Table 1.

Study characteristics.

No.	Study Characteristics and Summary Report
1	Author	Zhang et al. [21]
	Month/Year	April 2020
	Country	US
	Study Type	Observational study
	Measures	Syndromic Surveillance: A web-based mobile responsive HCW symptom screening application
	Results	Over a 7-day period, having quickly identified 0.36% symptomatic HCWs that otherwise could have come to work, increasing efficiency and effectiveness
2	Author	Hunter et al. [30]
	Month/Year	April 2020
	Country	UK
	Study Type	Observational study
	Measures	Testing: Testing of staff with compatible symptoms and conveying results rapidly via email
	Results	In 3 weeks, enabled 1414 (out of 1654) HCWs to return more rapidly to service
3	Author	Treibel et al. [3]
	Month/Year	May 2020
	Country	UK
	Study Type	Observational study
	Measures	Testing: Testing the asymptomatic HCWs especially during potential new waves of infection
	Results	Asymptomatic HCWs should be given easy access to testing, especially during new waves of infection
4	Author	Wee et al. [22]
	Month/Year	May 2020
	Country	Singapore
	Study Type	Observational study
	Measures	Syndromic Surveillance: Ongoing syndromic surveillance and centralized reporting of fever and ARI symptoms Testing: Testing the symptomatic HCWs if symptoms not resolve after 5 days Contact Tracing & Exposure Management: (1) Contact tracing conducted upon detection of a confirmed case; (2) Exposure risk assessment based on duration of contact, type of activity, and PPE use during the contact; (3) To test the exposed HCWs developing symptoms; to quarantine HCWs having significant unprotected exposure; to active monitor symptoms of the HCWs with low risk of exposure;
	Results	Over a 16-week period, 14 cases of HCW infection and 4 clusters detected After measures taken, zero nosocomial transmission detected Early detection having reduced quarantine of HCWs
5	Author	Garzaro et al. [23]
	Month/Year	May 2020
	Country	Italy
	Study Type	Observational Study
	Measures	Syndromic Surveillance: HCWs identified as low risk of exposure to self-monitor symptoms including cough, fever, dyspnoea, anosmia; Testing: Early testing enabling faster return-to-work thus alleviating staff shortages; Contact Tracing & Exposure Management: (1) Fast identification of contacts with the infected critical to lowering nosocomial transmission; (2) A structured risk-management for HCW exposure: (i) stratifying risks into high risk: presenting symptoms; moderate risk: exposure >15 min, or <2 m, without PPE; low risk: <15 min, or >2 m, with PPE; (ii) high risk HCWs to get tested and home quarantined; moderate risk HCWs to use surgical masks while awaiting the test results; low risk HCWs to self-monitor symptoms;
	Results	The monitoring measures having significantly reduced time between exposure, warning, and testing (p < 0.001)
6	Author	Rivett et al. [31]
	Month/Year	May 2020
	Country	UK
	Study Type	Observational Study
	Measures	Testing: Comprehensive testing of both symptomatic & asymptomatic HCWs
	Results	Data suggesting the true asymptomatic carriage rate being 0.5% Comprehensive testing of HCWs with minimal/no symptoms critical for protecting HCWs and patients
7	Author	Khalil et al. [32]
	Month/Year (Accepted)	May 2020
	Country	UK
	Study Type	Observational Study
	Measures	Testing: Universal testing of HCWs
	Results	34% positive HCW cases being asymptomatic while 59% symptomatic HCWs tested negative, indicating crucial needs for routine testing of all HCWs to (1) identify asymptomatic infected HCWs in an early stage, and (2) mitigate staff shortages due to unnecessary quarantine
8	Author	Flynn et al. [33]
	Month/Year	May 2020
	Country	US
	Study Type	Observational Study
	Measures	Testing: A drive-through testing model
	Results	The drive-through testing model having increased test efficiency, avoided long lines, conserved PPE
9	Author	Buchtele et al. [18]
	Month/Year	May 2020
	Country	Austria
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: Extensive contact tracing implemented among HCWs caring for immunocompromised patients, with all those having face-to-face contact with the confirmed case since the case’s onset of symptoms to get tested regardless of length of exposure
	Results	Extensive contact tracing and mass testing having prevented further spread of nosocomial transmission
10	Author	Ho et al. [50]
	Month/Year	May 2020
	Country	Singapore
