Author: Azeem Majeed

I am Professor of Primary Care and Public Health, and Head of the Department of Primary Care & Public Health at Imperial College London. I am also involved in postgraduate education and training in both general practice and public health, and I am the Course Director of the Imperial College Master of Public Health (MPH) programme.

Reducing the covid-19 isolation period in England: a policy change that needs careful evaluation

How long people with covid-19 should self-isolate depends on the period for which they remain infectious. On 4 January, the US Centers for Disease Control (CDC) updated covid-19 isolation and quarantine recommendations with shorter isolation (for asymptomatic and mildly ill people) and quarantine periods of 5 days to focus on the period when a person is most infectious, followed by continued masking for an additional 5 days.1 This policy was based on a modelling study from the United Kingdom by Bays et al which showed that after the 5th day after a positive test, an estimated 31% of persons remained infectious.2 All the authors of this modelling study, which was published as a pre-print on 24/12/2021, work for UK Health Security Agency (UK HSA).

On 22 December 2021, the UK HSA reduced self-isolation for covid-19 cases in England from 10 to 7 days following negative lateral flow tests on days 6-7. The UK HSA stated that that a 7-day isolation period alongside 2 negative lateral flow tests had nearly the same protective effect as a 10-day isolation period without testing for people with covid-19.

On 1 January, the UK HSA published a blog on using lateral flow tests to reduce the self-isolation period.3 The blog provides background to explain the reasons for the difference between the policies. It also stated that after 10 days self-isolation, 5% of people will still be infectious; and that ending self-isolation after 7 days and two negative lateral flow tests resulted in a similar level of protection.

The two negative test results are essential in safely supporting the end of self-isolation. Without testing, modelling suggests that 16% of people would still be infectious after day 7.  On 13 January, the Health Secretary Sajid Javid stated that from 17 January people will be able leave isolation from the start of day six after two negative lateral flow tests on days 5-6.

Both the US CDC and the UK HSA have based their length of isolation policy mainly on a single modelling study. The data on which the modelling was based It is therefore very important. Bays et al provide a single reference for “infectious period distribution”, a UKHSA modelling paper by Birrell et al published on 31 May 2021.4 Hence, it did not contain any information about the Omicron variant of SARS-CoV-2. It gives as a data source: “the Wuhan outbreak additionally provides information on epidemiological parameters: the duration of infectiousness, the mean time from infection to symptom onset; the probability of dying given infection and the mean time from symptoms onset to death”.

The Wuhan report by Li et al was published in New England Journal of Medicine on 26 March 2020.5 It does not contain any empirical information on the time for which cases were infectious. It only estimates the mean serial interval (MSI), based on six cases only, which represents the average time between the time of symptom onset of a primary case and that of a secondary case.6 The MSI is widely used in infectious disease surveillance and control because it allows investigators to identify epidemiologic links between cases and to diagnose new cases that have such epidemiologic links with laboratory-confirmed cases.  The MSI in Li et al is 7.5±3.4 days (95% CI, 5.3 to 19). There is no information specifically about infectious periods.

Policies in both the UK and US are based on limited data and only on the wild-type SARS-CoV2 variant. Ideally, there should be population-based studies which included daily monitoring of culturable Omicron variant viral shedding (or even better actual transmission, which should be available from large databases) and PCR and lateral flow testing. A 2020 (so pre-Delta) rapid scoping review and analysis from Ireland of available evidence for serial testing asymptomatic and symptomatic cases showed substantial variation in the estimates, and how the infectious period was inferred.7 One study provided an approximate median infectious period for asymptomatic cases of 6.5–9.5 days. Median pre-symptomatic infectious period across studies varied over <1–4 days (and there are several recent studies of the Omicron incubation period showing it is short). Estimated mean time from symptom onset to two negative RT-PCR tests was 13.4 days (95% CI 10.9 to 15.8), but was shorter when studies included children or less severe cases. The only currently available study of the Omicron variant is a small Japanese report which showed the number and percentage of Omicron variant virus isolation positive samples as 7/17 (41.2%) after three to six days and 2/18 (11.1%) at seven to nine days.10

The change in isolation policy for people with covid-19 in England is a pragmatic step that will allow people to return to productive work, education and social activities more quickly. People may also be more likely to comply with a shorter isolation period. But the changes should have been based on careful monitoring and review based on new data on the Omicron variant, not on data on the wild type of SARS-CoV-2. We therefore need careful evaluation of the new shorter isolation period to ensure that people are following the guidance on self-testing and symptoms, and not ending their isolation period too early, and thereby putting others at risk of infection from covid-19.

