Test, Trace, Protect (contact tracing for coronavirus (COVID-19)): up to 12 March 2022
Management information update on contact tracing delivered as part of the Test, Trace, Protect strategy in Wales up to 12 March 2022.
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In this page
Main points
In the latest week (6 to 12 March 2022):
- there were 24,068 positive cases eligible for follow-up, of which 21,285 (88.4%) were reached and asked to provide details of their close contacts
- there were 31,063 close contacts eligible for follow-up; of these, 26,274 (84.6%) were reached and advised accordingly, or had their case otherwise resolved
- 23,002 (74.0%) of the close contacts were household contacts, of which 19,552 (85.0%) were reached and advised accordingly, or had their case otherwise resolved
- there were 1,832 positive cases and 3,411 close contacts not eligible for follow up
In total, since 21 June 2020:
- there were 903,934 positive cases that were eligible for follow-up, of which 839,106 (92.8%) were reached and asked to provide details of their recent contacts
- there were 1,460,352 close contacts eligible for follow-up; of these, 1,313,879 (90.0%) were reached and advised accordingly, or had their case otherwise resolved
- there have been 108,822 positive cases and 161,063 close contacts not eligible for follow-up
This data is management information provided to the Welsh Government by the NHS Wales Informatics Service. We are publishing this to provide a weekly summary of contact tracing activity in Wales during the coronavirus (COVID-19) pandemic. This data has not undergone the same level of quality assurance as official statistics and the data may be subject to future revisions.
Analysis
Chart 1 shows the daily number of positive cases and close contacts eligible for follow up. Variation between days reflects differences in demand on the system (for example the number of tests performed). More information is given in the quality and methodology section of this report.
The highest number of positive cases (71,201) and close contacts (53,043) eligible for follow up were both seen in the week starting 1 January 2022. The combined total of 124,244 positive cases and close contacts was significantly higher than at any other time during the pandemic. Subsequently; cases and contacts eligible for follow up have fallen to levels similar to the pre-Omicron wave.
Up to early 2022 the number of positive cases eligible for follow-up followed a similar trend, though at a slightly lower level, to the number of PCR cases reported by Public Health Wales (PHW) on its daily surveillance dashboard. The lower numbers here reflect that some cases are not eligible for follow-up, for example cases in closed setting such as hospitals. By mid-January 2022 the total here was higher than the PHW figure for daily PCR positive cases, due to a fall in PCR testing after an announcement that PCR follow up tests were no longer required after a positive LFD. LFD cases were still included for contact tracing purposes. Public Health Wales has been publishing lateral flow test reports, including the number of new positive cases, separately since March 2021.
Time taken to reach positive cases and close contacts
Throughout the pandemic, there is a correspondence between the overall burden on the contact tracing system and the time taken to reach close contacts. Significant increases in cases and contacts correspond to reductions in the proportion reached within 24 and 48 hours.
Positive cases
In the latest week (6 to 12 March 2022):
- of the 24,068 positive cases that were eligible for follow-up, 39.6% were reached within 24 hours of referral to the contact tracing system; this equates to 44.8% of those reached being reached within 24 hours
- 71.7% of positive cases that were eligible for follow-up were reached within 48 hours; this equates to 81.0% of those reached being reached within 48 hours
Close contacts
In the latest week (6 to 12 March 2022):
- of the 31,063 close contacts that were eligible for follow-up, 59.4% were reached within 24 hours of being identified by a positive case; this equates to 70.3% of those reached being reached within 24 hours
- 80.9% of close contacts that were eligible for follow-up were reached within 48 hours of being identified by a positive case; this equates to 95.6% of those reached being reached within 48 hours
In the latest week (6 to 12 March 2022):
- from the time positive cases were referred to the contact tracing system, 25.8% of close contacts that were eligible for follow-up* were reached within 24 hours; this equates to 30.4% of those reached being reached within 24 hours
- from the time positive cases were referred to the contact tracing system, 59.8% of close contacts that were eligible for follow-up* were reached within 48 hours; this equates to 70.6% of those reached being reached within 48 hours
Close contacts that become positive cases
This section looks at close contacts who go onto have a positive test within 7 days of referral to the contact tracing system.
In the latest week, of the 24,068 positive cases that were eligible for follow up 2,928 (12.2%) had been identified as close contacts of other positive cases in the previous 7 days. Of these, 2,644 (90.3%) had been reached by contact tracing teams and advised accordingly.
In total, since 21 June 2020, of the 903,934 positive cases 121,693 (13.5%) had been identified as close contacts in the previous 7 days. Of these, 109,951 (90.4%) had already been reached by contact tracing teams and advised accordingly.
The proportion of positive cases identified as close contacts of previous positive cases has been changeable over the course of the pandemic. It has ranged from around 5% to over 30% at different points since the contact tracing system was fully established by the end of the summer in 2020. The highest proportion was in April 2021, when case rates were very low. The falls in December 2020 and December 2021 correspond to sharp increases in case rates.
