This section below summarizes scientific evidence and jurisdictional information regarding best practices for case and contact management of COVID-19. 

TThe public health approach to COVID-19 case and contact management to date has largely focused on interrupting chains of transmission through contact tracing by identifying individuals at risk of exposure to SARS-CoV-2 from an identified case. Case management includes a public health unit’s initial interaction with a positive case, the investigation to determine how they may have been infected with COVID-19, and the identification of all close contacts. The primary goal of contact tracing is to identify and to quarantine – or to facilitate self-monitoring of – individuals who are potentially exposed to a case to stop future chains of transmission.

The Government of Canada’s Interactive Data Visualizations of COVID-19 website was used to identify jurisdictions that have recently had lower COVID-19 case rates per capita than Ontario or jurisdictions that have maintained low COVID-19 case numbers despite the prevalence of the Delta variant. However, information identified from other jurisdictions was also included if available.

Limited information was identified on case and contact management addressing the transmission of the Delta variant and COVID-19 in general, as well as reported population health outcomes associated with using case and contact management.

Scientific Evidence

• Studies recommend using different digital technologies or multimodal (i.e., digital and non-digital) methods for COVID-19 case and contact management. One review noted the importance of isolation for both confirmed and probable COVID-19 cases.
  • Digital Technology: Digital technology is largely used to contact trace/manage cases:
    • A review (July 2021) from the National Collaborating Centre for Methods and Tools (NCCMT) identified the adoption of information technology (IT) infrastructure that respects data transparency and privacy as an important component found to contribute to the success of COVID-19 mitigation strategies.
    • A review (January 2021) found that repeated testing assisted in minimizing false COVID-19 diagnoses, while pooled testing was useful in resource-limited circumstances. The use of digital tools for contact tracing and isolation was identified as a best practice.
    • An article (February 2021) on case and contact management practices in Nigeria, Rwanda, South Africa, and Uganda identified leveraging IT as a best practice. For example, the Nigerian Centers for Disease Control and Prevention actively leveraged platforms such as social media and SMS messaging; and maintained a website replete with information, including locations of testing and isolation centres, informational flyers to post in health facilities and other institutions, and other messaging to counter misinformation.
  • Multimodal Methods: Digital technology can be used in tandem with, or used to enhance, non-digital methods of COVID-19 case and contact management:
    • A study (May 2020) examining Singapore’s contact tracing strategies identified a backward and forward activity mapping process to identify close contacts and examine a patient’s digital footprint, such as cloud-based visitor registration systems and mobile Bluetooth applications. The study suggests that digital contact tracing complements human-based contact tracing, and cannot replace the manual tracing.
    • An article (May 2021) noted that the Vietnamese Ministry of Health (MOH) instituted case-contact tracing from late January 2020, well before the World Health Organization (WHO) advised these measures. In addition, the identification, serial testing, and minimum 14-day isolation of all direct contacts of cases, regardless of symptoms, was central to their response. The MOH also instituted various digital methods. For example, on February 8, 2020, they established a technology-based communication plan, including videos and infographics disseminated through mass media, social networks, and digital platforms such as YouTube.
    • A study (June 2021) of the effectiveness of manual versus bulletin board contact tracing found that the latter: gives comparable results in terms of the reproductive number, duration, prevalence, and incidence; is less resource intensive; easier to implement; offers a wide range of privacy options; and can improve participation. Using both methods performs significantly better than manual contact tracing alone.
    • A UK study (August 2021) found that, relative to cases that were initially missed by the contact tracing system because of a data glitch, cases subject to proper contact tracing were associated with a reduction in subsequent new infections of 63% and a reduction in subsequent COVID-19-related deaths of 66% across the six weeks following the data glitch. These findings suggest that contact tracing may be an even more effective tool to fight infectious diseases than was previously thought.
    • A report from Public Health Ontario (July 2021) noted that strengthened laboratory surveillance, such as surge testing and contact tracing, and genomic sequencing are additional supports being used to suppress Delta variant transmission in England and Italy, which are jurisdictions where Delta is spreading fastest.
  • Inclusion of Probable COVID-19 Cases: The July 2021 review from the NCCMT found that comprehensive COVID mitigation strategies generally involved rapid isolation of both confirmed COVID-positive individuals and those with potential exposure.