A version of this article was first published in the British Medical Journal.

DOI: https://doi.org/10.1136/bmj.o184

References

  1. US Centers for Disease Control. What We Know About Quarantine and Isolation: Why CDC Shortened Isolation and Quarantine for the General Population: US Centers for Disease Control, 2022.
  2. Bays D, Whiteley T, Pindar M, et al. Mitigating isolation: The use of rapid antigen testing to reduce the impact of self-isolation periods.medRxiv2021:2021.12.23.21268326. doi: 10.1101/2021.12.23.21268326
  3. UK Health Security Agency. Using lateral flow tests to reduce the self-isolation period: UK Health Security Agency, 2022.
  4. Birrell P, Blake J, van Leeuwen E, et al. Real-time nowcasting and forecasting of COVID-19 dynamics in England: the first wave.Philosophical Transactions of the Royal Society B: Biological Sciences2021;376(1829):20200279. doi: doi:10.1098/rstb.2020.0279
  5. Li Q, Guan X, Wu P, et al. Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus–Infected Pneumonia.New England Journal of Medicine2020;382(13):1199-207. doi: 10.1056/NEJMoa2001316
  6. Vink MA, Bootsma MCJ, Wallinga J. Serial Intervals of Respiratory Infectious Diseases: A Systematic Review and Analysis.American Journal of Epidemiology2014;180(9):865-75. doi: 10.1093/aje/kwu209
  7. Byrne AW, McEvoy D, Collins AB, et al. Inferred duration of infectious period of SARS-CoV-2: rapid scoping review and analysis of available evidence for asymptomatic and symptomatic COVID-19 cases.BMJ Open2020;10(8):e039856. doi: 10.1136/bmjopen-2020-039856
  8. van Kampen JJA, van de Vijver DAMC, Fraaij PLA, et al. Duration and key determinants of infectious virus shedding in hospitalized patients with coronavirus disease-2019 (COVID-19).Nature Communications2021;12(1):267. doi: 10.1038/s41467-020-20568-4
  9. Monel B, Planas D, Grzelak L, et al. Release of infectious virus and cytokines in nasopharyngeal swabs from individuals infected with non-B.1.1.7 or B.1.1.7 SARS-CoV-2 variants.medRxiv2021:2021.05.20.21257393. doi: 10.1101/2021.05.20.21257393
  10. National Institute of Infectious Diseases Disease Control and Prevention Center. Active epidemiological investigation on SARS-CoV-2 infection caused by Omicron variant (Pango lineage B.1.1.529) in Japan: preliminary report on infectious period: National Institute of Infectious Diseases Disease Control and Prevention Center, National Center for Global Health and Medicine, 2022. https://www.niid.go.jp/niid/en/2019-ncov-e/10884-covid19-66-en.html

Why the government’s new policy on face masks in England is a retrograde step

The government announced today that face masks will soon no longer be mandatory in England. Why is this a retrograde step in controlling the spread of Covid-19?

Covid-19 is an infection that is largely spread indoors – particularly in crowded, poorly ventilated areas – through inhaling droplets and aerosols produced by infected people when they cough, sneeze, sing, talk, or breathe. Face masks are a simple method of reducing the risk of infection – but masks work much better if they are worn by large numbers of people. The main function of a mask is to reduce the emission of droplets from infected people into the air. The droplets are captured by the mask and hence less virus enters the air. Much of the benefit of wearing face masks goes to other people but they can also benefit the wearer, particularly if a high-specification FFP2 mask is worn that filters out more particles and droplets when the wearer breathes in air.

Wearing face masks will reduce the spread of the coronavirus and help protect others. This is very important in settings where we are in contact with older and more vulnerable people – such as in supermarkets and on public transport. Wearing a mask has no major side effects, and does not change a person’s oxygen or carbon dioxide levels. Widespread wearing of face masks has been an important part of the pandemic control strategies of countries that have been more successful in containing the spread of Covid-19.

