Publication - Advice and guidance

Coronavirus: how contact tracing works

Information from Scotland's Deputy Chief Medical Officer Gregor Smith.

10 Mar 2020
Coronavirus: how contact tracing works

A highly effective way to protect the public from infections like Coronavirus (COVID-19) is through a method called contact tracing. In Scotland this is delivered through NHS Scotland’s Test and Protect system.

Test and Protect has been operating since May 2020 and is doing what we need it to – identifying positive cases and tracing their close contacts so they can get appropriate public health advice to limit the spread of the virus.

Contact tracing is used to prevent the spread of infection, and to provide a rapid response to those who might be newly infected, by isolating potentially infectious individuals to prevent onward spread of the virus. It is a fundamental part of outbreak control, and is being used by public health professionals around the world to tackle the pandemic.

How does contact tracing work?

Those who test positive for coronavirus will speak to a Test and Protect contact tracer who gathers detailed information on places they visited and people they came into close contact with during, and up to 5 days prior to, the infectious period or, in the case of international travellers, since they arrived in the UK.

This builds a very specific picture of the people who need to be contacted and asked to self-isolate, such as family members, colleagues or fellow travellers.

Who is a close contact?

A close contact can be defined as someone living in the same household, someone who had direct or physical contact with an infected person for any length of time, or someone who has remained within two metres of the individual who has tested positive, for longer than 15 minutes.

People who have passed the person who has tested positive in the street, or in a shop, are at lower risk and will not necessarily be traced.

What about people who have travelled during the time they may have been infectious?

If there is a Scottish person who has recently been to another country or territory, and has tested positive, Test and Protect will notify public health authorities in the relevant country to investigate potential contacts and take steps to prevent further cases.

Equally, communication remains open with other parts of the world to discover if any positive cases in other countries might have spent time in Scotland, and require investigation around people they have had contact with.

What advice is given to close contacts?

Close contacts of positive cases are asked to self-isolate for 14 days to prevent onward spread of the virus.

Should a person develop symptoms while self-isolating, they should arrange to be tested. If they test positive, they must isolate for 10 days from the onset of their symptoms. If they test negative they must remain in self-isolation until the end of the original 14 day isolation period. This is because they could still be incubating the virus during this time.

Up to date information on self-isolation is available.

What is the evidence that contact tracing works?

It is a tried and trusted approach used for many years to prevent the spread of infection and to contain and stop outbreaks.

Contact tracing is an important part of epidemiologic investigation and active surveillance. For example, it is used to investigate cases and outbreaks of Tuberculosis, and the principles apply to any infectious disease.

Will contact tracing always be used?

This very much depends on the phase of the outbreak. These include:

  • contain – the early phase where we attempt to contain the spread by rapidly tracking down patients and giving the appropriate treatment
  • delay – taking steps to delay the peak of the outbreak, which could include reducing the number of large scale gatherings
  • mitigate – providing the best care for those who have become ill and supporting the delivery of essential services

The response to coronavirus is under constant review and informed by a range of public health experts and scientists.

Contact tracing may continue to successfully contain the virus, or we could reach a point of sustained transmission when we’d rely less on contact tracing, as happened in March 2020 when Scotland moved into lockdown following widespread community transmission of the virus. The focus then shifted to providing the best care to help those who have developed COVID-19, to delaying and reducing the spread as much as is possible and to protecting those who are particularly vulnerable.

Contact tracing is an integral part of Test and Protect, Scotland’s approach to delivering our Test, Trace, Isolate, Support strategy. It was rolled out across all health boards from May 2020 and is what is helping us break chains of transmission to control the onwards spread of COVID-19.

Why aren’t the public told exactly where confirmed cases are?

Patient confidentiality must be protected. People have rights to their own privacy and public services have responsibilities to respect those rights. Daily data is published by the Scottish Government for the whole of Scotland, which breaks down cases by NHS Board. Public Health Scotland is also publishing extended information, updated each day, with the latest available figures on coronavirus. This includes information at a neighbourhood level.

In line with data protection and patient confidentiality regulations, if you have tested positive your name and contact details will not be passed to others you have been in contact with, unless you have agreed to this. The interventions that contact tracing allows protect other people and mean we don’t have to share details with those who are not affected or at risk. 

Data gathered will be stored securely by NHS Scotland and safely destroyed as soon as possible after the pandemic.

What can I do to reduce the risk of being infected, or being identified as a close contact?

Our approach uses established, tried and tested contact tracing techniques, delivered by health protection professionals in teams within local NHS Boards, with support arrangements provided by the National Contact Tracing Centre.

However, Test and Protect is not a silver bullet. It is still essential for us all to continue with other measures to reduce transmission: physical distancing, hand and respiratory hygiene, and appropriate use of face coverings.

More information

NHS Inform has published public information on Test and Protect, and specifically on how the contact tracing process works in Scotland.

Health Protection Scotland has also published guidance for contact tracing of cases in complex and non-complex settings.

First published: 10 Mar 2020 Last updated: 20 Oct 2020 -