‘Exit’ from COVID-19 lockdown: Use of testing and contact tracing

The Assembly Research and Information Service (RaISe) has published a number of papers on testing for Sars-CoV-2 tracking and contact tracing, including ‘Testing for Sars-CoV-2 in the UK; and the use of testing and contact tracing in selected countries’ (4 May 2020), its related blog article (7 May 2020) and ‘The use of digital measures to combat COVID-19’ (22 May 2020).

This article stems from RaISe paper ‘‘Exit’ From COVID-19 ‘lockdown’: Health-related issues’ (20 May 2020) and focuses on (and updates) the use of widespread testing and contact tracing as part of the solution to exiting ‘lockdown’.

Introduction

The WHO has consistently called for extensive testing of all suspected cases of the virus so that confirmed cases are isolated and their close contacts rapidly identified. In countries, where community transmission led to outbreaks with near exponential growth (for example in Italy, Spain, UK) ‘lockdowns’ were implemented in order to slow the spread.

Separate roadmaps and actions are now being implemented in Northern Ireland, England, Scotland and Wales to allow a phased transition away from ‘lockdown’, while suppressing transmission of the virus.

Testing and contact tracing measures were first used across the UK in the early ‘contain’ stage of the pandemic and then stopped when the UK Government moved to ‘delay’ phase (12 March 2020). Each jurisdiction has now resumed this on a much larger scale.

The NI Strategy ‘Covid-19 Test, Trace, Protect, Support Strategy’ is designed to identify (through testing) people with COVID-19, tracing people who have been in close contact with them and supporting those people to self-isolate. This strategy runs alongside continued hand and respiratory hygiene and physical distancing.

Diagnostic testing

Diagnostic testing for SARS-CoV-2 has previously been described in a recent RaISe paper but essentially involves molecular diagnosis using ‘real-time RT-PCR (RdRp gene) assay’, with swab samples taken from the nose, throat and deeper respiratory tract.

In NI, eligibility for testing has recently changed and now everyone over five years of age with symptoms of COVID-19 is being encouraged to “book a test without delay” at nhs.uk/coronavirus or by ringing 119. The procedures for getting a test are different depending on whether you are HSC staff, Primary Care staff, an essential worker or general public. In Scotland, the eligibility is the same as in NI. However, in England and Wales anyone who has symptoms of coronavirus can get a test, whatever their age.

The symptoms considered indictive of COVID-19 are a high temperature; or a new, continuous cough; or a loss of or change in sense of smell or taste.

In line with the rest of the UK, testing is also now available to all care home residents and staff across NI, whether or not they show symptoms. The Department has committed to testing all care home residents by the end of June and by 2 June 2020, around 50% of residents and staff had been tested.

Across the UK, testing is prioritised for health workers and other essential workers and their household members who are symptomatic. The PHA state that testing should be done in the first three days of symptoms appearing, although it is considered effective up until day five.

The test procedure is a ‘self-test’ process (individuals take the swabs themselves) for all tests completed through this national testing programme.

In NI, testing for non-HSC essential workers and the general public is conducted in the drive-through national testing centre sites at the SSE centre (Belfast), City of Derry Rugby Club test centre, Craigavon MOT centre and St Angelo Airport, Enniskillen. There is also a mobile testing unit based at the Ulster University, Coleraine, which can be set up in response to local demand. Limited home testing kits are also available.

In NI, by 2 June 2020 there had been 67,506 laboratory completed tests on 53,704 individuals (some have more than one test) and 4,732 of these had been positive. The NI Executive aims to reach 3,500 tests a day. A consortium (‘Queen’s University Belfast’, ‘Ulster University’, the Executive’s ‘Agri-Food and Biosciences Institute’ and pharmaceutical company ‘Almac’) is expected to deliver 1,400 of these tests per day, with testing at HSC Trust laboratories and the national testing centres delivering the remainder.

The UK Government has stated that it has exceeded its target to increase testing to 200,000 a day by the end of May 2020. However, just over 115,000 tests were actually carried out in the 24 hours up to 09:00 BST on 31 May.

