I am writing to you on behalf of Zero Covid Scotland, a Scottish campaign for policies that will achieve elimination of community transmission of Covid-19 in Scotland. Zero Covid Scotland is a member of the UK-wide Zero Covid campaign. 
We are deeply concerned to read about plans by the Westminster government to replace self-isolation requirements for contacts of people with Covid-19 infections with daily Lateral Flow Tests.
We would ask you to guarantee that such a policy, which lacks any scientific basis, will not be implemented in Scotland. We would also ask you instead consider whether the 10-day period for self-isolation should be extended in light of evidence that people infected the prevalent Covid variant across the UK (the B.1.1.7 variant first reported in Kent) are infectious for longer than people infected with the original Wuhan strain had been. In February this year, researchers at Harvard University reported: “For individuals infected with B.1.1.7, the mean duration of the proliferation phase was 5.3 days (90% credible interval [2.7, 7.8]), the mean duration of the clearance phase was 8.0 days [6.1, 9.9], and the mean overall duration of infection (proliferation plus clearance) was 13.3 days [10.1, 16.5].“ 
In March this year, the Scottish Chief Medical Officer, Gregor Smith, co-authored an article with Professor Devi Sridhar,  stating: “Governments can be more ambitious, and aim to use vaccines following the measles model – that is, build up population immunity through vaccination and suppress the virus to the lowest possible levels by quickly managing outbreaks as they arise through robust test, trace, isolate and support policies.” We fully agree that this should be the aim of Scottish government policy.
We believe that the current Westminster proposal – which is already being rolled out in large-scale tests in England – risks putting the suppression of the virus out of reach, increasing the risks of further spikes in infections, hospitalisation and deaths, and possibly making another lockdown necessary (particularly if variants which escape any of the vaccines used in Scotland were to spread).
World Health Organisation guidance is that, for individuals with Covid-19 infections and those identified as close contact should be quarantined, 14 days of supported quarantine or self-isolation should be required.  This, too, is the advice of the CDC in USA: “CDC continues to endorse quarantine for 14 days and recognises that any quarantine shorter than 14 days balances reduced burden against a small possibility of spreading the virus. CDC will continue to evaluate new information and update recommendations as needed.”
The UK, including Scotland, already diverges from those public health recommendations by requiring only 10 days of self-isolation. Replacing self-isolation for close contacts with Covid tests would be a further divergence from science-based public health policies. Using Lateral Flow tests would be particularly concerning because of their limited accuracy.
According to a recent article in the British Medical Journal (BMJ): “Although the Medicines and Healthcare Products Regulatory Agency approved the Innova rapid lateral flow test to detect cases of SARS-CoV-2 infection at home, it has emphasised that negative results should not be used as a green light for people to change their behaviour and be less cautious….A recently published Cochrane review found that the tests correctly identified an average of 58% of people who were infected, but the number of samples from asymptomatic people was around a 10th that from symptomatic people in the studies, limiting the conclusions that could be drawn.”
In another BMJ article, three public health experts warned: “Studies have shown that in symptomless people it misses the SARS-CoV-2 virus in a substantial proportion. In the Liverpool pilot study, 60% (95% CI 48% to 71%) of infected symptomless people went undetected, including 33% (19% to 50%) of those with high viral loads who are at highest risk of infecting others.  Among students in Birmingham, only 3% (1% to 16%) of those who would have tested positive on PCR were detected”, adding “Low test accuracy would be less dangerous if people being tested and the public at large received accurate information about the risks and implications of a false negative result”. 
Right now, the Scottish government supports Lateral Flow Tests only for the purpose of identifying people with asymptomatic (and presumably presymptomatic) Covid-19 infections who would not otherwise be tested, stating: “The expansion is aimed at finding cases that would otherwise go undetected, so anyone testing positive can self-isolate and avoid transmitting the virus to those around them“.  The aim, therefore, is to ensure that more people who should isolate in order to prevent community transmission, are indeed required to do so.
If Lateral Flow Tests were used to reduce existing public health measures, i.e. self-isolation requirements for close contacts, then this would increase the risk of work colleagues, school staff and pupils, and anybody in other community settings of being exposed to Covid infections. It would undermine work safety and put everybody in the community at greater risk.
We therefore strongly hope that the Scottish Government will refrain from using Lateral Flow Tests as ‘green lighting tests’, for which they have not been authorised by the MHRA, and that policy measures focus on how best to support people with Covid-19 infections and their close contacts to self-isolate.