Open letter to Gavin Williamson asking that daily contact testing trials in schools be suspended immediately due to ethical concerns. A letter that has broad support from many organisations, parents, MPs and many others.

First published in June 2021.

Dear Gavin Williamson
Secretary of State for Education
Department for Education,

We are writing to express our concerns about certain aspects of the trials on the use of daily contact testing in schools. [1] These have become even greater in the light of two developments, the dominance of the delta (B.1.617.2) variant of SARS-CoV-2 and recall of the INNOVA LFD test following investigations by the US Food and Drug Administration (FDA). [2,3]

Like you, we see the harms arising when children miss school, worsening existing inequities. This is why we have called repeatedly for mitigations in schools and for keeping community transmission low, to reduce the impact of covid-19 on children, families, and the wider community. [4] We also understand the need for high quality clinical trials to develop evidence-based policy to support children, families, and schools. However, we are sure you will agree that these trials should be firmly grounded in the principles of Good Clinical Practice (GCP), as outlined in the Declaration of Helsinki. [5]

Ethical and scientific concerns with daily contact testing trials

To recall, the GCP principles require that trials should be scientifically sound. [6] The available data on any investigational product used should be adequate to support the trial. The trial should be conducted in line with regulatory requirements including registration of the study protocols prior to the start date, and approved by an independent ethics committee. The anticipated benefits of taking part in the trial must outweigh the risks, and informed consent must be sought from all those participating in the trial. The daily contact testing trials fail to meet several of these requirements.

Conditions of equipoise unlikely to be met

We welcome the principle of conducting research to reduce school absences associated with covid-19 and understand the appeal of a study evaluating the effectiveness of regular Lateral Flow Device (LFD) testing in schools as an alternative to 10-day isolation for contacts of cases. [7] However, ethical trials require the condition of equipoise—i.e. when there is sufficient grounds to think that the intervention may be as good as standard practice or the control intervention. If the standard practice is known to be better, then we do not have equipoise. In this case, equipoise is unlikely to be met. Mathematical modelling shows that when contact tracing in schools is conducted rapidly (within three days), as is often the case in schools, and with equal adherence to these measures, daily contact testing always leads to more transmission compared with isolation. [8] While we acknowledge that daily contact testing of contacts may reduce transmission by additionally acting as a trigger for household contacts to quarantine, this, if anything, highlights the flaws of the current policy that only requires the contact and not the household to isolate. Mathematical modelling suggests that the most effective strategy would be one of daily contact testing and isolation, rather than daily contact testing alone. [8]

Concerns about risks due to missed infections by LFD tests in these trials

It is undisputed that LFD tests cannot detect the lower levels of virus among individuals in early infection. [9,10] Data from Liverpool showed that one third of cases with high viral loads were missed by the LFD where testing was carried out by non-experts. [9] Despite claims that LFDs may pick up “infectiousness” with high accuracy even if they don’t pick up “infection,” there are no systematic data that currently support this claim for asymptomatic testing by non-experts. Studies that have examined this have only focused on transmission from symptomatic cases, and assumed high test accuracy based on testing by laboratory scientists or health-care workers, which do not apply here. [10-11] Data from contacts in the Test-and-Trace programme have shown that spread can occur from individuals who had low viral loads at the point of testing. [10] Thus there is a high chance that infected contacts in a classroom may be infectious before they are detected as positive by a LFD test. This trial is gambling on the undetected infectious period in infected contacts being short enough for disease spread not to occur, despite the evidence showing little support for this.

Lack of authorisation of tests for “green light” testing

In line with this, the Medicines and Healthcare products Regulatory Agency (MHRA) and the Centers for Disease Control and Prevention (CDC), have both recommended that isolation should continue among contacts, even with negative tests, and MHRA authorisation does not extend to the use of these as “green light tests,” where negative tests would permit certain activities. [12,13] The recent withdrawal of the INNOVA LFD test by the FDA, citing “risk to health,” including risk of “serious illness and death,” and “further spread of the SARS-CoV-2 virus” is all the more concerning. [3] The Orient Gene tests being used in these trials have limited data on accuracy and have not been tested among children, asymptomatic people, and accuracy of testing by non-experts is unknown. [11] This test is not currently registered with the MHRA.

