Analysis of contact tracing surveillance for COVID-19 among healthcare workers in secondary referral hospital, Indonesia [version 1; peer review: awaiting peer review]

Background : Healthcare workers (HCWs) are more vulnerable to COVID-19 infection. Tracing and screening cases among healthcare workers are essential to overcome the spread of COVID-19. We held surveillance at the second-referral hospital in Surabaya, Indonesia, to inspect the associating factors of infected HCWs. Methods : From 776 HCWs, we conducted a structured retrospective review of all COVID-19-confirmed HCWs and ones having contact with COVID-19 patients between February-July 2021. We associated general characteristics (i.e age, gender, working sites, etc) of the sample with the positive cases, analyzed the vaccination status, Conclusions : Close contact, lack of compliance in wearing N95 masks, and unvaccinated status are risk factors for COVID-19 exposure to HCWs; thus, to achieve maximum prevention of intra-hospital transmission, the use of N-95 masks, contact avoidance, and vaccination, along with immediate tracing and strict health-protocols are all compulsory.


Introduction
COVID-19 has initiated worldwide outbreak inevitably threatening healthcare workers. High transmission rate of SARS-CoV-2 poses healthcare workers at risk whenever they are in contact with infected patients. 1,2 Globally, healthcare workers (HCWs) constitute nearly 7% of all COVID-19 cases. 2 A prospective cohort study of a large healthcare worker population in the USA and UK revealed more than three times higher risk of infection amongst HCWs than the general population. 3 In developing countries, the more HCWs get infected, the more disrupted health system will be. Several factors, e.g work department in hospital, duration of exposure, and PPE use have been shown to correlate with the risk of COVID-19 transmission. 1,4,5 However, many studies have reported the effectiveness of vaccine in reducing the incidence of hospitalized infections. Nevertheless, the SARS-CoV-2 mutation and various antibody put HCWs at risk for breakthrough infection, even after being fully vaccinated. [6][7][8] Therefore, comprehensive contact tracing has become one of the critical strategies by governments to ensure healthcare workers' and patients' safety. 9 Contact tracing is a crucial mechanism for breaking the chain of infectious diseases by identifying, quarantining, and monitoring contacts of infected individuals. 10 Contact tracing surveillance ensures detailed information about confirmed and suspected cases in the community. The growth of incidence can be controlled through effective contact tracing. More practical ways are needed to perform the screening and tracing process. 11 Digital applications or platforms have an excellent potential in implementing those steps efficiently without direct physical contact with infected individuals. [12][13][14] Infected HCWs commonly complain of fever, cough, shortness of breath, and sore throat. A study in Malaysia on tracing HCWs showed that the prevalence of healthcare workers infected with COVID-19 was around 0.3%. 15 In Indonesia, a study by Soebandrio et al. in Jakarta showed that of all 1201 healthcare workers, 7.9% were infected with regular symptoms such as cough, malaise, fever, shore throat, runny nose, and myalgia. 16 Since the pandemic is not yet over, we aim to portray the tracing system of COVID-19 staff in one of the teaching hospitals in Indonesia as a preliminary study to develop a mobile-based application as an innovation for the contact tracing process. We inspect and analyze several factors associated with COVID-19-confirmed HCWs.

Population studies
This study was conducted in a COVID-19 secondary referral hospital in Surabaya, Universitas Airlangga Hospital, Indonesia. In January 2021, Indonesia was in the middle of the first COVID-19 wave. The incidence declined from February until May and rose again in June-August 2021 as the second wave attacked. 17 Data in this study were collected retrospectively from the contact tracing surveillance database during February-June 2021 and associated general characteristics (i.e age, gender, working sites, etc) of the sample with the positive cases, regardless of the vaccination status (complete or incomplete). The database was composed of the online questionnaire filled out by healthcare workers suspected of having COVID-19 exposure during their work and signed informed consent prior to the study. It was developed and modified from a previous study database for specific healthcare workers. 18,19 Universitas Airlangga Hospital Ethical Committee had approved this study with the ethical clearance number: 174/KEP/2021.

