Peter Roderick: Is it lawful to require self-isolation after a positive covid-19 test? 

In Portugal on 11 November 2020 an appeal court rejected the arguments of the Azores regional health authority that four individuals could be forced to quarantine after one of them had received a positive RT-PCR test for SARS-CoV-2. [1] Citing Jaafar et al. (2020) and Surkova et al. (2020), the court considered the reliability of the test to be “more than debatable” (“mais do que discutível”) and found that the test was not able to determine infection beyond reasonable doubt. [2,3]

In the UK on 11 November 2020 the Department of Health and Social Care was also busy. Its guidance was issued for students in England going home for Christmas between 3-9 December. [4] Offered at least one rapid Innova lateral flow test before they depart, they will commit a criminal offence if they do not self-isolate for 10 days without reasonable excuse if they test positive. [5,6] The preliminary evaluation of the Innova and other lateral flow tests conducted by Public Health England at Porton Down and Oxford University was also press released the same day. [7,8] The government has bought £600m worth of Innova tests. [9,10]   

The reasoning of the Lisbon court raises an important question about the legality of restrictions placed on students and everybody else following a positive lateral flow test, and more widely about the extensive powers of public health, police and immigration officers relating to potentially affected persons under Schedule 21 of the Coronavirus Act 2020. [11]

The main grounds upon which the court ruled the quarantine unlawful were that only registered doctors can prescribe tests and make diagnoses, and that there had been no prior medical observation of the individuals and no intervention of a registered doctor. No such requirements, however, have been applied to the tests being carried out on students, or on others in Liverpool and elsewhere as part of “Operation Moonshot,” or to the requirements that may be mandated under Schedule 21. Neither has the UK National Screening Committee been asked to advise. [12]  

In addition, the accuracy of the Innova test is lower than an RT-PCR test, and “clinical correlation [of positive tests] with patient history and other diagnostic information is necessary to determine infection status.” [5] Jon Deeks, leader of the Cochrane Collaboration’s covid-19 test evaluation activities has said that its “poor detection rate…makes it entirely unsuitable for the government’s claim that it will allow safe ‘test and release’ of people from lockdown and students from university.” [13] The preliminary test evaluation showed high specificity (99.6%), and so a low rate of false positives. [7] Sensitivity, and so the rate of false negatives, was described only as “sufficient” and varied depending on who performed the test—79% if laboratory scientists, 73% if trained healthcare staff, and 58% if self-trained members of the public, and these figures mainly from symptomatic patients. In its press release the government, disgracefully, described the sensitivity rate as “high.” [8] When subsequently used in Liverpool, the test only picked up 5 out of 10 cases detected by PCR test. [14] The sensitivity rate is worrying as regards transmission of the virus, while the false positive rate is worrying if the test is administered to tens of thousands of people in view of the restrictions on the liberty of several hundred that would legally follow.

It is obvious, when reading Schedule 21 that its provisions have been drafted with their significance for personal liberty, and the possibility of courts making a declaration of incompatibility under the Human Rights Act 1998, in mind. The safeguards deemed essential by the Portuguese court are missing, and no advice of screening experts is mentioned. There are though several pre-conditions for the exercise of some of the powers, such as necessity and proportionality, with regard to the person’s wellbeing and personal circumstances, and an appeal to a magistrates’ court against restrictions imposed after assessment. This is not at all obvious when reading the regulations under which students and others could be punished, which were made by the Secretary of State at 5pm on 27 September 2020 and came into force seven hours later, without any parliamentary scrutiny. [6] 

The receptiveness of the Lisbon court to the effects of repressive state power is not surprising in light of Portugal’s brutal regime for much of the 20th century. It’s important not to exaggerate potential effects, but it’s more important not to be complacent, to be vigilant, and to ensure human rights are not violated.  

Peter Roderick is Principal Research Associate, Population Health Sciences Institute, Newcastle University. He is also a barrister.

Competing interests: None declared.


1. Tribunal da Relação de Lisboa, Proc. Nº 1783/20.7T8PDL.L1. 11 November 2020.
2. Jaafar R, Aherfi S, Wurtz N, et al. Correlation Between 3790 Quantitative Polymerase Chain Reaction–Positives Samples and Positive Cell Cultures, Including 1941 Severe Acute Respiratory Syndrome Coronavirus 2 Isolates. Clinical Infectious Diseases, ciaa1491. 28 September 2020.
3. Surkova E, Nikolayevskyy V, Drobniewski F. False-positive COVID-19 results: hidden problems and costs. The Lancet Respiratory Medicine September 29, 2020.
4. Department of Health and Social Care. Christmas guidance set out for university students. Press release. 11 November 2020.
5. Innova Medical Group Inc. SARS-CoV-2 Antigen Rapid Qualitative Test – Instructions for Use. 1 July 2020.
6. The National Archives. The Health Protection (Coronavirus, Restrictions) (Self-Isolation) (England) Regulations 2020.
7. Preliminary report from the Joint PHE Porton Down & University of Oxford SARS-CoV-2 test development and validation cell: rapid evaluation of lateral flow viral antigen detection devices (LFDs) for mass community testing. 8 Nov 2020.
8. Department of Health and Social Care. Oxford University and PHE confirm high-sensitivity of lateral flow tests. Press Release. 11 November 2020.
9. Department of Health and Social Care. SARS-CoV-2 Antigen Rapid Qualitative Test Kits. 26 November 2020.
10. Department of Health and Social Care. SARS-CoV-2 Antigen Rapid Qualitative Test Kits. 2 December 2020.
11. The National Archives. Coronavirus Act 2020, Schedule 21.
12. Raffle A. Screening the healthy population for covid-19 is of unknown value, but is being introduced nationwide. The BMJ Opinion, 9 November 2020.
13. Mahase E. Covid-19: Innova lateral flow test is not fit for “test and release” strategy, say experts. BMJ 2020;371: m4469.
14. Cabinet Office and Department of Health and Social Care. Community testing: a guide for local delivery. Policy Paper. 30 November 2020.