWs recruited into the study, 58.6% (89/152) were from the BGH, 20.4% (31/152) from the PLGH and 21.0% (32/152) from the KGH. The median age of study participants was 34.0 years (range, 20 - 63 years), with the majority, 95.4% (145/152) less than 50 years old. The majority of participants were females 74.3% (113/152); of Sierra Leonean nationality 98.7% (150/152); and did not smoke 96.1% (146/152). Most of the HCWs 45.4% (69/152) were State Enrolled Community Health Nurses (SECHN). About 77.0% (117/152) of respondents were exposed at the inpatient ward, 17.8% (27/152) at the triage/isolation or outpatient units and 5.2% (8/152) at the x-ray or laboratory unit. Only 7.2% (11/152) had pre-existing medical conditions with hypertension 3.3% (5/152) and asthma 2.0% (3/152) being the most frequent. The distributions of demographic (age, sex, job category), lifestyle (cigarette smoking), pre-existing condition and HCW IPC training status were comparable between HCWs diagnosed with COVID-19 and those without COVID-19 Table 1.

 

Most of the HCWs 58.6% (89/152) had close contact (within 1 meter) with index patients, 40.1% (61/152) had prolonged (more than 15 minutes) face-to-face contact with patient.

 

The median age of COVID-19 positive HCWs was 34.0 years (range, 21 -54 years) and that for COVID-19 negative HCWs was 33.5 years (range, 20 - 63 years).

 

About 57.2% (87/152) of respondents carried out at least one activity during exposure to index patients, while 42.8% (65/152) reported no direct patient care activity only stayed in the same room with the index patients Table 2. None of the HCWs reported exposure to aerosol-generating procedures.

 

Secondary infection rate (SIR) for COVID-19 among exposed hospital HCWs

 

Overall 44 out of 152 exposed HCWs tested positive for COVID-19 during the study, yielding a secondary infection rate of 28.9% (95% CI: 21.9% - 36.8%). All HCWs diagnosed with COVID-19 survived with none requiring ventilation. The SIR varied slightly by hospital with BGH, 27.0% (24/89), PLGH, 25.8% (8/31) and KGH, 37.5% (12/32) (Table 3). SIR also varied by job category with cleaners having the highest SIR (55.6% (10/18)), followed by other health staff (28.6% (10/35)), Nursing Aid (26.7% (4/15)) and SECHN (26.1% (18/69)). SIR was also highest among staff exposed at the triage or outpatient unit of the hospitals (59.3% (16/27)). There were significant differences in the SIR for COVID-19 among HCWs who had close contact with the index patients than among those who did not (z= -3.353; p-value < 0.001). Secondary infection rates did not differ by age, sex, pre-existing condition and smoking status Table 3.

 

About 68.2% (30/44) of infected HCWs reported no symptoms. Among those that reported symptoms (31.8% (14/44)), headache 27.3% (12/44), fever 18.2% (8/44) and cough 15.9% (7/44) were the common symptoms reported. Among COVID-19 positive HCWs, 93.1% (41/44) had no pre-existing medical conditions. Hypertension 4.5% (2/44) and asthma 2.3% (1/44) were the conditions reported Table 4.

 

Risk factors for COVID-19 infection among HCWs

 

In a bivariable analysis, close contact (within 1 meter) with index patient (CRR=2.8, 95%CI: 1.42-5.32), greater than two estimated individual contacts (CRR=3.5, 95%CI: 1.67-7.32), lifting or positioning patient (CRR=2.4, 95%CI 1.48-3.79), changing patient bed linens (CRR=2.2, 95%CI: 1.30-3.68), cleaning patient room (CRR=2.5, 95%CI: 1.55-4.04), exposure at the triage or outpatient unit (CRR=2.7, 95%CI: 1.68-4.24), contact with patient body fluids (CRR=2.1, 95%CI: 1.23-3.45), contact with patients materials (CRR=2.5, 95%CI: 1.56-4.08) and contact with surfaces around patient (CRR=2.9, 95%CI: 1.79-4.84) were significant risk factors for COVID-19 infection Table 5.