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: RTLS-based (real-time location systems) contact tracing demonstrated having better validity than traditional EMR-based (electronic medical record) methods;
	Results	An integration of RTLS and EMR providing the best performance for contact tracing with a sensitivity of 77.8% and a specificity of 73.4%
11	Author	Yombi et al. [34]
	Month/Year	May 2020
	Country	Belgium
	Study Type	Observational Study
	Measures	Testing: Fever as a criterion for testing
	Results	Fever having a positive impact on the yield of PCR for SARS-CoV-2 (p < 0.001), using fever as a selection criterion resulting in more efficient screening
12	Author	Blain et al. [35]
	Month/Year	June 2020
	Country	US
	Study Type	Observational Study
	Measures	Testing: A test-retest strategy
	Results	11% asymptomatic HCWs with negative PCR results developing antibodies later in time Repeated testing effective in identifying asymptomatic infected HCWs
13	Author	Wang et al. [24]
	Month/Year	July 2020
	Country	Singapore
	Study Type	Observational Study
	Measures	Syndromic Surveillance: A comprehensive HCW sickness surveillance system: online reporting platform, medical screening, and testing for all the symptomatic HCWs Contact Tracing & Exposure Management: Exposure factors: serving in COVID-19 area/in non-COVID-19 area with known close contacts/in non-COVID-19 area with no known close contacts
	Results	Despite enhanced monitoring mechanism, no HCW was identified with infection, suggesting universal testing of HCWs not necessary for hospitals with adequate PPE protocol
14	Author	Villanueva et al. [36]
	Month/Year	July 2020
	Country	Philippines
	Study Type	Observational Study
	Measures	Testing: Criteria for testing: close contact with or high-risk exposure to a COVID-19 case, presence of symptoms Contact Tracing & Exposure Management: Categorizing exposure into high/medium/low risks based on duration of contact, PPE use, whether an aerosol generating procedure
	Results	Early screening for HCW infection having reduced nosocomial transmission
15	Author	Mehta et al. [17]
	Month/Year	July 2020
	Country	US
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: Aggressive contact tracing enabling the identification & monitoring of asymptomatic and/or pre-symptomatic HCWs
	Results	Aggressive and effective contact tracing providing greater yield than mass testing of every individual
16	Author	Kacmaz et al. [37]
	Month/Year	August 2020
	Country	Turkey
	Study Type	Observational Study
	Measures	Testing: rapid antibody testing
	Results	Reliability of antibody testing needing further validation but useful in COVID-19 screening among HCWs to evaluate IPC measures and prevent intra-hospital infection
17	Author	Tong et al. [38]
	Month/Year	August 2020
	Country	China (Mainland)
	Study Type	Observational Study
	Measures	Testing: A combination of PCR testing, serological testing, and radiological assessment conducted among HCWs caring for COVID-19 patients in the early stage of the outbreak
	Results	With the measures taken, no nosocomial infection detected
18	Author	Racine-Brzostek et al. [39]
	Month/Year	September 2020
	Country	US
	Study Type	Observational Study
	Measures	Testing: PCR + antibody testing
	Results	100% PCR positive HCWs tested positive for antibody testing High rates of seroprevalence suggesting the need for expanded PCR testing for HCWs
19	Author	Del Castillo et al. [40]
	Month/Year	September 2020
	Country	Italy
	Study Type	Observational Study
	Measures	Testing: Serological testing followed by PCR testing if positive to IgG
	Results	Serological IgG testing combined with PCR testing found to be a valid screening intervention
20	Author	Ho et al. [51]
	Month/Year	September 2020
	Country	Singapore
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: Utility of surveillance technologies such as RTLS and CCTV systems to enhance HCW exposure management
	Results	$\mathrm{Having}\mathrm{objectively}\mathrm{identified}55\mathrm{HCWs}\mathrm{with}7\mathrm{prolonged}\mathrm{exposures}(\ge$30 min), enabling more effective contact tracing than traditional methods
21	Author	Chong et al. [11]
	Month/Year	October 2020
	Country	Malaysia
	Study Type	Observational Study