Timeline of events effecting these statistics
Data for 1 to 21 June 2020
Early reporting, covering the first three weeks of contact tracing in Wales, was based on data reported by local and regional contact tracing teams prior to the introduction of the national digital system.
In Wales, during the period from 1 to 21 June 2020, 1,905 positive cases were referred to local and regional contact tracing teams. This resulted in 2,616 contacts identified for follow-up, of which 2,117 were reached and advised accordingly.
There will be a small amount of overlap in the reporting from the national digital system and the early reporting provided by local and regional contact tracing teams. For this reason we would not recommend combining figures from the two different reporting streams. Cumulative reporting in this and future versions of this release will focus on data from 21 June 2020.
17 December 2020
On 17 December 2020, the NHS Wales Test Trace Protect (TTP) service rolled out a new function aimed at giving people the ability to provide details of their close contacts via a new e-form. Cases receive an initial phone call from contact tracers to invite them to complete the e-form and this call is defined as a successful contact. This information is included in the data shown in this release and will have an impact on the overall percentage of both positive cases and contacts reached, and the percentage of positive cases and contacts reached within 24 and 48 hours. Due to the reduction in positive cases in Wales and therefore, lower numbers of cases and contacts currently requiring contact tracing, most local contact tracing teams are prioritising phone calls over the use of the e-form. This means that e-forms will account for extremely small numbers within the data presented in this publication. We continue to work with colleagues to monitor use of the e-form within the contact tracing system and will include further information on this if use of the e-form begins to increase considerably.
4 March 2021
From the 4 March 2021 publication, data for travellers arriving from outside the UK’s Common Travel Area is no longer included in the figures presented in this release and has been removed retrospectively from historic data. Compared to the data as it was published on 25 February 2021, this resulted in a small reduction in the number of positive cases and close contacts in the data published on 4 March 2021 as these arriving international travellers represented less than 3% of the weekly cases. These citizens are isolating due to their travel and to avoid any potential transmission of variants of concern. As such they are subject to a separate managed quarantine process. If an arriving international traveller subsequently tests positive, they will then become a positive case and therefore be subject to the full contact tracing process and appear in the statistics presented.
13 March 2021
School “bubble” contacts aren’t subject to formal contact tracing process, as they are contacted directly by their school and provided the necessary public health and isolation guidance. For this reason, from the release published 25 March 2021 we have excluded these contacts from the close contacts statistics presented in this release. All historical data has been updated to reflect this change.
Positive cases will most likely have close contacts outside of their bubble which have been generated in school which will be communicated to local contact tracing teams and will be eligible for follow up, these contacts remain in the statistics presented in this release.
Data presented in this release is broadly comparable with publications prior to the 25 March 2021, though we advise against using the publications on 11 February and 18 February 2021 to make comparisons, where the issues in the school 'bubble' data have had the most effect, and the publication on 23 March 2021 where all school contacts were removed while we investigated a data quality issue. Comparisons can be made within the time series data in this release where school 'bubble' data has been removed throughout.
Information and guidance on how schools and settings can continue to make their sites as safe as possible for staff and learners, including school “bubbles” is outlined in the Operational guidance for schools and settings.
21 March 2021
For the week 21 to 27 March 2021, there was a large increase in the number of contacts eligible for follow up in Swansea Bay University Health Board which can be seen in the associated tables published alongside this release. We believe this to be a result of some school contacts being uploaded incorrectly for this region. This increase had a small impact on the national figures presented in this release for the percentage of contacts reached but a larger impact on time taken to reach close contacts. Regions have been reminded of the guidance on uploading school “bubbles” into the system to avoid further issues with the data.
2 May 2021
In the 17 May 2021 release, Digital Health and Care Wales (DHCW) changed the contact tracing data to remove duplicate records. This change was applied to historical data from the start of this dataset (21 June 2020) onwards. Duplicate records occur where more than one positive case identifies the same close contact. Following this change, close contacts are now only counted once in the figures eligible for follow up. Previously they were counted each time they were identified by a positive case. Duplicate records account for up to 5% of the eligible close contacts in each week.
16 May 2021
When close contacts are identified by a positive case outside of Wales or through the NHS app, these are inputted into the system manually as the positive case that identified them does not exist in the Welsh contact tracing system. As the positive case is not in the Welsh contact tracing system, these close contacts should not be included in the timeliness measure from the time positive cases are referred to the contact tracing system. We were recently made aware of the processes around these close contacts and from the week commencing 16 May 2021, we have removed these close contacts from this measure and the historical data to more accurately reflect the contact tracing system. As these close contacts are eligible for follow up within the Welsh contact tracing system, they still appear in all other figures relating to close contacts presented in this release.