The weakness of the scientific justification exacerbates the already considerable ethical concerns with these trials. There is little transparency around the study protocols and ethical approvals. Even the Participant Information Sheet (PIS) provides no information about ethical approvals for the study. [14] Freedom of Information requests have revealed that ethical approval was provided by the Public Health England (PHE) Research Ethics and Governance of Public Health Practice Group (REGG), which specifically regulates research conducted by PHE. The trial was only registered publicly after recruitment had begun and to our knowledge, there is no stated provision for safety monitoring and what would happen should there be any significant safety concerns. [7] This is all the more important given the risk posed by these trials is amplified by the lack of basic mitigations that are known to be effective in reducing transmission in schools. [4,15,16]

Lack of consideration and communication of possible harms

Moreover, although individual informed consent may be challenging to obtain in cluster trials, there do not seem to have been efforts made to obtain consent from stakeholders at community level either. Only a limited set of stakeholders have been consulted and even these have not been fully informed of risks. Consent is only being obtained from the parents or carers of children whom the Department of Education deem to be “close contacts.” This is based on a definition based on duration of close physical proximity and does not take into account the airborne transmission of SARS-CoV-2, which means that everyone in the room is at risk. Only those in close proximity to the infected person are being asked for consent; everyone else has no choice but to face the increased risk of infection. Many parents have had to make difficult decisions about whether or not to withdraw their children from in-person schooling. Even those who have consented have not been informed about the risk to themselves and their families. [13] There has been little consideration of potential risks for clinically vulnerable children, staff, and household members. While the PIS states that “there may still be some individuals who have the virus and are not detected by the test,” there is no mention of the risks of long covid and severe illness to children and their caregivers, or of liability insurance for participants who become severely unwell, develop long covid or die during participation in the trial. [14] It was only through FOI requests that we learnt that the Department of Education did not consider it necessary to make indemnity arrangements for the asymptomatic testing programme in education settings.

Concerns about validity of results

We are concerned that these trials do not adequately assess the outcome of increased transmission within schools that may result from replacing isolation with daily contact testing. These trials only carry out two PCR tests on “close contacts” along with LFDs, not testing the whole bubble, or asymptomatic household contacts of those participating which means that the trials may not adequately detect the impact of those with false negative LFDs remaining in classrooms, given that infection in children is often asymptomatic, and can spread silently. With low uptake of LFDs among school children at the moment, it is likely that increased transmission as a result of the intervention will be missed.

Additional risks posed by the spread of the delta variant and lack of robust mitigations in schools

The lack of evidence-based mitigations in schools and the recent removal of the secondary school mask mandate on the 17 May 2021, mean that children, staff, and families have already been put at risk. Proceeding with daily contact testing trials before basic public health measures have been put in place is unconscionable. When the original trials were launched, parents were informed that the trials would not include contacts of cases infected with variants of concern, given the higher risks this would entail. [1] Since then, the delta variant has emerged and become dominant. This variant is 40-70% more transmissible and more severe, approximately doubling the risk of hospitalisation. [2] It shows significant escape from vaccines. [17,18] It has spread rapidly in schools (217 outbreaks as of the 6 June) and led to secondary school age children having the highest infection rates of all age groups. [2,19,20] This has also caused significant educational disruption, with 1 in 3 children not attending school in Bolton recently. [21] Reports from Singapore and China suggest this variant is likely to affect children more than previous variants, and be more severe. [22,23]

Despite this, daily contact testing trials are now being extended to cases of the delta variant. The emergence of this variant, and increased risk to children, staff, and families, requires a review of the ethical issues and risks associated with this trial.

