Official Statistics section webinar report: Statistical methods for Covid-19: Test, Trace and Protect

On 28 January 2021, 12-1pm, the RSS Official Statistics Section and Health Statistics User Group (HSUG) organised the third in a series of webinars on topics relating to collecting and reporting statistics for Covid-19. The focus of these webinars is on sharing experiences and discussing approaches to the methods being used in the UK to produce the statistics for each of these topics. The topic for this webinar was Statistical methods for Test, Trace and Protect.

The intended audience was people whose work involves producing and/or using data/statistics/information relating to Covid-19. The webinars are not intended for the general public. However, many of the people in the audience will be involved in making information available to the general public and so the webinars will indirectly affect the public.

The aims for the webinar were to provide an opportunity for:
  1. People involved in producing statistics relating to Covid-19 to share their experiences and exchange ideas (note: 'involved in' covers all aspects of production – data collecting, analysis, modelling, interpretation, presentation etc).
  2. People using the statistics to pose questions and make comments.  This will help with their understanding and use of these statistics.
  3. Members of the audience to contribute insights to the analysis and interpretation based on work they are doing.
  4. People producing the statistics to gain an understanding of the queries and comments that users have regarding their statistics, which will be helpful in improving the explanations that are provided with the statistics.
Alison Macfarlane, chair of the RSS Official Statistics Section, welcomed everyone and thanked the speakers and organisers before handing over to Deana Leadbeter, chair of HSUG, who outlined the proceedings as follows: 
  • Participants were muted, but were given the opportunity to provide questions and comments via the ‘chat’ facility where speakers would have a chance to respond. As time was short, fuller responses would be provided afterwards. These are now posted on the HSUG and RSS websites.
  • The meeting was oversubscribed, so a recording was made available for those unable to join. In view of the rapid changes in this area, the recording was only available for two weeks following the meeting.

Webinar Presentations 
NB: Slides for all presentations are available to view.

Sarah Whitehead, Office for Statistics Regulation (OSR) provided an introduction to the OSR, explaining it was the regulatory arm of the UK Statistics Authority with the aim of promoting and safeguarding the production and publication of official UK statistics. It is separate and independent of the Office for National Statistics (ONS).
The OSR appreciates the numerous challenges posed by the pandemic because of the need to develop and publish new information quickly. Some aspects of the figures (test and trace, and vaccinations) are still being developed. OSR guidance was produced at the start of the pandemic (links to this are in the presentation) and it has been a learning process for everyone. Informal pointers show the importance of trustworthiness in the statistical process, in particular by being transparent on plans and the quality of the statistics, and the importance of publishing by default and ensuring the context is explained.
The OSR had been impressed by the working together across the UK to produce nationwide statistics and stressed the importance of collaboration across the countries at the different levels.
Jennifer Snape, of the Department for Health and Social Care, outlined the work on Test and Trace statistics for England which are published weekly on Thursdays at 11am. The timeline from May 2020 was explained with the first publication in June 2020.  There had to be flexibility to adapt to changing priorities and the aim was to start simple with headline data and build in more detail later. A statement of compliance with national statistics was published in June and a UK Statistics Authority Rapid Review was conducted and published in July which gave encouraging feedback on the process.
Following the review the report was restructured to make some aspects clearer and to provide new data. The format established at the end of August is still being used, so has been shown to be robust. In the autumn further data were added and the publication expanded from 10 pages to 40-50. However expansion meant that some data were duplicated in different places so a consolidation of the publication is recently been underway to reduce overlaps.
The plan is to launch a user survey soon to understand who is using it and how, in order to inform the structure into the future. It is also planned to move into new areas including mass testing and local contact tracing.
Over time the main challenges in the work have been achieving the weekly publication cycle and at the same time evolving the programme with a small team (particularly early on). Also the work has been constantly adapting to new aspects such as different tests or ways of getting tests.
Scott Heald, Jade Carruthers and Emma McNair all gave perspectives from Public Health Scotland (PHS).
Scott introduced this session by outlining the creation of Public Health Scotland in April 2020, becoming the focus for publishing a range of health statistics in Scotland. As health is a devolved issue, PHS has a key role in the collection and publication of the public facing Covid-19 statistics and these are produced in daily and weekly publications. High level data are published on the Scottish Government website and more detail is available on the PHS site. In addition, PHS provides a range of adhoc Covid reports on different topics.
Emma outlined the daily dashboard which is published at 2pm each day and showed an example in the slides. Its scope has increased over time and now includes breakdowns by different population groups, local areas and also provides trends over time. There is also open data that allows users to download the information to produce their own analyses. Geographic levels have been an issue as it is important to provide information that is robust but can also be analysed at local levels. The dashboard is evolving and it is hoped to add vaccination data to it soon. It is also very popular with a wide range of users who provide feedback resulting in tweaks to improve the site.
Jade outlined the weekly report which is produced at noon every Wednesday with summary data and infographics. It runs to 20-30 pages with all the week’s detail and also has an open data facility for users to do further analysis. The open data is very popular and a lot of feedback is provided. An example of a contact tracing cluster analysis was also shown illustrating how to monitor the spread of the virus.
The final slide sets out links to the main data sources described and the team would always welcome feedback.
Alexandra Fitzpatrick of the Welsh Government's Knowledge and Analytical Services (KAS) explained how it is responsible for a wide range of statistics including NHS activity, PPE, care homes outbreaks and testing and contract tracing. The rest of the presentation concentrated on contact Tracing. The process of contact tracing through local teams was explained via flow diagrams. The local teams would trace the contacts and give advice and, as they were local, could give more local advice and identify cohorts of interest. The diagrams also showed the work once an index (positive) case had been identified and where data are collected in the system. The flow showed that some follow ups were ineligible (eg in closed settings such as hospitals, care homes) but sorting out some ‘ineligibles’ was a challenge in the work.

The weekly publication was described including contacts and positive cases. Examples were also provided in the slides of the effects of lockdowns and other measures. Analyses included trends in numbers of contacts per case over time: they illustrate the decline in contacts once national and local restrictions are imposed, trends which are not necessarily surprising but provide reassurance.

As well as the weekly data mentioned, the Welsh Government has a daily dashboard containing wider information.

Russell Black from ONS talked about the ONS Covid infection survey. He explained that it started with a pilot of 25,000 people in April, and now covers some 150,000 repeated household visits each fortnight, which include ‘at home’ swab (infection) and venous blood (antibody) collection. It has expanded to the largest social survey outside the census. The work is a result of collaboration between many different organisations.
Russell gave a number of examples of the outputs from the survey include trends in the new variant and breakdowns by occupation eg those in patient facing work. It was also shown how the data could be used to look at the relative growth rates of the different variants. Further information is available on the ONS Insights dashboard and links to this were provided in the final slide.
After the speakers had finished, Deana moved onto general questions and answers. She closed the webinar by thanking all the speakers and participants for their involvement. Further questions could be posted on the webinar address after the meeting and, as this was a fast moving area, there would be discussion on revisiting the topic in a few months.

In addition, if participants have other ideas for topics for Covid-19 webinars then please let the HSUG know at
Author: Richard Willmer, February 2021

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