A Review of Contact Tracing Approaches for Controlling 1 COVID-19 Pandemic 2

The year 2020 will always be in the history of mankind due to the deadly outbreak of 9 COVID-19. Many people are already infected around the world due to the spreading of this 10 novel coronavirus. The virus mainly replicates through close contacts, so there are no other 11 alternatives than to keep social distance, use proper safety gear, and maintain self-quarantine. 12 As a result, the growth of the virus has changed the lifestyle of every individual to a great 13 extent. It is also compelling the Governments to dictate strict lock-downs of the highly 14 affected areas, impose work-from-home approaches where applicable, enforce strict social 15 distancing standards, and so on. Some of the countries are also using smartphonebased 16 applications for contact tracing to track the possibly infected individuals. However, there is a 17 lot of discussion around the world about these contact tracing applications and also about 18 their architecture, attribute, data privacy, and so on. In this paper, we have provided a 19 comprehensive review of these contact tracing approaches in terms of their system 20 architecture, key attributes, and data privacy. We have also outlined a list of potential 21 research directions that can improvise the tracing performance while maintaining the privacy 22 of the user to a great extent. 23


Introduction
he World Health Organization (WHO) has declared COVID-19 as a public health emergency of international 27 concern (PHEIC) on January 30, 2020 [1,2] and also a pandemic on ??arch 11, 2020 [3]. According to the 28 Coronavirus disease (COVID-19) Situation Report (by WHO) on 11 July 2020, the total number of confirmed 29 cases was 12322395 globally and among them, 556335 was deceased [4]. To defend this virus, there should be 30 rapid identification and forced quarantine of the infected persons, determination of every other individual with 31 whom they have had close contacts, and the locations where the infected person has visited in recent days [5]. 32 For that reason, many countries have already developed different contact tracing apps to track infected persons 33 and zones [6]. 34 These apps are designed to counterpart contact tracing by using location data acquired from GPS (Global 35 Positioning System) and Bluetooth sensor [7]. Through these applications, it is possible to detect whether a 36 user has been exposed to any COVID-19 positive person or not. Although Bluetooth based solutions for contact 37 tracing are found alluring and being used in developed countries e.g., Singapore, South Korea, etc., there are some 38 negative impacts as it may hamper one's privacy [8,9]. Besides, any intruder may impersonate and steal valuable 39 information while using the Bluetooth based application. Here, the above-stated solution requires Smartphones 40 to operate. But according to [10], only 24% of people in India use a smartphone. As a result, the BLE (Bluetooth 41 Low Energy) based solutions will not be appropriate for a list of countries. To   China has also launched an application titled "Health Code" [21]. The app collects several information about the 86 user such as work address, residential information, contact number, passport number, national identity number, 87 symptom, travel history, and so on. Once submitting the required data, verification will be done via the 'QR

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Code' which will be sent to the mobile phone. The QR Code can contain either red, green, or amber color code, 89 and depending on the color code the user will be considered risky or risk-free. Users with red color code will be 90 considered risky and will undergo government quarantine or self-quarantine for 14 days, users with amber code 91 will go to quarantine for 7 days but users with green code are considered to be riskfree. voluntarily download the app for tracing and notifying users who may have been exposed to COVID-19 carrier.

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The public health officials of Alberta Health and Alberta Health Services (AHS) use this application to supplement 99 manual contact tracing. "ABTraceTogether" is also a Bluetooth technologybased application which tracks user's 100 2 10.34257/GJCSTHVOL21IS1PG31 mobile device. It generates an anonymous log of other app users with whom the device user has been in contact.

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Here the mobile devices exchange Bluetooth-enabled secure encrypted tokens when they are in close contact. The 102 logged data that is collected by Bluetooth proximity is anonymized and encrypted, and does not reveal users' In the Geo-location-based approach, the location data of the COVID-19 carrier will be collected from the SIM 190 (Subscriber Identity Module) operator rather than any installed application. The main advantage is that to trace 191 the COVID-19 carrier, no user application is needed. But in this approach active government support is required.

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The summarized steps are as follows: Fig. ?? illustrates the summarized steps of the cellphone network-based for example when a user is using a public bus or entering a shopping mall and so on. in this approach, it is 199 also instructed that even if the user has no smartphone, the QR code must be printed in hard copies. QR code