Coronavirus (COVID-19) asymptomatic testing programme: evaluation - November 2020 to June 2021

Introduction

Scotland's Testing Strategy^[1] is a significant part of Scotland's approach to controlling the Covid-19 pandemic. It contributes to minimising virus transmission and supports Scotland in living with the virus in as safe a way as possible. The Testing Strategy sits within Scotland's wider strategic intent for approaching Covid-19. This intent is set out in Scotland's Strategic Framework^[2] (the Framework current during the greater part of this evaluation) and includes the vaccination rollout, non-pharmaceutical interventions, border control measures, self-isolation, and wider supports for the harms caused by the pandemic.

The Testing Programme makes use of asymptomatic and symptomatic testing, using Lateral Flow Devices (LFD) or Polymerase Chain Reaction tests (PCR). LFD tests are intended to be used only for asymptomatic testing, while PCR tests can be used for both a- and symptomatic testing. Regular asymptomatic testing is intended to capture cases of the Covid-19 virus that would otherwise go undetected or be found much later in the virus progression, once symptoms had developed. Testing for and finding asymptomatic cases supports the aim of reducing transmission and saving lives.

The aim has been to encourage the use of this testing in critical frontline infrastructure, such as health and social care, prison and emergency services, and childcare and education settings. Alongside this, community testing has been developed to ensure communities most at risk of Covid-19 outbreaks and/or negative outcomes from Covid-19 have increased access to this testing. Over the time period of this evaluation, a universal offer of asymptomatic testing was rolled out for the wider population (beginning 26^th April 2021).

The overall Testing Programme expanded considerably to take in asymptomatic testing, in a first expansion phase from November, a second phase from January/February, and significantly in April when testing was made available to everyone through the universal offer. Given this expansion and the development of a number of testing pathways to carry out asymptomatic testing, it is important to explore the relevant data and evidence to evaluate this programme of work.

Since March, the Scottish Government has carried out a rolling programme of data analysis and insight to consider the current state of the pandemic and provide insight into the contribution of the asymptomatic testing programme to the strategic intent outlined above. This has been presented weekly to the Testing Programme Board and includes research and evidence from colleagues across Health, Justice, and Education.

This report sets out the evidence and insights we have gathered across the major components of the overall expanded Testing Programme. The pathways examined in this evaluation are the largest testing pathways and/or those examining critical infrastructure: (i) targeted Community Testing; (ii) Early Learning and Childcare (ELC) settings testing; (iii) Health and Social Care Workforce testing; (iv) Police Scotland and Scottish Fire and Rescue Service (SFRS) high risk staff groups; (v) Prison Staff testing; (vi) Schools testing; (vii) Universal testing, with specific research on (viii) the highest risk individuals (previously known as 'shielding') and their households; and (ix) University and College testing.

We recognise that, though the asymptomatic testing pathways may have been set up to provide testing when a- or pre-symptomatic, not every individual will have used them in this way. There is some evidence within this report that people may have been using the tests as a way to 'check' their symptoms when in the early stages. This is an important finding from the evaluation, but we continue to refer to the pathways as 'asymptomatic testing pathways' as this was the intention when setting them up and the expectation of their use, particularly in workplace and critical function settings.

The time period of this evaluation covers the earlier stages of the asymptomatic testing programme – demand has much increased since, as the pathways have established themselves.

Terminology

The Testing Programme: this refers to Scotland's overarching approach to testing, covering all individual testing pathways, and underpinned by Scotland's Testing Strategy.^[3] The Testing Programme includes both symptomatic and asymptomatic testing, but this evaluation focuses on the asymptomatic elements of the programme.

Universal Offer: this refers to the universally accessible offer that gives any individual who does not have Covid-19 symptoms living in Scotland the opportunity to get free lateral flow test kits on a regular basis. The definition 'universal testing' has different meanings in the wider testing literature. For a discussion of those meanings, please refer to Annex B (p. 62).

Testing Pathways: within the overall Testing Programme there is a focus on specific, critical areas where testing has been deemed necessary. These areas are called 'pathways'. Initially asymptomatic testing focused on the critical areas of health and social care, schools, and community testing, before being widened out to capture a number of other critical areas, and finally a population wide offer of asymptomatic testing was developed.

Models of Delivery: this refers to the practical set-up and delivery of each testing pathway. Tests were made available in different ways in each pathway and this context is provided at chapter 4 to better understand the different models, their advantages, and challenges.

Key evaluation questions

This evaluation aimed to answer a set of specific questions relating to the performance and public health impact of the asymptomatic testing programme in Scotland. These come under four headings: the public health impact of testing; attitudes and behaviours; models and delivery; and value for money. The first three areas are addressed in this report and are presented in the order set out below. Analysis of value for money and responses to more detailed modelling questions are being developed by economists in the Scottish Government for future reporting.

The public health impact of asymptomatic (mainly LFD) testing

a) How many positive cases have been identified in total and through which pathways? What is the PCR conversion rate?

b) Has uptake of testing changed over time? Does this differ by pathway and demographic characteristics?

c) What is the profile of those tested and those that test positive in total and for each pathway? Is there is a particular pathway that has a better 'reach'?

Attitudes and behaviours

• Why are people taking up the offer?
• Why are people not taking up the offer, or testing less frequently?
• Which channels are used and do people switch between channels?
• What were people's experiences of navigating the system?
• How do people behave following a positive test result? What does this behaviour vary by and why? What do we know about specific groups?
• How do people behave following a negative test result? What does this behaviour vary by and why? What do we know about specific groups?

