Phase 1: Paper-based workflow—March 2020
The first contact tracing of SARS-CoV-2 at Marburg University Hospital was performed in March 2020 only weeks after the first confirmed positive cases had appeared in Germany. Initially, the division of infection control was provided with handwritten lists of telephone numbers belonging to HCWs who probably had contact with detected index cases. ICPs then had to chase reported contacts on the phone to identify further contacts and assess their individual risk of developing SARS-CoV-2 infections. Contacts were advised to get a PCR-test by a nasopharyngeal swab on day 1 and day 5. Depending on contact intensity they were told to preventively self-isolate at home and wait for to the local health authorities to contact them and to evaluate the need for quarantine. The results of the PCR tests had to be actively pursued by the ICP through the laboratory information system (LIS). Contact patients were identified separately using the hospital information system (HIS). This very time consuming process, which was primarily manually oriented, quickly reached its maximum possible capacity in the course of the SARS-CoV-2 pandemic in early 2020.
Phase 2: Computer-based workflow—April 2020
In order to accelerate the workflow, we implemented a standardized paper-based contact form that could be downloaded from the hospital intranet. Contacts among HCWs had to identify themselves autonomously, fill out the form and send it to the division of infection control. Contacts among patients still had to be identified separately using the HIS. Unfavorably, forms also reached the division of infection control in multiple ways, making it necessary to further standardize the input and transfer it for the electronic processing of contact lists. Therefore, this workflow might have omitted the time-costly, telephone-based retrieval of contacts but contacts still had to be informed and instructed separately. Soon, it became apparent that this computer-based workflow would not be feasible in a phase of higher emergence of infections due to a shortage of IT support and standardization. Altogether the limitations of the computer-based workflow led to the development of an intranet-based workflow (Phase 3) that was implemented in May 2020.
Phase 3: Intranet-based workflow—May 2020
As soon as a new SARS-CoV-2 index case was reported, it was assigned to an ICP. To ensure efficient contact tracing, the ICPs proceeded according to a standard operating procedure (Fig. 1). The ICP called the direct supervisor or the head nurse of the affected section to inform them about the new index case and planned infection control measures including screening regime. Additionally, a standardized e-mail was sent to each affected unit containing information about the newly detected index case, the necessary infection control measures and a link to the intranet-based contact form. Attached to this email, a list with all different occupational groups and functional areas of the hospital is sent to the recipients to subsequently identify and inform incorrectly and not-yet identified contact persons and groups.
The intranet based workflow comprised a form with checkboxes for index case, contact duration, kept distance, worn PPE (e.g. face mask, respirator), and input boxes for personal data and existing symptoms. As soon as the relevant information was submitted, the ICP-team received an e-mail notification for every new contact. The case-ICP was then able to access all necessary information in the form of a table listing all contacts among employees for a specified index case.
High risk contacts (e.g. symptomatic people, or people with long close contact without wearing PPE) were automatically highlighted by an algorithm to accelerate proceedings. Thus, ICPs could rapidly identify high risk contacts and act consequently (e.g. isolation of contact patients, separation of staff contacts).
Other contacts were evaluated according to our internal risk classification (Fig. 2) which was based on the recommendations of the Robert-Koch-Institute (RKI) but designed more straightforward in order to consider the special circumstances of a university hospital [24] (Fig. 2). Additionally, ICPs had to answer to following questions, to take appropriate infection control measures depending on the individual risk assessment:
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(a)
Is the new index a patient or a hospital employee?
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(b)
If it is a patient, is he/she still admitted? If yes, since when? Is he or she isolated?
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(c)
If it is an employee, is he/she working at the moment? If yes, in which clinic or section?
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(d)
Is the index symptomatic? If yes, since when?
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(e)
Do we have preexisting test results (PCR, antigen test)? If yes, what and from when are they? How are ct value and ct course?
Contacts among patients were traced separately using the HIS before they were added to the contact list. In Germany, it is legally obligated, to provide the local public health authorities with personal data of close contacts. To ensure data protection requirements, the generated lists were uploaded to a protected cloud system which was operated by the local authorities.
Phase 4: Intranet-based test regime—October 2020
Once rapid POCTs were available in Germany, the tests became part of our contact tracing and testing procedure. Our objective was to decrease time to result and increase testing capacity. In order to control a possible viral spread, it is crucial to get results as soon as possible after testing. Hence hospital employees were tested at least three times every 48 h after last contact to the index case by using SARS-CoV-2 Rapid Antigen Test (Roche, Basel, Switzerland). For contacts among patients or symptomatic contacts the same schedule was applied, but testing was performed via PCR. Additionally, positive rapid POCTs had to be confirmed by PCR. To ensure data protection, an anonymous barcode with a personal-ID-number was generated for every HCW who filled out the intranet-based contact form. Without a barcode, HCWs couldn’t get tested at the clinic’s test center. POC screening results were automatically submitted via the intranet-based tool and displayed in the contact tracing list. PCR results had to be reviewed manually as they were not linked to the contact tracing tool. Results were reviewed by the case-ICPs on a regular basis. This way, it also came to our attention if a specific employee had not yet used their barcode for testing. In addition, the tested employees were able to retrieve their test results by entering their ID-number into the intranet tool. The tool provided the division of infection control with all important information at any time by directly linking the POCT results to a contact person while also having information about index case and the individual risk assessment available. It therefore facilitates rapid identification of positive contacts among employees, continuous evaluation of the ongoing infection process and assessment of the efficacy of outbreak control measures.
To keep the threshold for hospital staff to be tested as low as possible, a second web-based form for voluntary SARS-CoV-2 testing was implemented in October 2020. Using this form enables HCWs to generate barcodes for testing without having been in contact with a SARS-CoV-2 case in the hospital setting or without any other reason. This form facilitates testing for various private reasons and for intermittent routine tests, for example. The tracing lists are similar to those used for contact tracing, but they do not include data on index cases or contact data and are followed up on separately by the ICP.
Personalized data from the web-based contact tracing was accessible for the IPCs only until 14 days after entry using a password-protected interface. HCWs can call up their individual screening results anonymously for an unlimited period of time via a query mask in the hospital intranet by using an individualized code they had received after entry in the contact tracing mask.
Only non-personalized data on the number of contacts, the duration of the contact, the time of the contact and the date of test results were used for retrospective analysis of the POCT workflow effectivity and in purpose of this report. The statistical analysis of our data was performed using SPSS (IBM, Armonk, USA).