	Measures	Syndromic Surveillance: HCWs with identifiable exposure risk under daily syndromic surveillance (self-assessment and self-reporting of symptoms through an online system) for 14 days since last exposure to an infection Testing: Targeted testing of close contacts Contact Tracing & Exposure Management: (1) Intensive contact tracing with identified close contacts having their exposure assessed and grouped into high/medium/low risk based on duration of exposure, presence of symptoms, PPE use, and whether an aerosol-generating procedure; (2) All close contacts to get tested and under daily symptom surveillance for 14 days; (3) HCWs with high risk exposure to be quarantined for 14 days; with medium risk 7 days; with low risk 2 days of sick leave
	Results	In a period of 5 months, 2401 risk assessments carried out among 1408 HCWs The surveillance program having limited nosocomial transmission, with a cumulative incidence of HCW infection of 0.3%
22	Author	Chen et al. [6]
	Month/Year	November 2020
	Country	China (Taiwan)
	Study Type	Observational Study
	Measures	Syndromic Surveillance: Centralized reporting of fever and ARI symptoms Testing: Testing the symptomatic Contact Tracing & Exposure Management: HCW exposure history reporting system
	Results	With the measures taken, no HCW infection detected
23	Author	Domeracki et al. [41]
	Month/Year	November 2020
	Country	US
	Study Type	Observational Study
	Measures	Testing: PCR cycle threshold (Ct) data used for HCW return to work (RTW) decisions
	Results	Initial Ct data significantly correlated with the time period between first diagnosis and RTW clearance (r = −0.80, p < 0.01), supplementing the dichotomized positive-or-negative PCR results
24	Author	Buising et al. [42]
	Month/Year	November 2020
	Country	Australia
	Study Type	Observational Study
	Measures	Testing: Frequent testing of HCWs and patients in wards with outbreaks and quick turnaround time for test results
	Results	Rapid and accessible testing enabling real-time outbreak management
25	Author	Coppeta et al. [25]
	Month/Year	December 2020
	Country	Italy
	Study Type	Observational Study
	Measures	Syndromic Surveillance: Exposed HCWs placed under an active syndromic surveillance program Contact Tracing & Exposure Management: Evaluating (1) distance from the infected, (2) duration of exposure, (3) the kind of medical service provided during the exposure, and (4) use of PPE
	Results	Typical symptoms presented in 92% HCW positive cases, but in only 33.3% negative cases (p < 0.01), suggesting symptoms being the best predictors of positive PCR results Close contact (within 2 m for more than 15 min) not statistically connected to contagion Use of mask significantly related to contagion (p < 0.01)
26	Author	Mullins et al. [43]
	Month/Year	January 2021
	Country	US
	Study Type	Experimental Study
	Measures	Testing: Parallel orthogonal testing of (1) Ortho Vitros Test, a commercial immunodiagnostic system, and (2) UMMC ELISA, a manually developed ELISA for total SARS-CoV-2 antibodies and full-length spike ectodomain protein
	Results	Positive predictive value: Ortho Vitros (82.2%), UMMC ELISA (100%) Negative predictive value: Ortho Vitros (100%), UMMC ELISA (99.9%) Parallel orthogonal testing of both demonstrated to improve the predictive value (+: 100%, −: 100%)
27	Author	Cheng et al. [26]
	Month/Year	March 2021
	Country	China (Hong Kong)
	Study Type	Observational Study
	Measures	Syndromic Surveillance: electronic syndromic surveillance system activated since the 1st imported case Testing: (1) PCR testing for symptomatic HCWs and HCWs classified as close contacts; (2) Repeated testing according to clinical assessment Contact Tracing & Exposure Management: (1) infection control team leading epidemiological investigation; (2) classifying the infected into hospital-acquired, community-acquired, and undetermined
	Results	Infection rate of HCWs (0.46‰) significantly lower than that of general population (0.71‰) (p < 0.01) No nosocomial transmission detected among HCWs
28	Author	Monsalud et al. [53]
	Month/Year	March 2021
	Country	US
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: (1) high-risk exposure HCWs (having participated in aerosol-generating procedures without adequate PPE; ongoing exposure to infected household members) required to self-quarantine and PCR testing; (2) low-risk exposure HCWs (all the other exposed HCWs) placed under surveillance
	Results	7.6% low-risk exposure HCWs identified as PCR-positive
29	Author	Wan et al. [52]
	Month/Year	March 2021
	Country	Malaysia
	Study Type	Observational Study