In light of the above, we ask the Department of Health and Social Care (DHSC) to suspend these trials immediately, pending adoption of comprehensive mitigations and to allow time to prepare and provide vital clarity to students, families, teachers, the wider public and the scientific community about the scientific justification and ethical considerations for these trials. We would be very concerned about results from these trials being used as the basis for any public health policy, given the assessment of risk of increased transmission arising from these trials is inadequate. All results from the trial to date should be made public to allow expert peer review.

Finally, given the concerns about the delta variant and surging case numbers it is vital that we take the safest approach possible with children and schools and we refer you to our previous letter of the 4 May 2021 about the need for mitigations (masks, ventilation, smaller bubbles, outdoor learning) in schools. [24] It is deeply concerning that the daily contact testing trials are being presented as a solution for educational disruption when so little has been done in the way of basic and highly effective mitigations that would help reduce educational disruption, and investment in catch-up learning to address inequities created by this. Keeping potentially infected and infectious children and staff in school may make attendance numbers look better for the short term, but the risks and potential consequences are very serious.

  • Deepti Gurdasani, Queen Mary University of London, UK
  • Hisham Ziauddeen, University of Cambridge, UK
  • Trisha Greenhalgh, University of Oxford, UK
  • Alice Roberts, University of Birmingham, UK; Independent SAGE, UK
  • Kit Yates, University of Bath, UK; Independent SAGE, UK
  • Zubaida Haque, Independent SAGE member
  • Susan Michie, University College London; Independent SAGE, UK
  • Martin McKee, London School of Hygiene and Tropical Medicine, UK; Independent SAGE, UK
  • Christina Pagel, University College London,, UK; Independent SAGE, UK
  • Zoë Hyde, University of Western Australia, Australia
  • Diego G. Bassani, University of Toronto, Canada
  • Robert West, University College London, UK
  • Stephen Reicher, University of St. Andrews, UK; Independent SAGE, UK
  • Jon Deeks, University of Birmingham, UK

Competing interests: none declared

On behalf of full list of co-signatories listed at the end of this letter.


  1. Haque DZ.  2021.
  2. Public Health England. SARS-CoV-2 variants of concern and variants under investigation in England: Technical briefing 15, 2021.
  3. US Food and Drug Administration. Stop Using Innova SARS-CoV-2 Antigen Rapid Qualitative Test: FDA Safety Communication, 2021.
  4. Gurdasani D, Alwan NA, Greenhalgh T, et al. School reopening without robust COVID-19 mitigation risks accelerating the pandemic. Lancet 2021; 397(10280): 1177-8.
  5. World Medical Association. WMA Declaration of Helsinki- Ethical Principles for Medical Research involving Human Subjects, 2018.
  6. World Health Organization. Handbook for Good Clinical Research Practice (GCP): Guidance for implementation.
  7. ISRCTN registry. Daily contact testing schools and colleges trial. 2021.
  8. SPI-M-O. SPI-M-O: Statement on daily contact testing, 2021.
  9. University of Liverpool. Liverpool Covid-19 Community Testing Pilot: Interim Evaluation Report, 23 December 2020
  10. Lee LYW, Rozmanowski S, Pang M, et al. SARS-CoV-2 infectivity by viral load, S gene variants and demographic factors and the utility of lateral flow devices to prevent transmission. Clin Infect Dis 2021.
  11. Peto T. COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing. EClinicalMedicine 2021: 100924.
  12. Halliday J. Schools demand No 10 explain unauthorised use of rapid Covid tests. The Guardian. 2021.
  13. Centers for Disease Control and Prevention. Interim Guidance for Antigen Testing for SARS-CoV-2. May 13 2021.
  14. Academy H. COVID Study Trial – Daily Contact Testing (DCT) April 2021. 2021.
  15. Centers for Disease Control and Prevention. Mask Use and Ventilation Improvements to Reduce COVID-19 Incidence in Elementary Schools — Georgia, November 16–December 11, 2020. MMWR 2021.
  16. Lessler J, Grabowski MK, Grantz KH, et al. Household COVID-19 risk and in-person schooling. Science 2021; 372(6546): 1092-7.
  17. Bernal JL, Andrews N, Gower C, Gallagher E, Simmons R, Thelwall S, Tessier E, Groves N, et al. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. MedRxiv 2021.
  18. Wall EC, Wu M, Harvey R, et al. Neutralising antibody activity against SARS-CoV-2 VOCs B.1.617.2 and B.1.351 by BNT162b2 vaccination. Lancet 2021.
  19. Public Health England. Weekly national Influenza and COVID-19 surveillance report: Week 23 report (up to week 22 data) 10 June 2021, 2021.
  20. Office for National Statistics. Coronavirus (COVID-19) Infection Survey, UK: 11 June 2021, 2021.
  21. Weal S, Adams R. Unions call for return of masks to secondary classrooms in England. The Guardian. 2021.
  22. Singapore warns children are susceptible to new strains of coronavirus as schools prepare to shut. ABC News. 2021.
  23. Bradsher K. Delta Variant Producing More Severe Illness, Doctors in China Say. The New York Times. 2021.
  24. Open letter to Secretary of State for Education regarding the need to continue wearing face coverings as a mitigatory measure against SARS-CoV-2 in schools. 2021.

