Briefing on Operation Moonshot screening for SARS-CoV-2.
15 November 2020
Government plans for mass testing for SARS-CoV-2 – sometimes referred to as Operation Moonshot – signal a major change in strategy, away from the current focus on test and trace, which targets people with symptoms and their contacts, to screening the general population who do not have symptoms.
Screening the general population is currently being piloted in Liverpool and a more targeted approach to screening will be applied in universities, towns and cities in the coming month.
The shift to population screening of asymptomatic people raises a number of questions about the likely impact of this new strategy, its cost, the organisational challenges it presents, the performance of the tests that will be used, and the likely effectiveness (or not) of the overall programme. This briefing note outlines some of the key issues at stake. Our goal is to inform journalists and the public and to encourage careful and informed deliberation on the new policy.
- We do not know, based on current evidence, whether screening the general population for SARS-CoV-2 will increase or decrease disease transmission, hospitalisation, and death. Detection and isolation of asymptomatic cases could potentially decrease disease transmission, but false reassurance from missed cases could potentially increase transmission, if people then engage in more risky behaviour.
- The proposals for society-wide screening will cost more than any other healthcare intervention contemplated, and has the potential to cause harm through significant diversion of healthcare resources.
- Population screening for SARS-CoV-2 is not endorsed by WHO or SAGE, and it been developed without input from the UK National Screening Committee, the body responsible for advising ministers on screening strategy.
- The most urgent priority is the UK’s test and trace system, which requires urgent improvement.
- All tests for SARS-CoV-2 are imperfect. Applied in population screening, any of the existing tests would falsely label as positive many people who are not infectious. The new rapid antigen tests – which are key to the Moonshot proposal – also carry the risk of missing many cases.
- Claims that rapid tests are positive when individuals are infectious and negative when they are not are misleading, as it is not possible for screening tests to establish reliably who is and is not infectious.
- New rapid tests for detecting SARS-CoV-2 are important, but their performance for population screening would need to be carefully evaluated in asymptomatic people in field settings ie, not simply in laboratory setting using ideal samples.
- Rapid tests may be valuable for improving the capacity and speed of targeted testing in other settings. The priority should be to evaluate how the tests perform in such settings: testing for contacts of known cases, investigation of clusters and screening people who pose a risk for vulnerable people and settings.
- If testing is centrally run and conducted in parallel to local services without sharing of information and involvement of local organisations, then opportunities for providing effective outbreak control will be lost.
- All research, including pilots, must follow the well-established principles of informed consent that govern medical research.
- Public trust will be undermined if there is a lack of transparency about the procurement process and effective use of competitive tendering to ensure value for money of government contracts.
- Ineffective testing strategies and inaccurate tests endanger public confidence in all SARS-CoV-2 testing.
- Decision-making processes of such cost and magnitude should be transparent, accountable, and evidence-based, and should involve appropriate expertise.
Prof Jon Deeks
Professor of Biostatistics, University of Birmingham
Prof Allyson Pollock
Clinical Professor of Public Health, Newcastle University
Prof Sian Taylor-Phillips
Professor of Population Health, University of Warwick
Dr Angela Raffle
Consultant in Public Health; Honorary Senior Lecturer, University of Bristol