The percentage of close contacts reached within 24 hours and 48 hours from the time positive cases were referred to the contact tracing system will appear higher than previous publications as a result of this change. Since September 2020 when the process for these close contacts was implemented, there have been an average of 60 close contacts per week identified by a positive case outside of Wales or through the NHS app. For the week 16 to 22 May 2021 when this change in methodology was first implemented, the change resulted in an increase of 6 percentage points in the timeliness measure within 24 hours and 7 percentage points in the timeliness measure within 48 hours from the time positive cases were referred to the contact tracing system.
7 August 2021
As of 7 August 2021, adults who have been fully vaccinated and received the vaccine in the UK and those under the age of 18 no longer have to self-isolate if they are identified as close contacts of someone who has tested positive for COVID-19. Close contacts are still contacted by the contact tracing team and are therefore still included in the statistics presented in this publication.
6 September 2021
Due to an increase in the number of positive cases and contacts eligible for follow up by local contact tracing teams, from the week commencing 6 September 2021 Welsh Government introduced a national framework to prioritise cases that have a higher risk of onward transmission or that involve
10 October 2021
Issues were identified at a private laboratory based in Wolverhampton, England where incorrect test results had been issued. As a result of this, a number of people tested between 4 and 12 October were advised to re-test which may impact the number of positive cases eligible for follow up in the weeks beginning 10 and 17 October 2021. Around 4,000 tests are estimated to be affected in Wales, more information is available in the statement from the Minister for Health and Social Services.
29 October 2021
As of 29 October 2021, the self-isolation criteria have been updated for household contacts who are fully vaccinated or aged between 5 and 17.
As policy changes regarding the operation of the contact tracing system we continue to work with colleagues in DHCW to determine data quality and possible further breakdowns of the data.
September/October 2021
From early September to the end of October 2021, the ‘percentage of positive cases reached within 24 and 48 hours’ timeliness measures were generally lower compared to the first half of 2021. This is likely due to a larger number of positive cases and close contacts eligible for follow up by local contact tracing teams.
Test, Trace, Protect (contact tracing for coronavirus (COVID-19)) data
Number of positive cases and close contacts eligible for follow-up by local contact tracing teams on StatsWales
Figures show the number of positive cases and close contacts eligible for follow-up by local contact tracing teams. The data represents the number of eligible cases introduced into the contact tracing system by day.
Number of positive cases eligible for follow-up by local contact tracing teams, by Local Health Board on StatsWales
The data represents the weekly number of eligible cases introduced into the contact tracing system by local health board.
Number of close contacts eligible for follow-up by local contact tracing teams, by local health board on StatsWales
The data represents the weekly number of close contacts eligible for follow-up by local health board.
Glossary
Eligible for follow-up
The majority of cases not eligible for follow-up by local contact tracers occur in closed settings such as hospitals, care homes and prisons. These cases are escalated to regional teams for onward management.
Positive cases and close contacts that are resident outside of Wales are also not eligible for follow-up by local contact tracing teams. Public Health Wales refer these cases to the relevant public health agency for onward tracing. These cases would have been included in the numbers eligible for follow-up in statistical releases prior to the 10 September 2020.
Successfully reached
It may not be possible to trace all individuals referred to the contact tracing service. For various reasons contact details will not have been provided for some individuals and others may not have responded to calls, texts or emails from tracing teams. The proportion of positive cases that were eligible for follow-up and that were reached only include those cases that were reached but does not include those cases where local tracers have made an attempt, but failed, to contact.
Timeliness measures
The date and time that a positive case or close contact was reached is taken to be the earliest of a number of events captured in the system. These include:
- successful phone call record (including initial phone call from contact tracers to invite cases and contacts to complete the e-form)
- completion of the contact interview
- first daily check-up
- close contacts or other exposures being entered into the contact tracing system (for positive cases only)
- case marked as ‘resolved’
These events have been chosen as they all indicate that a contact tracer has successfully been in touch with the individual. The range of events is necessary because phone call records do not exist for all positive cases and close contacts. This may arise, for example, where multiple cases live in the same household and the information is captured through a single phone call, rather than one for each individual.
Close contacts ‘otherwise resolved’ covers a small number of instances where the same contact is identified by multiple positive cases concurrently. On these occasions, contact tracing teams will work from a single record relating to that contact and mark the additional records as resolved.
Positive cases and close contacts
From the time positive cases were referred to the contact tracing system, the percentage of close contacts reached within 24 or 48 hours excludes a small number of close contacts that could not be linked back to the positive case that identified them. Most commonly this occurs for close contacts who have been identified through the NHS App, or those who have been identified by a positive case residing in one of the other nations.
Demand
Throughout the pandemic, there is a correspondence between the overall burden on the contact tracing system and the time taken to reach close contacts. Significant Increases in cases and contacts correspond to reductions in the proportion reached within 24 and 48 hours.