 

Conversely, wearing of N95 mask, gloves, face shields or gown during contact with index patient significantly decreases the risk of COVID-19 infection. HCWs who wore N95 masks during contact with index case had 70% decreased risk of COVID-19 infection than HCWs who did not wear N95 masks (CRR=0.3, 95%CI: 0.18-0.57). HCWs who reported wearing gloves (CRR=0.5, 95%CI: 0.30-0.83), or face shields (CRR=0.4, 95%CI: 0.23-0.75) or gown (CRR=0.4, 95%CI: 0.26-0.73) during contact with index patient had significantly decreased risk of COVID-19 infection than those who did not. Similarly, HCWs who performed hand hygiene with ABHR or soap and water after each contact with the index patients had 70% lower risk of COVID-19 infection than those who did not (CRR=0.3, 95%CI: 0.19-0.41). Other factors such as age, sex, job category, pre-existing medical conditions and smoking showed no significant association with testing positive for COVID-19 in the bivariate analysis (Table 5).

 

In the multivariable logistic regression analysis, contact with surfaces around the patient, exposure at the triage/isolation or outpatient unit and cleaning of patient room were significant independent risk factors for COVID-19 infection among hospital HCWs (Table 5). The risk of COVID-19 infection among HCWs who had contact with surfaces around the patient was twice higher than those who did not (ARR=2.3, 95%CI: 1.41-3.61). The risk of infection increased more than two folds among HCWs who got exposed at the triage/isolation or outpatient unit of the hospitals compared to HCWs who got exposed at the inpatient wards of the hospitals (ARR=2.4, 95% CI: 1.51 - 3.67). HCWs who cleaned patient rooms had a two-fold increased risk of infection than those that did not clean the patient rooms (ARR=2.2, 95%CI: 1.36-3.64). There was a significantly decreased risk of COVID-19 infection among HCWs that performed hand hygiene with ABHR or soap and water (ARR=0.4, 95%CI: 0.23-0.56) compared to those that did not (Table 5).

 

 

Discussion Up    Down

This study found an overall secondary infection rate of 28.9% for COVID-19 in the study population. This was substantially higher than the infection rates of 6.0% and 11.0% reported in previous studies from the Netherlands and 18.0% in United Kingdom [7-9]. These studies however conducted only one rRT-PCR test on symptomatic HCWs with fever or mild respiratory symptoms. The overall infection rate in this study was lower than what was reported in a study conducted in China that reported an infection rate of 38.9% [10]. While the current study excluded HCWs with close family members with COVID-19 infection, the authors in the study conducted in China included HCWs that got exposed to family members with COVID-19. This could have accounted for the much higher infection rate obtained in the study. A universal screening conducted among HCWs in a maternity hospital in London from 7th March through 16th April, 2020 reported an infection rate of 18.0% [24]. A report from a seroprevalence study conducted among 500 asymptomatic HCWs (331 clinical and 169 non-clinical staff) from Blantyre City, Malawi indicated an overall infection rate of 12.3% after adjusting for test sensitivity and specificity [11]. The present study observed SIR to be highest among cleaners (55.6%), followed by nursing aids (26.7%) and SECHNs (26.1%). This was contrary to findings from other studies that reported high infection rates among clinical staff than non-clinical staff [25-27]. This study hypothesized that cleaners most likely were exposed to contaminated surfaces or patient materials during cleaning of index patient rooms and or changing patient bed linens.

 

The study also observed high infection rate among HCWs exposed at triage/isolation or outpatient units of the hospitals. COVID-19 infection rates have been shown to vary between clinical departments [10,27-30]. The high infection rates reported among HCWs in this study is alarming, thus testifying to the lack of knowledge of the virus and the need for improvement in infection control practices.

 

In this study, a large proportion (68.2%) of HCWs with COVID-19 reported no symptoms. For symptomatic HCWs, headache, fever and cough were the most frequent symptoms reported; findings consistent with other studies [7,31-34]. The high proportion of infected asymptomatic HCWs observed in this study has important implications for infection prevention and control precautions in healthcare facilities. Although the role of asymptomatic transmission of SARS-CoV-2 has not been fully established [35], preliminary evidence suggests people with asymptomatic infections can spread the virus [35-40]. HCWs with unrecognized COVID-19 infection may serve as a major risk group for nosocomial transmission and amplification events within healthcare facilities. Thus, control of SARS-CoV-2 transmission in a healthcare setting could depend on maintaining a low threshold for suspicion of COVID-19 infection among exposed HCWs.