Contact tracing procedure
Contact tracing was conducted by the Infection Prevention and Control Team. HCWs exposed to COVID-19-confirmed patients without appropriate personal protective equipment (PPE) were asked to fill in an online questionnaire to determine close contact with a confirmed case. The questionnaire comprised of the name, age, ward unit, date of contact, duration of contact, surrounding environment (indoor or outdoor), the physical distance between staffs, and PPE use. The use of personal protective equipment (PPE) refers to the National Guideline Recommendation. 20,21 The criteria for close contact were as follows: 1) If there was contact with the asymptomatic COVID-19 case two days before tested positive; 2) Contact with symptomatic COVID-19 case two days before symptoms appear; 3) Contact duration>15 minutes with a distance of ≤ 1.8 meters without proper PPE. Staff considered to have had close contact underwent quarantine and nasopharyngeal/oropharyngeal swab for SARS-CoV-2 detection ( Figure 1).

Statistical analysis
Contact tracing data will be shown as descriptive studies, including characteristics of HCWs such as gender, age, unit, and symptoms. We analyzed the data using SPSS version 24 (Chicago. Illinois. USA; RRID: SCR_002865). We analyzed general characteristics, including age, gender, working sites, close contact, contact duration, vaccination status, and other, then correlate them with infected HCWs. To calculate the risk value, we used chi-square in the two-category group. A simple logistic regression test was used to analyze the group of more than two categories. We carried out multivariate logistic regression analysis to see the interaction of factors from the characteristics of the sample, use of PPE, and vaccine status on the risk of COVID-19 infection in health care workers.

Results
There were 75.8% staffs filling out the surveillance form during the second wave which was thrice higher than at the end of the first wave. Sixty percent participants had close contact with infected persons during the second wave (see Table 1).    Table 2).
Below we present the distribution of personal protective equipment (PPE). HCWs who wore N95 masks and face shields were not likely to be positive (OR = 0.47; p = 0.003 and OR = 0.46; p = 0.025, respectively). On the other hand, patients that did not wear the PPE tended to be positive for COVID-19, although insignificant (see Table 3).