	Measures	Contact Tracing & Exposure Management: (1) contact tracing initiated once a COVID-19 case identified, collating info on the movement of the case 48 h before the onset of symptoms/diagnosis, forming a list of contacts; (2) level of risk of the contacts assessed and classified into different groups; (3) detailing management algorithm for low/medium/high-risk HCWs
	Results	Risk-based assessment with high sensitivity (100%) and specificity (72%) Risk categories and symptoms significantly correlated with positive cases (p < 0.001)
30	Author	Fernandes et al. [44]
	Month/Year	April 2021
	Country	Brazil
	Study Type	Observational Study
	Measures	Testing: PCR testing for the symptomatic HCWs and, if negative, a 2nd PCR test after the 5th day since symptom onset
	Results	The 2nd PCR testing having detected 4.9% of the positive cases
31	Author	Kolwijck et al. [45]
	Month/Year	April 2021
	Country	The Netherlands
	Study Type	Observational Study
	Measures	Testing: Antigen test for symptomatic HCWs, and (1) if tested positive, considered COVID-19 infection; (2) if tested negative, followed by PCR testing
	Results	The antigen-based testing strategy proved to be effective and easy to implement, with 72.5% sensitivity and 97% negative predictive value
32	Author	Lamb et al. [46]
	Month/Year	July 2021
	Country	UK
	Study Type	Observational Study
	Measures	Testing: Mass antigen testing for HCWs, followed by PCR testing if antigen tested positive
	Results	Antigen testing proven to be an effective screening tool, with a positive predictive value of 94.21%
33	Author	Azami et al. [47]
	Month/Year	July 2021
	Country	Malaysia
	Study Type	Observational Study
	Measures	Testing: PCR + serological testing Contact Tracing & Exposure Management: (1) Online questionnaire; (2) Evaluating risk based on HCWs’ occupational exposure and adherence to IPC practices
	Results	With measures taken, nosocomial infection having reduced, with an HCW infection rate of 0.5%
34	Author	Wee et al. [48]
	Month/Year	August 2021
	Country	Singapore
	Study Type	Observational Study
	Measures	Testing: Rostered routine testing for HCWs + mass screening of all inpatients
	Results	Enhancing early identification and contact tracing for HCW cases Significantly reducing the time infected inpatients spent in the general ward prior to isolation (p < 0.01)
35	Author	Diel et al. [27]
	Month/Year	October 2021
	Country	Germany
	Study Type	Observational Study
	Measures	Syndromic Surveillance: Exposed HCWs required to self-observe COVID-19-related symptoms Testing: Antigen testing every other day for exposed HCWs + additional PCR testing if one becoming symptomatic
	Results	Monitoring exposed HCWs with the measures in this study greatly reducing costs by 87.0%, compared with sending the exposed HCWs into quarantine
36	Author	Hong et al. [28]
	Month/Year	October 2021
	Country	US
	Study Type	Observational Study
	Measures	Syndromic Surveillance: HCWs confirmed with exposure registered for twice-a-day symptom monitoring for 14 days via email Contact Tracing & Exposure Management: Using electronic health record clinical event data (EHR report), in addition to traditional interviews, staff records, radio-frequency identification data, wifi access logs, bluetooth data, and etc. to enhance contact screening
	Results	22.2% exposures detected by EHR report, which would have been neglected based on traditional contact tracing methods
37	Author	Cordioli et al. [29]
	Month/Year	February 2022
	Country	Italy
	Study Type	Observational Study
	Measures	Syndromic Surveillance: Monitoring COVID-19 pathognomonic signs and symptoms Testing: Serological + PCR testing
	Results	Using a 3-diagnostic criterion (PCR + serological testing + pathognomonic presentation) to assess infection prevalence: COVID-19 prevalence varied based on different criterion: serological (6.7%), PCR (8.1%), serological/PCR (10.0%), pathognomonic presentation (9.6%), at least one of the above-mentioned criteria (17.6%) The probability of positive serological result decreasing by 1.1% every 10 days from the infection Data suggesting serological testing informative on infection susceptibility but not best for predicting previous infection
38	Author	Tande et al. [49]
	Month/Year	March2022
	Country	US
	Study Type	Observational Study
	Measures	Testing: Rapid antigen test for infected HCWs who meet the criteria to return to work, on the 5th day (or later) since symptom onset/diagnosis of COVID-19
	Results	The rapid antigen test, helpful to guide return-to-work decisions, having reduced isolation time by 2 days/person