Household contacts
When a positive case is reached and asked to provide details of their close contacts they are also asked to define the type of contact. Household contacts are contacts that are living or spending significant time in the same household, for example those that live and sleep in the same home, a house of multiple occupancy (HMO) where a kitchen and/or bathroom is shared, students in university accommodation that share a kitchen, and sexual partners, and people who have cleaned a household where a case lives without personal protective equipment.
Measuring the data
This data is management information provided to the Welsh Government by Digital Health and Care Wales. We are publishing this to provide a weekly summary of contact tracing activity in Wales during the coronavirus (COVID-19) pandemic. This data has not undergone the same level of quality assurance as official statistics and the data may be subject to future revisions.
Data included in this release was extracted from the contact tracing system at 12:12 on 15 March 2022. This extract was taken 3 days after the end of the reporting period in order to capture follow-up activity relating to cases referred towards the end of the reporting period.
Data presented in this bulletin is weekly (00:00 Saturday to 23:59 Friday).
Strengths and limitations
Revisions
The number of cases eligible for follow-up for recent weeks may change slightly compared to previous releases due to cases being flagged as not eligible following further investigation by contact tracing teams. More details on this process can be found in the quality and methodology information section.
Daily volatility
Daily data would show large variation between days reflects difference in demand on the system (for example the number of tests performed) with some days seeing more cases feeding through to contact tracing teams. A peak in positive cases or close contacts can occur as a result of:
- a backlog of cases from previous days
- a large batch of test results being submitted
- a new testing site opening
- more testing capacity becoming available
Daily data is available on StatsWales.
Comparability
The number of cases referred for contact tracing is different to the number of new cases published by Public Health Wales. These sources of data are not directly comparable due to differences in timing and the level of validation carried out, as cases submitted to the contact tracing system need to be handled manually by contact tracing teams.
Related links
Contact tracing is an important part of the Welsh Government’s Test, Trace, Protect strategy. The strategy is being delivered through the NHS Wales Test, Trace, Protect service.
What you should do if you have COVID-19 symptoms, have tested positive for COVID-19, or have been in contact with somebody who has COVID-19.
What data is available about how the NHS COVID-19 app is being used? (NHS)
Data for contact tracing via the NHS COVID-19 App is published by The Department of Health and Social Care and includes data on users who have completed the symptom checker, test results received, users notified to self-isolate and check in events that have taken place. Latest published data and more information on this can be found at:
Weekly statistics for NHS Test and Trace (England) (UK Health Security Agency)
Experimental statistics on NHS Test and Trace since its launch on 28 May 2020. Includes reports on NHS Test and Trace (people tested and contact tracing) and rapid (lateral flow device) testing for people without symptoms.
Quality and methodology information
National Statistics status
These statistics are not National Statistics. However, as far as has been practicable, they have been collected and validated in accordance with the pillars and principles within the Code of Practice for Statistics. We continue to develop the data collection and quality assurance process to improve the data.
These statistics have been produced quickly in response to developing world events.
Well-being of Future Generations Act
The Well-being of Future Generations Act 2015 is about improving the social, economic, environmental and cultural wellbeing of Wales. The Act puts in place seven wellbeing goals for Wales. These are for a more equal, prosperous, resilient, healthier and globally responsible Wales, with cohesive communities and a vibrant culture and thriving Welsh language. Under section (10)(1) of the Act, the Welsh Ministers must (a) publish indicators (“national indicators”) that must be applied for the purpose of measuring progress towards the achievement of the wellbeing goals, and (b) lay a copy of the national indicators before Senedd Cymru. Under section 10(8) of the Well-being of Future Generations Act, where the Welsh Ministers revise the national indicators, they must as soon as reasonably practicable (a) publish the indicators as revised and (b) lay a copy of them before the Senedd. These national indicators were laid before the Senedd in 2021. The indicators laid on 14 December 2021 replace the set laid on 16 March 2016.
Information on the indicators, along with narratives for each of the well-being goals and associated technical information is available in the Well-being of Wales report.
Further information on the Well-being of Future Generations (Wales) Act 2015.
The statistics included in this release could also provide supporting narrative to the national indicators and be used by public services boards in relation to their local wellbeing assessments and local wellbeing plans.
Further information
For information and advice on contact tracing please refer to our Test, trace, protect: coronavirus guidance page.
Next update
Thursday 24 March 2022
We want your feedback
We are considering reducing the frequency of some of the COVID-19 related statistical releases, including this publication. We welcome any comments or feedback on how you use these releases, and any changes to them via kas.covid19@gov.wales.
Contact details
For queries about the data
Statistician: Ryan Pike
Telephone: 0300 025 6415
Email: kas.covid19@gov.wales
Media: 0300 025 8099
SFR 86/2022