Discussion
Pneumoniae outbreak caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have caused pneumonia coronavirus disease (COVID-19), which spread rapidly throughout the world. 22 SARS-CoV-2 infection can be asymptomatic or cause mild to critical symptom. 23 The nature of the spread of the SARS-CoV-2 virus is still unclear, but what can be known is that prevention of its spread is related to demographic dynamics, population attitudes, and preventive measures. The outbreak in the Hunan area brought prevention movements in the form of non-pharmacological measures, restrictions on mobilization, screening of travelers, isolation, contact tracing, and quarantine. 24 A study by Yan Ge et al., illustrates that men were found more prevalent to have close contact with COVID-19 patients. Multivariable analysis based on age, sex, duration of contact, and contact setting on the incubation period, a person is more at risk of being infected with COVID-19 after 1-3 days of exposure to symptomatic COVID-19 patient (ARR [adjusted relative risk], 3.4; 95% CI, 1.9-5.8) or day 0 and 2 days after their index patient's symptom onset (ARR, 2.8; 95% CI, 1.5-5.0). The highest risk occurs both in the home setting and outside the home. Still, in the family cluster, this complaint will manifest 2-3 days after exposure. 25 The common transmission modes are conversation, eating in groups, direct contact in a closed room within close distance, in-hospital care, living together in one house, and sharing a vehicle. Multivariable analysis showed that family members had an ARR of 8.1 (95% CI, 5.9-11.4), contact with the same patient, and an ARR of 6.0 (95% CI, 1.7-21.0) compared to other distribution models such as conversation, sharing vehicles, and being in the same space. HCWs exposed to confirmed patients had lower scores than others but not statistically significant risk of COVID-19 (ARR, 0.4; 95% CI, 0.1-1.7). 25 Three retrospective cohort studies evaluated risk factors for the occurrence of COVID-19 in HCWs exposed to COVID-19. Seventy-two exposed people (clinicians and nurses) in Wuhan, China, had acute complaints.  increased risk of infection. Infected family members also tend to be the source of transmission for HCWs indicating that transmission can happen outside the hospital as well (RR, 2.76 [CI, 2.02 to 3.77]). 26 But our study showed that most of HCWs get infected after having contact with other medical staffs rather than patients, yet multivariate analysis revealed that the risk was not significant.
The Centers for Disease Control and Prevention (CDC) defines a person as close contact if the face-to-face distance is less than six feet, had contact two days before someone is COVID-19 confirmed, with a total duration of contact for 15 minutes. People who have had close contact are supposed to do the nasopharyngeal swab at least five days after close contact, isolate, and wear a mask as a measure to prevent transmission. 27 A meta-analysis study resulted in lower virus spread after applying 1 m distancing between people than < 1 m (n = 10 736, pooled adjusted odds ratio [aOR] 0.18, 95% CI 0.09 to 0.38; risk difference [RD] -10.2%, 95% CI -11.5 to -7.5; moderate certainty); because distance provides protection (change in relative risk [RR] 2.02 per m; interaction p = 0.041; moderate certainty). Face masks provided adequate protection by reducing the risk of infection (n = 2647; aOR 0.15, 95% CI 0.07 to 0.34, RD -14.3%, -15.9 to -10.7; low certainty), with more substantial power on HCWs using N95 or similar respirators than disposable surgical masks (e.g., reusable 12-16-layer cotton masks; p = 0.090; posterior probability >95%, low certainty). Goggle users also benefited from infection protection by reducing the risk of infection (n = 3713; aOR 0.22, 95% CI 0.12 to 0.39, RD -10.6%, 95% CI -12.5 to -7.7; low certainty). 28 In Indonesia, a study from Soebandrio et al. showed that six COVID-19 confirmed HCWs did aerosols procedure, and half of them did not use N95 masks. One of those six cases was hospitalized with pneumonia (16.7%). 16 Furthermore, our study disclosed that a lot of HCWs who did not wear any N95 mask, had close contact for duration > 15 minutes tested positive. This finding was supported by multivariate analysis showing its high significance for duration > 15 minute and wear N95 mask.
In Malaysia, of 1174 HCWs, 17 HCWs were tested positive for COVID-19 (12 HCWs had work-related exposure and 5 HCWs had community exposure-close contact) tested positive for COVID-19 presenting with fever (p < 0.001) and respiratory symptoms-cough (p = 0.003), shortness of breath (p = 0.015) and sore throat (p = 0.002). 15 In Indonesia, the most common clinical findings in infected were cough (61.6%), malaise (52.1%), fever (45.2%), sore throat ( In the period of December 14th, 2020-August 14th, 2021, complete vaccination with COVID-19 vaccines was 80% effective in preventing infection among HCWs. 30 Soegiarto et al examined total dose inactivated virus vaccination in health workers in Indonesia and disclosed that even fully vaccinated still had a breakthrough infection. 8 Our study showed similar result that the vaccined HCWs still have a risk to be infected. Our study comes with some limitations. We did the test simultaneously resulting in biased result-positive result in one work area, negative in another. Furthermore, we could not clearly identify the exposures leading to infection as an observational study. Data on PPE use were limited, self-reported, and did not include specifics on each item used (i.e suboptimal handwash). This study also did not consider family members who also had the infection. Therefore, other factors can be examined in further research.

Conclusion
Our study shows that close contact with COVID-19 patients, not wearing N95 masks, and not getting vaccinated are risk factors for HCWs to get infected with COVID-19. Therefore, adherence to N-95 masks, close contact avoidance, and complete vaccination are all mandatory. Proper and rapid testing is undoubtedly another key strategy in minimizing the spread of infection.