International Scan

• Five case and contact management practices were identified internationally: mapping platforms (Czech Republic, Taiwan); public space record keeping (New Zealand [NZ]); vaccination status (Australia [AU], Wales); inclusion of probable COVID-19 cases (AU, Ethiopia, NZ); and contact categorization (AU, NZ). 
  • Mapping Platforms: Two jurisdictions use mapping platforms for case and contact management:
    • In March 2020, the Czech Republic began testing the “smart quarantine” project, which will map contacts of positive individuals using modern information technologies to help regional hygiene stations trace potentially infected people.
    • In July 2021, Taiwan’s Central Epidemic Command Center launched the Epidemiological Investigation Assistance Platform. The platform integrates and provides functions such as hotspot maps, tracking locations under investigation, and data from contact tracing text messaging service. Access is limited to authorized personnel in local government to conduct epidemiological investigations.
  • Public Space Record Keeping: In August 2021, NZ introduced mandatory record keeping for busy places and large gatherings. Those responsible for businesses (i.e., restaurants, bars, aged care) and events will need to ensure people keep a record when they visit, either by scanning QR codes with the Tracer App or making a manual record.
  • Vaccination Status: Australia and Wales (as of August 2021) require confirmed cases to isolate, regardless of vaccination status. In Wales, close contacts of confirmed cases that are fully vaccinated or are under 18 years of age are not required to isolate. The United Kingdom also does not require isolation for these individuals, in addition to those who cannot get vaccinated for medical reasons.
  • Inclusion of Contacts of Probable COVID-19 Cases: The World Health Organization (WHO; June 2021) recommends that all contacts of confirmed or probable SARS-CoV-2 infection quarantine in a designated facility or in a separate household room for 14 days from the last contact with the confirmed or probable case. Local health authorities may consider that contacts who have recent (within past three to six months) SARS-CoV-2 infection or who have received full vaccination may be at lower risk and be exempt from quarantine. While initial data appears to support this, WHO recommends countries adopt a risk-based approach for any decision to exempt individuals from quarantine.
    • Ethiopia (as of January 2021), NZ (as of August 2021), and AU (as of September 2021) only require self-isolation for contacts of confirmed cases.
    • US: The Centers for Disease Control and Prevention recommends contract tracing be conducted for contacts of both confirmed or probable cases. In Kansas and Illinois, isolation for contacts of probable cases is recommended.
  • Contact Categorization: Using contact categories to determine isolation requirements was identified in two jurisdictions. As of September and August 2021, AU and NZ, respectively, identified three tiers of isolation requirements for contacts of positive cases:
    • The first tier includes primary close contacts (AU) and close contacts (NZ), who are required to quarantine for 14 days following the last possible contact with a confirmed case, regardless of any negative test result. 
    • The second and third tiers differ between the two jurisdictions. The second tier includes contacts who had limited direct exposure with a confirmed case. Contacts are required to isolate and get tested in NZ, but were only required to be informed of their exposure in AU. AU’s third tier is a close contact of a close contact, and some Public Health Units may require them to quarantine. NZ’s third tier is casual contacts, who have been in the same place as the confirmed case but may not have been near the person, and recommends self-monitoring for symptoms for 14 days.

Canadian Scan

• Four types of case and contact management practices were identified in Canada which include: vaccination and infection status (Nova Scotia [NS], British Columbia [BC], New Brunswick [NB], Newfoundland and Labrador [NL]); inclusion of probable COVID-19 cases (Prince Edward Island [PEI], NS), and public space record keeping (NS, BC). Changing case and contact management based on vaccination status was the most identified practice.
  • Vaccination and Infection Status: Most identified Canadian provinces changed their case and contact management based on an individual’s vaccination status. The Public Health Agency of Canada (PHAC) recommends that fully vaccinated individuals not be required to self-isolate, unless symptoms occur.
    • Fully vaccinated and/or recently infected (i.e., within 90 days) contacts are not required to self-isolate in NS and BC. In NB, contacts are not required to self-isolate if fully vaccinated, and if contacts are symptomatic, they are required to get tested. A symptomatic contact is only recommended to get tested in NS. As of March 2021, vaccination history does not change case or contact management in NL.
  • Inclusion of Probable COVID-19 Cases: Some provinces include contacts of probable cases in their contact management, while others only include confirmed case contacts. While PEI includes contacts of both confirmed and probable cases in their contact management, NS only considers contacts of confirmed cases. In Alberta, close contacts of confirmed cases are not required to isolate, and contact tracers from public health units do not inform them of their potential exposure.
  • Public Space Record Keeping: Nova Scotia (no date) uses public space record keeping in their case and contact management. Restaurants and liquor licensed establishments are required to collect contact information (i.e., date/time of visit, phone number) for all dine-in patrons for 30 days for contact tracing. Patrons can be fined $2,000 for providing false information. A literature review from the BC Centre for Disease Control (June 2021) notes that administrative controls, including recording visitor details, have been generally successful in avoiding workplace outbreaks.

Ontario Scan

• Ontario’s case and contact management strategies include: isolation requirements being determined by vaccination status and symptom presentation; and multimodal methods.
  • Vaccination Status and Symptom Presentation: The Government of Ontario (August 2021) manages potential COVID-19 cases based on vaccination status and symptom presentation.
    • Isolation for fully vaccinated and/or previously positive individuals is recommended if symptomatic and is not required if asymptomatic. If living with a symptomatic individual, household members are required to self-isolate until the symptomatic individual receives a negative COVID-19 test result, unless the household member is asymptomatic and fully immunized or previously positive.
    • If not fully immunized nor previously positive, asymptomatic individuals with high-risk exposure to a confirmed or probable case should self-isolate while test results are pending and complete their full 10-day self-isolation in the event of negative test result(s). Household members of asymptomatic individuals who do not have a high-risk exposure do not need to self-isolate while the asymptomatic individual is awaiting screening testing results.
  • Multimodal Methods: In March 2021, Toronto Public Health (TPH) transitioned to a new enhanced case and contact management system, allowing lab results to be available more quickly through frequent automatic uploads and for access data in a centralized location. Valuable staff resources are accordingly then focused on critical management functions. In addition, TPH introduced a virtual assistant (VA) tool to administer a rapid-response questionnaire to both cases and contacts, and to gather critical data, including symptoms, onset date, ability to self-isolate, risk factors and contacts. TPH built the infrastructure such that from June 2-4, 2021, TPH successfully reached 97.2% of newly reported confirmed cases of COVID-19 within 24 hours and 83.7% of newly reported contacts within 24 hours. 

The COVID-19 Evidence Synthesis Network is comprised of groups specializing in evidence synthesis and knowledge translation. The group has committed to provide their expertise to provide high-quality, relevant, and timely synthesized research evidence about COVID-19 to inform decision makers as the pandemic continues. The following member of the Network provided an evidence synthesis product that was used to develop this Evidence Synthesis Briefing Note:

• Ontario Health (Cancer Care Ontario), COVID-19 Case and Contact Management: Jurisdictional Scan Results, 10 September 2021.