Models and delivery

• What have delivery partners learned about the rollout of testing across pathways and how has that changed over time?

Additional evaluation questions to be addressed separately

• Is this a cost-effective intervention?
• Based on modelling, how many hospitalisations and deaths have been avoided?

Sources of data used in the evaluation

All pathways were encouraged to create proportionate evaluation plans depending on requirements from their own Programme Boards (Governance Boards overseeing each pathway). The individual testing pathways have therefore approached their evaluations in different ways, subject also to data availability and time constraints. However, to ensure a level of consistency across all pathways, minimum data requirements were agreed with the overarching Testing Programme Board, for each evaluation to report as far as possible within available data. These are:

• Population size of group tested​
• Uptake of testing and trends in uptake over time ​
• Cumulative total and weekly LFD tests completed​
• % who booked PCR confirmatory test​
• Results of confirmatory PCR test​
• Feedback from workforce and partners

Pathways either used available data or worked to collect new data to respond to these requirements.

One key source of evidence across most pathways is Public Health Scotland's LFD dashboard^[4] and weekly reporting.^[5] The dashboard is made up of data collected from across the testing pathways on tests reported, positive tests, confirmatory PCR tests taken after a positive LFD test, percentage positivity rate, demographic data, and trends over time. Specific use has also been made of the Public Health Scotland Covid-19 Education Surveillance Report.^[6] The data provided on these dashboards relies on test reporting by individuals – individuals provide their test results online or over the telephone. The data collected via these Scotland-specific and UK-level reporting portals is then collected together and analysed by Public Health Scotland (PHS) to provide a picture of the Scottish asymptomatic testing landscape.

Alongside this, analysts worked with other organisations and colleagues across Scotland to collect and make use of their data on uptake and created new programmes of research to deliver other quantitative and qualitative data to provide richer insights on experiences of the different pathways. This included surveys and focus groups. Insights were fed to respective Testing Programme Boards throughout the period of the evaluation to inform decision-making. Please see Annex A for an overview of each pathway. The surveys and focus groups undertaken by most pathways are not made up of representative samples. Those who take part in research are also likely to be more 'engaged populations', again representing a specific section of those taking part in testing. These data caveats are returned to again below and throughout the report so that the results of the evaluation can be better understood and contextualised.

One exception to this is the data used in the Universal Testing pathway. The Universal Testing pathway makes use of regular polling carried out by YouGov for Scottish Government. It is made up of a representative sample of the population made up of around 1000 adults 18+ across Scotland each week. Fieldwork is carried out mainly on the dates shown with the data used (Tuesday-Wednesday in any week), with a small number of interviews carried out on the Thursday morning to supplement this. This representative survey is a reliable and robust method of polling, and was used to better understand the views and behaviour of the Scottish population in relation to the Universal Testing offer. Insights from this polling have also been used to highlight wider thoughts and opinions on asymptomatic testing where relevant throughout.^[7]

In discussing behaviours post-test and examining the process from testing to having to self-isolate, use is made of other Scottish Government work on self-isolation experiences.^[8] As the largest piece of work on a Scotland-specific sample this was deemed the most useful to include in this evaluation. We recognise there is a wider literature on self-isolation and compliance, and have also published a literature review covering some of this wider evidence base.^[9]

Finally, Annex B is an evidence review of evaluation work on testing pilots conducted in the UK, and international scholarly research, aiming to provide an account of models of delivery, benefits, barriers, costs and impacts of asymptomatic testing regimes, and to explore the lessons learned from these experiences. This evidence review will be referenced throughout this evaluation report to make relevant links between Scotland's data and the wider literature.

Data quality and caveats

The quality of data varies by pathway. The majority of data that we use comes from Public Health Scotland via individual reporting mechanisms for each testing pathway. This data does not give a complete picture of the asymptomatic testing programme. Data is not available for everything that we might want to measure and we are often drawing assumptions from incomplete data or data that does not measure exactly what we are assessing. Much of the data is operational and was not created with the intention of using as part of an evaluation. Operational data is updated frequently, but not all pathways update on the same day. We have presented as much data as we have available and many pathways have undertaken empirical research to supplement this, as discussed above. That empirical research is of differing detail and robustness and it is important to stress that, where analysts have undertaken surveys and focus groups (excluding the Scottish Government/YouGov polling data), these samples are not representative of the general population or necessarily of the population within each pathway. Also, those who take part in research are often the most engaged populations and may not be representative of wider experiences and opinions.

It is also worth noting that, while the majority of the testing expansion programme relies on LFD testing, some pathways incorporate PCR tests, such as Prisons and Community Testing (see Annex A). The quantitative data highlighted throughout this report therefore focuses almost exclusively on the use of LFDs – where asymptomatic PCR use is discussed will be made clear.

Demographic data is limited across the datasets, so detailed information on who is testing, where, and when is not available. This means we do not have an adequate understanding of how testing is being used by different groups across Scotland or the reach of particular pathways, both in terms of protected characteristics and socio-economic status.

Finally, the programme itself is complex and rapidly evolving. This report considers data from the pathway evaluations November 2020 up to mid-June 2021, and the picture will have changed in the intervening time to publication. Though an evaluation of this scope is not intended to be replicated going forward, there will be ongoing monitoring of management and operational data to provide insight into the progress and performance of each pathway. This data will help to ensure this rapidly moving picture is fed back as required for decision-making.