In NI, the guidance remains that as soon as an individual experiences symptoms, they should self-isolate for at least 7 days and anyone else in the household should self-isolate for 14 days. The individual with symptoms should order a test immediately. If the test is positive, the person must complete the remainder of their 7-day self-isolation, and have had at least 48 hours without fever. Anyone in the household should complete self-isolation for 14 days from when the individual started having symptoms. If the test is negative, the person and other household members no longer need to isolate.

However, on 3 June, the Health Select Committee in Westminster challenged the head of the ‘Test and Trace’ programme in England, Baroness Dido Harding, over the risks of false negative results i.e. the test shows someone does not have coronavirus when they are actually do. Evidence from the University of Bristol was cited regarding a systematic review of tests showing that between 2% and 29% (in worst case scenario) of positive cases could falsely appear negative. The reasons for this were stated to be the quality of the swab may be poor, the timing of the test is wrong or there were issues with the laboratory processing.

The research from Bristol highlights that a positive test has more weight than a negative test because of the test’s high ‘specificity’ but moderate ‘sensitivity’ and that a single negative test should not be used to rule-out COVID-19 in patients with symptoms strongly suggestive of the illness.

Surveillance

Another aspect to tracking the virus is ‘surveillance testing’. RaISe papers (4 May 2020) and (20 May 2020) highlighted the range of ‘surveillance’ being carried out across the UK and described the largest population-based surveillance study in the UK. The pilot covers 10,000 households in England and it is intended that the study will be extended to include up to 300,000 participants across all four UK nations within the next year.

The most recent results, published on 5 June, indicate that the number of people in England testing positive has decreased in recent weeks and at any given time between 17 May and 30 May 2020 an average of 0.10% of the community population had COVID-19 (around 53,000 people). As of 24 May 2020, 6.78% of 885 individuals tested positive for antibodies to the virus since the start of the study on 26 April 2020.

Contact Tracing across the UK

RaISe paper (4 May 2020) and blog article (7 May 2020) covered what is meant by contact tracing and also described the European Centre for Disease Control and Prevention’s guidance on contact identification and management.

A ‘contact’ is any person who had contact with a COVID-19 case within a timeframe ranging from 48 hours before the onset of symptoms (or in the case of no symptoms 48 hours before the sample which led to confirmation) to 14 days after the onset of symptoms (or the confirmation). The risk of infection depends on the level of exposure.

On 22 April 2020, the UK Secretary of State for Health, Matt Hancock, stated that the UK Government would bring in large-scale contact tracing once the number of new cases fell, involving technology (contact-tracing ‘app’) and contact-tracers (making thousands of calls a day to trace the contacts of those testing positive). ‘NHS test and trace’ was published on 27 May 2020. This approach is likely to become a part of everyday life across the UK until an effective vaccine is developed and a vaccination programme has been delivered.

The PHA in NI re-introduced contact tracing in April 2020 with the ‘COVID-19 Test, Trace, Protect, Support Strategy’. Now anyone who tests positive for coronavirus will be contacted by the Contact Tracing Service and will need to share information about their recent contacts (household members, people with whom they have been in direct contact, or been within two metres for more than 15 minutes). People identified as ‘close contacts’ must stay at home for 14 days, even if they do not have symptoms.

RaISe paper (22 May 2020) covered digital measures, including the contact-tracing ‘app’.  The UK Government ‘app’, having been trialled on the Isle of Wight from 5 May 2020, is expected to be available to the rest of the UK during the month of June.

In NI, the Health Minister, Robin Swann has stated that digital tools will also be developed to complement NI’s telephone-based contact tracing. Scotland’s programme ‘Test and Protect’ (live from 28 May) is relying on contact tracers. The First Minister, Nicola Sturgeon, stated that “at some point in the future” a proximity app may have a role to play. The Welsh Government launched its “test, trace, protect” system on 1 June, using contact tracers, but has plans to use the ‘app’.

Antibody testing

The antibody test to see if someone has previously been infected with SARS-CoV-2 and produced an immune response, has been described in RaISe paper 20 May.