Vaccines are essential and can protect us from developing a more serious illness, as well as reducing the risk of death. But we must maintain the use of other control measures, such as the use of face masks, until we are past the worst of the Covid-19 pandemic.

Isolation for people with Covid-19 in England: Follow the guidance carefully

The UK government has announced that people in England self-isolating because of a Covid-19 infection will be able to end their isolation period after 5 full days instead of the previous 7 days if they test negative on both day 5 and day 6 with a lateral flow test and do not have a temperature. The change comes into force on Monday 17 January 2022. What are the implications of the government’s decision to reduce the isolation period to 5 days for people in England with Covid-19? In summary, it’s a pragmatic step with some benefits but there are also some caveats and concerns that the government needs to address.

A shorter isolation period will allow people to return to work, education and social activities more quickly than the previous 7-day or 10-day isolation periods that we had in England. This will help address workforce shortages in the economy and will also allow children and students to resume their education. A shorter isolation period may also lead to greater compliance, as many people do not comply with longer isolation periods.

But some people will remain infectious after 5 days, so there are risks from this policy. A lateral flow test will identify many of the people who are infectious but some will be missed by the tests. It’s essential therefore that people also focus on their symptoms and not just rely on the results of their lateral flow tests. We need to remember the expression that doctors have: “Treat the patient and not the test result.”

If you remain unwell after 5 days – for example., if you have a high temperature or a bad cough – you should continue to isolate. Although many people of working age will have a mild infection – particularly if fully vaccinated – some people will have a more prolonged illness. The government does not mention cough as one of the symptoms that should lead to a longer isolation period – probably because a cough can persist for some time after a respiratory infection. If you feel well and have a mild cough, that is acceptable. But if you have a severe cough, you should consider extending your isolation period to longer than five days.

People should also not rush back to work and other activities too quickly. Take the time you need to fully recover from your illness before you return to work or education. Everyone is different and we recover at different speeds from an illness. This is irrespective of the results of your lateral flow tests. Base your recovery on how you feel and not just on your test results.

The government’s new policy is largely based on one modelling study which estimated that people with negative lateral flow tests on day 5 & day 6 are as likely to be infectious as people after a 10-day isolation period (7% v. 5% is the government’s estimate). Ideally, we would have stronger evidence from real-world studies about people’s infectivity after different isolation periods (5, 7 & 10 days) and what extra information is obtained about infectivity from lateral flow tests. But this research would take some time to complete and review. The government has therefore taken the decision to act now – but it must assess the impact of its new policy and collect the data needed to do this.

We need careful evaluation of the new shorter isolation period to ensure that people are following the guidance on self-testing and symptoms, and not ending their isolation period too early, and thereby putting others at risk of infection. We also need to consider how the guidance would be applied for people dealing with clinically vulnerable people. This would include guidance for NHS staff, those working in care homes, and people providing social care.

Finally, would you want to share a room with someone who was 5 days past the start of their Covid-19 infection and who was coughing all over you? Follow the guidance, particularly on symptoms, and don’t just rely on the results of the lateral flow tests to predict how infectious you are to avoid placing others at risk of infection.

London is an important barometer for the omicron wave in the United Kingdom

Over the last few weeks, the United Kingdom has experienced a record number of covid-19 infections, driven by the rapid spread of the Omicron coronavirus variant, with the daily reported case numbers approaching 200,000 on some days. This has placed considerable pressure on the NHS through a combination of people seriously ill from covid-19 and staff absences. Other parts of the economy such as public transport have also been badly affected by staff absences.

A sustained period of high infection rates would be very damaging for the UK. But there are now signs that the number of covid-19 cases in London – the first area of the UK to face the wave of infection from Omicron – may have peaked. In which case, a similar pattern of declining case numbers may be seen in other parts of the UK later this month.

There were several factors that drove the early increase in Omicron cases in London. London is the UK’s main international travel hub with the UK’s busiest airports located nearby. Overseas travellers who are infected with a new coronavirus variant are more likely to arrive in the London region than in other parts of the UK. London also has a very large number of international visitors – for activities such as work, study, tourism, leisure, and sports events. London is the also UK’s largest city and is very densely populated, with many overcrowded households, often with people from three or more generations living together, which makes infections more likely to spread, including to clinically vulnerable groups who will be at much greater risk of adverse outcomes such as hospitalisation.