Full list of co-signatories:

Scientists and healthcare professionals
  • Dr. Deepti Gurdasani, Queen Mary University of London, UK
  • Dr. Hisham Ziauddeen, University of Cambridge, UK
  • Prof. Trisha Greenhalgh, University of Oxford, UK
  • Prof. Alice Roberts, University of Birmingham, UK; Independent SAGE, UK
  • Dr. Kit Yates, University of Bath, UK; Independent SAGE, UK
  • Dr. Zubaida Haque, Independent SAGE member
  • Prof. Susan Michie, University College London; Independent SAGE, UK
  • Prof. Martin McKee, London School of Hygiene and Tropical Medicine, UK; Independent SAGE, UK
  • Prof. Christina Pagel, University College London,, UK; Independent SAGE, UK
  • Dr. Zoë Hyde, University of Western Australia, Australia
  • Dr. Noor Bari, Western Sydney Local Health District, Australia
  • Dr. Diego G. Bassani, University of Toronto, Canada
  • Dr. Matt Prescott, Independent scientist, UK
  • Prof. Robert West, University College London, UK
  • Dr. Sakkaf Ahmed Aftab, Chair BMA Yorkshire Consultant Committee, UK
  • Dr. Joe Pajak, FRSC, NHS Foundation Trust Governor, UK
  • Prof. Stephen Reicher, University of St. Andrews, UK; Independent SAGE, UK
  • Ms. Michelle Wong,  Speech & Language Therapist, UK
  • Dr Eilir Hughes, Fresh Air Wales, UK
  • Prof. Jon Deeks, University of Birmingham, UK
  • Dr Alison George, GP and honorary GP in Emergency Medicine, UK
  • Dr Lindsay Fraser-Moodie, GP Registrar & Fresh Air NHS
  • Prof Jacqui Hamilton, Professor of Atmospheric Chemistry, University of York
  • SafeEdForAll, UK
  • Parents United, UK
  • Hazards Campaign, UK
  • One voice: supporting vulnerable adults and children during Covid
  • LongCovidKids, UK
  • Fresh Air Wales, UK
  • Zero COVID Alliance
  • The Citizens, UK
  • Fresh Air Schools Campaign
  • Diane Abbott, MP
  • Caroline Lucas, MP
  • Councillor Jumbo Chan, Brent
  • Claire Cozler, parent, former teacher and Councillor
  • Doreen Geoghegan, Chartered Safety practitioner IOSH Occupational Hygiene Health & Safety
  • Cllr Oliver Patrick, South Somerset District Council
  • Parish Councillor Matthew Doyle
  • Lisa Diaz, Parent.
  • Pablo Diaz, Parent.
  • Pat Bentley, Grandparent.
  • Peter, Grandparent.
  • Martin Corless, Parent
  • Morgane Cozler, student
  • Adam Hamdy, Author and parent
  • Sarah Saul, parent
  • Martin Powell-Davies, candidate for NEU Deputy General Secretary
  • A L Stevens, Parent
  • Amrit Lohia, student
  • Daniella Modos, Parent
  • Andrea Upton, Parent
  • Kim Wareham, Parent
  • James Wareham, Parent
  • Susan Foster, Parent
  • Hilda Palmer, Hazards Campaign, UK
  • James Graham, Parent
  • Georgina Fellows, Parent
  • Damien Willey, Presenter & Parent