As there is no strong evidence yet showing that those who have produced antibodies are immune, the value of antibody tests appears to be currently limited to knowing whether someone has had the virus or not, and providing research data. The WHO only recommends the use of antibody tests in research settings and highlights that large-scale studies involving tens of thousands of individuals are needed to draw definitive conclusions.

In the UK an antibody test made by Roche was approved by Public Health England in mid-May 2020, shortly followed by one made by Abbott Laboratories. The UK Government then announced the start of a national antibody testing programme to NHS and care staff in England. The UK Government has signed contracts to supply over 10 million antibody tests and each devolved nation will decide how to use its allocation. It also continues to work in partnership with the private sector to develop a ‘finger-prick’ type test for home use.

Other Countries

RaISe paper (4 May 2020), and blog article (7 May 2020) included the success or otherwise of testing, tracking and contact tracing in a range of countries. It is beyond the scope of this article to update that information but since then Turkey has also been highlighted as controlling the virus with robust contact tracing systems.

The system in Turkey grew out of its method used for decades to contain outbreaks of measles and flu. Around 5,800 teams of two/three medical staff (wearing protective equipment) call door to door telling contacts to stay at home for 14 days, even if they do not have symptoms. Other teams then call them daily to ensure compliance and check on their health. If they report symptoms, they get another visit to give a swab sample (taken by the medical staff). A coordination centre oversees the field visits and follow-up calls by telephone.

Challenges

At the start of the outbreak the UK’s limited testing capacity was dwarfed by the number of possible new infections. Throughout April and May 2020, the UK ramped up capacity and only with this increased capacity could all the jurisdictions of the UK recently start to use their testing and contact tracing systems to ease out of ‘lockdown’.

The Scientific Advisory Group for Emergencies (SAGE) have stated that such systems need to reach 80 per cent to be effective. It is believed that out of 4634 contacts notified to NHS Test and Trace in England between 28 and 31 May, only 1749 were contacted (around 38%). It is early days for ‘Test and Trace’ and, as the ‘app’ is not yet rolled-out across England, this is likely hampering efforts.

In terms of the success of testing and contact tracing a number of issues have been identified.

Not everyone who contracts the virus shows symptoms, yet are likely to be spreaders. Researchers at the University of Oxford reviewed 21 published reports and found that there is not yet a ‘single reliable study to determine the number of asymptomatics. It is likely we will only learn the true extent once population based antibody testing is undertaken’.

Their review indicated a very wide percentage range of asymptomatic cases testing positive (5% to 80%).

It has also been stated that the safe isolation of cases is an omission from the test and trace plans, with anecdotal evidence of household transmissions arising from failed isolation in high-density living households, particularly where there is intergenerational living and vulnerable household members.

There has been a focus on the reproduction (R) number of the virus. However, the R number is the average picture. In reality, it seems the spread may be more uneven. Recent research strongly suggests that a small number of so-called ‘superspreading events’ appear to be responsible for the majority of cases. They estimated that 80% of all secondary transmissions were caused by around 10% of infected individuals. It is hoped that such ‘events’ can be controlled with the use of testing and contact tracing.

Dr Muge Cevik, of the University of St Andrews, highlighted that not all activities or all environments have the same risk:

We need to understand the transmission dynamics so we can concentrate our contact-tracing focus….But if we can avoid these superspreading events, and the environments and activities associated with them, you can decrease almost 80% of infections.

Of key concern should also be that research has shown that a single negative test should not be used to rule-out COVID-19 in patients with symptoms strongly suggestive of the illness. There are a number of implications:

False negatives carry substantial risks; patients may be moved into non-COVID-19 wards leading to spread of hospital acquired covid-19 infection, carers could spread infection to vulnerable dependents, and healthcare workers risk spreading covid-19 to multiple vulnerable individuals. Clear evidence-based guidelines on repeat testing are needed, to reduce the risk of false negatives.

Should the UK Government now be advising the public about the known risk of incorrect negative tests and encouraging them to get a second test if they continue to have symptoms? This would also seem naturally to lead to the need for stronger advice to exercise extreme caution regarding continued self-isolation if an individual tests negative but continues to have symptoms.