 

Nosocomial transmission of respiratory diseases including COVID-19 is a common occurrence. In this study, contact with surfaces around patient, cleaning patient rooms and exposure at the triage or outpatient units were found to be associated with increased risk for COVID-19 infection in HCWs. The multivariable logistic regression in this study reveals that HCWs who had contact with surfaces around the patient had 2.3 folds increased risk of infection. To date, no strong evidence exists for transmission of COVID-19 through contaminated surfaces (fomites) [41]. However, SARS-CoV-2 viral RNA has been detected on surfaces in the immediate environments of infected patients, suggesting the environment as a potential route of SARS-CoV-2 transmission [42-45]. In the current study, cleaning patient room was significantly associated with increased risk of COVID-19 infection among HCWs. In addition, all the index cases were symptomatic on admission with possible viral shedding and contamination of their immediate surroundings. These two findings support the fact that fomite transmission might be the main route of infection in the current study. These findings were also supported by the high infection rates noted among cleaners and low cadre nurses (Nursing Aid and SECHNs). These staff are mostly responsible for cleaning patient rooms and changing of bed linens.

 

This study found that exposure at triage or outpatient units significantly increases the risk of infection. The transmission of COVID-19 among HCWs has been reported to occur in a variety of work departments within hospitals [10,27-30,46]. This finding has important implications for infection control at the triage or outpatient department as these units are the entry point to the hospital for all patients and visitors. HCWs at these units are therefore expected to apply at all times standard precautions including transmission-based precautions. Infection in HCWs could have occurred as a result of non-adherence to standard infection control practices including hand hygiene and use of appropriate PPE.

 

Hand hygiene is considered the most cost-effective intervention in preventing healthcare-associated infections including COVID-19. This study found that hand hygiene with ABHR or soap and water after each contact with the index patient was associated with a 60% reduced risk of infection. Most often transmission of SARS-CoV-2 from patients to HCWs occurs following contamination of HCW´s hands after either direct contact with the patients or contaminated surfaces. A retrospective cohort study conducted in a hospital in Wuhan, China found suboptimal hand hygiene before and after contact with patients to increase HCW risk by three folds [10]. Therefore to prevent infection in a healthcare setting, WHO recommends the use of contact and droplet precautions by HCWs caring for patients with COVID-19 [47]. The result of this study highlights the importance of hand hygiene in preventing healthcare-associated infections.

 

Despite consistent evidence supporting droplet infection and close contact with infected individuals as the primary route of COVID-19 transmission [48-52], this study found no association between close contact within 1 meter with index case and COVID-19 infection at the multivariable level. However, this association was significant at the bivariate level with a three-fold increased risk of infection in HCWs who had close contact (within 1 meter) with the index case. As all the index patients were symptomatic on admission, the possibility of droplet and close contact transmission cannot be ruled out in this study.

 

This study did not find any association with smoking or pre-existing medical conditions, most likely because the prevalence of smoking (3.9%) and pre-existing medical conditions (7.2%) was low in the study population. The study also found no association between COVID-19 infection with age or sex. A review on physician deaths from COVID-19 identified male gender, older age (57 years or older) and pre-existing medical conditions (hypertension, chronic lung disease, cardiovascular disease, immunosuppression and diabetes) as important risk factors for COVID-19 [53].

 

None of the HCWs reported exposure to any aerosol-generating procedures. Thus, the role of aerosol-generating procedures in the transmission of COVID-19 was not examined in this study.

 

This study has several strengths. First, the study was conducted immediately when the hospitals reported the index cases, thus minimizing the risk of HCW exposure in the community. Second, to determine risk factors for COVID-19 infection during patient care activities this study compared COVID-19 positive and negative HCWs. Third, exposed HCWs were immediately quarantined and tested twice by molecular method irrespective of symptoms during the 14 days follow up to determine infection status. This enabled an unbiased case ascertainment. Fourth, this was a prospective study and the questionnaires were administered immediately within a week after exposure. Thus the potential for recall bias was minimized.