  • Sammie McFarland, CEO, LongCovidKids and Parent
  • Frances Simpson MSc FHEA, Co-founder of LCK and Parent
  • Nathalie Pearson BSc (Hons) Ops Manager LCK & Parent
  • Chris Sewell , Parent/Carer
  • Gemma Sewell, Parent, Carer
  • Dave Lawrence BSc Post Qualifying Child Care Studies, Dip SW, C.Q.S.W Parent/Carer
  • Miss Hardy, Parent/Carer
  • Christina Janusz, Parent/Carer
  • Russell Flint, Parent/Carer
  • Kayley West, Parent/Carer
  • Michelle Kenwright, Parent/Carer
  • Sarah Jade, Education Worker
  • Caroline O’Dwyer, Parent/Carer
  • Steve Brindle, Grandparent
  • Stacey McCann, Parent/Carer
  • Yusif Patel, Parent/Carer
  • Kate Gill, Parent/Carer
  • Danny Leech, Parent/Carer
  • Chantelle Marie, Parent/Carer
  • Susan Duell, Parent/Carer
  • Hannah Lakeland, Parent/Carer
  • Sophie Brindle, Education Worker
  • Danielle Bleasedale, Education Worker
  • Sarah Finnerty, Parent/Carer
  • Tara Timms, Parent/Carer
  • T Timms, Education Worker
  • Lisa Williams, Education Worker
  • Jill Richardson, Parent/Carer
  • Natalie Darby, Parent/Carer
  • Steve McCann, Parent/Carer
  • Mrs Milroy, Grandparent
  • Rebecca Hopkina, Parent/Carer
  • Maxine Lingard, Parent/Carer
  • Emma B, Education Worker
  • Jacqueline Everard, Parent/Carer
  • Jennifer Chileshe, Parent/Carer
  • C Thomas-Jones, Parent/Carer
  • Michelle, Parent/Carer
  • Carole, Grandparent
  • John A, Grandparent
  • Charlotte, Education Worker
  • Michelle, Education Worker
  • Dave, Education Worker
  • Sue, Education Worker
  • Samantha Towler, Parent/Carer
  • Katherine Knights, Parent/Carer
  • Richard Knights, Parent/Carer
  • Louise Richards, Parent/Carer
  • Terry Boyce, Parent/Carer
  • Karen Cudmore, Parent/Carer
  • T Mansell, Parent/Carer
  • M Oak, Parent/Carer
  • Mrs Kay Watt MA (Cantab) PGCE, Education Worker
  • Alison Price, Parent/Carer
  • Linda Richards, Parent/Carer
  • Alex Loftus, Parent/Carer
  • Nicola Linbourn, Grandparent
  • Raquel Roberts, Parent/Carer
  • Sam Groves, Parent/Carer
  • Rob Groves, Parent/Carer
  • Hazel Collins, Parent/Carer
  • Lisa Cluett, Parent/Carer
  • Matthew Cluett, Parent/Carer
  • Helen K, Parent/Carer
  • Stephen J, Parent/Carer
  • M Jones, Parent/Carer
  • F Jones, Parent/Carer
  • Kate Bentley, Parent/Carer
  • Paula Buckley, Parent/Carer
  • Mark Storey, Parent/Carer
  • Samantha Weaver, Parent/Carer
  • Stacey Button, Parent/Carer
  • Bethan Desai, Parent/Carer
  • Kaushal Desai, Parent/Carer
  • Christine Green, Grandparent
  • R Smart Parent/Carer
  • Joanna Robinson, Parent/Carer
  • Nicola Grundy, Parent/Carer
  • Julie Cullane, Parent/Carer
  • M.Williams, Parent/Carer
  • Joanna Brady, Parent/Carer
  • Eleanor Hipkiss, Parent/Carer
  • Sharon Woodrow, Parent/Carer
  • Emma Sullivan, Parent/Carer
  • Veronica Foote Parent/Carer
  • Lucy Laine, Education Worker
  • Warren McGill, Parent/Carer
  • Kayleigh Morgans, Parent/Carer
  • Rosie Bainbridge, Parent/Carer
  • Clare Higginson, Parent/Carer
  • Rebecca Mountain, Parent/Carer
  • Miss Sarah Guy, Parent/Carer
  • Audrey A Jones, Parent/Carer
  • Lindsay Reynolds, Parent/Carer
  • Lydia Seal, Parent/Carer
  • Sonia Roczniak-Gulzar, Parent/Carer
  • J Maer, Parent/Carer
  • Nichola Careless, Parent/Carer
  • Donna Mcfaul, Parent/Carer
  • Jean Mcfaul, Grandparent
  • Mr S Ford, Parent/Carer
  • Mrs J Ford, Parent/Carer
  • Samantha Lou, Parent/Carer
  • Martin Redfern, Parent/Carer
  • Jo Smith, Parent/Carer
  • Philip Smith, Grandparent
  • Sam Smith, Parent/Carer
  • Kylie Jensen-Smith, Parent/Carer
  • T Calvert, Parent/Carer
  • Lesley McGlasson, Grandparent
  • Graeme McGlasson, Grandparent
  • Carol Bray, Grandparent
  • Mrs L. Nicholls, Parent/Carer
  • Amanda J, Parent/Carer
  • Pammy, Parent/Carer
  • Kiri Smith, Parent/Carer
  • Claire, Parent/Carer
  • Samantha, Parent/Carer
  • Kerstin Ward, Parent/Carer
  • Donna Rice, Parent/Carer
  • Mike Buckley, Journalist and campaigner
  • Debbie Razey, Parent/Carer
  • David Razey, Parent/Carer
  • Hannah Awesome, Parent
  • Dr Ben King, Teacher and Parent
  • J claydon, Parent/Carer
  • Mrs T Anchors, Parent/Carer
  • Mrs A Yates, Parent/Carer
  • Laura Marsden, Parent/Carer
  • M Jin, Parent/Carer
  • Sylvia Marsden, Grandparent
  • Peter Marsden, Grandparent
  • Candice Glenday, Parent/Carer
  • Janice Roberts, Parent/Carer
  • A Tuff, Parent/Carer
  • V Bailey, Parent/Carer
  • D Bailey, Parent/Carer
  • Kelly Kerr, Parent/Carer
  • Elizabeth Hipkiss, Parent/Carer
  • Abby Brigden, Parent/Carer
  • N Sinclair, Parent/Carer
  • Sara Hudak, Parent/Carer
  • Heather O’Reilly, Parent/Carer
  • Rachel Noble, Parent/Carer
  • John Noble, Parent/Carer
  • Janice Benn, Grandparent
  • William Lam, Parent/Carer
  • Elizabeth Bates, Parent/Carer
  • Tsai, Parent/Carer
  • Deborah Dominey, Parent/Carer
  • Simon Dominey, Parent/Carer
  • C Maidment, Education Worker
  • Mrs Morfitt, Parent/Carer


Dr Deepti Gurdasani, Senior Lecturer in Epidemiology, Statistical Genetics, Machine Learning, Queen Mary University of London.


[This piece was originally published in the bmj and re-published in PMP Magazine on 17 June 2021, with the author’s consent. | The author writes in a personal capacity.]

(Cover: Flickr/Number 10. - Education Sec. Gavin Williamson. | 21 May 2021. / Licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.)

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