 

This study also has limitations. First, this study did not use a serological method to determine infection status among HCWs, thus the full extent of infection cannot be ascertained. However, the high infection rate noted among HCWs could represent the true extent of infection. Second, the possibility of cross-infection among HCWs especially those that were asymptomatic in quarantine facilities cannot be ruled out. Third, whole-genome sequencing in specimen from HCWs and index patients was not carried out to determine the actual source of infection. Thus the study was unable to determine whether the overall infection rate was due to nosocomial or community transmission. Lastly, the small sample size could attenuate the magnitude of the association of some variables. Despite these limitations, our findings have important implications for infection control practices in healthcare settings in Sierra Leone.

 

 

Conclusion Up    Down

The secondary infection rate for COVID-19 among HCWs in this study was high, especially among cleaners and those exposed at the triage or outpatient units of the hospitals. Infected HCWs were mostly asymptomatic. This study identified contact with surfaces around patient, cleaning of patient room and exposure at the triage or outpatient unit to be significant risk factors for COVID-19 infection among HCWs in the study settings. This study further confirms that hand hygiene with ABHR or soap and water after each contact with a patient is effective in preventing nosocomial spread of COVID-19. Our findings emphasize the need for strict adherence to infection control measures, including the use of appropriate PPE, hand hygiene practices, and environmental cleaning and disinfection. Regular screening of HCWs for SARS-CoV-2 may enable timely detection of asymptomatic infections and prevent nosocomial spread of COVID-19.

What is known about this topic

  • Causative agents, signs and symptoms, risk factors for transmission and preventive measures
  • Some important risk factors for COVID-19 infection among HCWs in healthcare settings

What this study adds

  • The study estimated the infection rate among exposed healthcare workers in the study setting
  • Contact with surfaces around patient, cleaning of patient rooms and exposure at the triage or outpatient were also significant risk factors for COVID-19 infection among HCWs in the study settings
  • The study has important implications for infection control practices in healthcare settings in Sierra Leone and will be of interest to a wide global readership and potentially useful for other countries in the region that may be faced with nosocomial spread of COVID-19

 

 

Competing interests Up    Down

The authors declare no competing interests.

 

 

Authors' contributions Up    Down

Conceptualization and design of the study: JSS, DD, KMN, BK, SOS. Data collection, analysis and interpretation: JSS, KMN, BK, DD. Drafting of the manuscript: JSS, DD, KMN, CLN, SOS, DKA. Critical intellectual review and editing: KMN, ADA, DD, BK, CLN, DKA, MAV, EK, SOS. Finalization of the manuscript: JSS, CLN, DKA. All authors read and approved the final manuscript.

 

 

Acknowledgements Up    Down

We would like to sincerely thank the Bo, Port Loko and Kenema District Health Management Teams and the management of the Bo, Port Loko and Kenema Government Hospitals for granting the permission to carry out the study in their respective districts and facilities. Our profound gratitude to the research assistants for their dedication and commitment especially Albert A. Kamara, Abdulai Hashim Kamara, Chernor A. Kamara, Alpha M. Sheriff, Umaru Sesay, Francess jongopie, Albert J. Kallon, Peter Charles, Alex Bundor, Josephus Luseni, Abdulai S. Kamara and Aminata Thullah. We also thank all the healthcare workers who gave their consent to participate in the study.

 

 

Tables and figures Up    Down

Table 1: Demographic and exposure characteristics of study participants according to COVID-19 outcome status, Sierra Leone, 2020

Table 2: Patient care activities carried out by HCWs according to COVID-19 testing outcome, Sierra Leone, 2020

Table 3: Secondary infection rates of COVID-19 among exposed HCWs by demographic and exposure characteristics, SL, 2020

Table 4: Clinical characteristics of COVID-19 among infected HCWs, Sierra Leone, 2020

Table 5: Bivariate and multivariate analysis of factors associated with COVID-19 infection in HCWs, Sierra Leone, 2020

Figure 1: Process of identifying and recruiting HCWs into the study

 

 

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Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

Research

Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

Research

Risk Factors for COVID-19 infection among Hospital Healthcare Workers, Sierra Leone, 2020

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