London also has a lower covid-19 vaccination uptake than other parts of the UK. Around 20% of people aged 12 and over in London remain unvaccinated, compared to a national average of about 10%. Although vaccines provide less protection from symptomatic infection with Omicron than from the previously dominant Delta variant, they do still provide good protection from serious illness, particularly in people who have had  their booster vaccination. The lower vaccination rate will lead to infections from Omicron spreading more quickly in areas such as London; as well as increasing the likelihood of severe disease. This would in turn increase hospital admissions from covid-19 and pressures across the NHS in London.

After increasing vary rapidly in London, the Omicron wave now shows signs of abating with the number of covid-19 cases and hospital admission dropping in recent days. We can’t confirm yet that the drop will continue; and nor what the impact will be of schools, universities and workplaces reopening. But if the decline is sustained, other parts of the UK can also expect to see similar falls later this month with case numbers dropping first, followed by a drop in hospital admissions after a lag period. This means that the outcome of the Omicron wave well may be less severe than predicted in the more pessimistic government models, particularly in the areas of the UK with the highest vaccination rates.

However, we can’t yet relax our covid-19 control measures. The number of covid-19 cases in the UK will remain high – compared to previous waves – for some time. The NHS will continue to be under pressure, perhaps for many months, trying to cope with the impact of covid-19 on top of the usual winter pressures that it faces each year whilst also trying to deal with the backlog of work that has built up during the pandemic. The NHS will also continue to be affected by staff shortages due to illness. Although the government may wish to declare “victory” against Omicron and end its Plan B measures later in January, it should refrain from doing so. The public also need to continue to practise good infection control measures, building on the “Three C Approach” to personal safety limit the impact of covid-19.

Measures such as wearing face masks in indoor settings should remain in place, with the government and public health agencies encouraging people to use well-fitting FFP2 masks that provide better protection for the wearer, rather than loosely fitting surgical or cloth masks. More targeted use also needs to be made of publicly-funded lateral-flow tests. Finally, the covid-19 vaccination drive must continue – for those who are currently unvaccinated as well as for those who are now eligible for a booster vaccine. A high uptake of booster vaccines will protect against serious illness and buy time until modified vaccines that target Omicron become available later this year.

In conclusion, the experience of London offers some positive news for the rest of the UK and for the government. But we must remain cautious and continue with our covid-19 control measures until infection rates are substantially lower than they are now. We also need to be fully prepared to deliver another booster vaccination programme later this year, whilst also continuing to target the 10% of people aged 12 in the UK and over who remain unvaccinated.

A version of this article was first published in the British Medical Journal.

It’s time for more targeted use of lateral flow tests for Covid-19

Lateral flow tests for Covid-19 that give a result quickly are a key part of the government’s plans to manage the covid-19 pandemic in England.[1] They are required for key workers such as NHS staff; and for people following guidance from Test and Trace, either because they have a covid-19 infection or have been a close contact of a covid-19 case.  The government also announced recently that other groups of workers in essential industries would be required to carry out regular lateral flow tests.[2] This would be in addition to the tests required by other groups, such as school children.

And yet, despite their potential value, the government has been distributing the tests in a very haphazard fashion; with the outcome that many groups – such as NHS staff – are complaining that they are unable to obtain tests.[3] Meanwhile, other groups of people have been using the tests excessively – including families carrying out daily tests on each family member and in some cases, carrying out multiple tests each day. People have also been using the tests to “monitor” themselves daily after a positive PCR result for covid-19; something that is not currently required except for tests on day 6 and day 7 of the isolation period in fully vaccinated people.

As with any area of healthcare, the NHS in England has a limit on the number of lateral flow tests it can offer. Earlier this month, the government stated it was delivering 300 million tests per month.[4] However, even 300 million tests each month (around 10 million tests per day) is nowhere near enough to offer everyone in England a daily lateral flow test. Hence, an appropriate system is needed for prioritising who should have access to the tests; and how the tests are supplied to these groups. The current system whereby most people obtain their tests from the government’s online ordering system means that the tests may not always be  used appropriately or by the people who have the highest priority for testing.

The NHS already has well-established systems for prioritising access to health services. We saw this, for example, with the Covid-19 vaccination programme when early access to vaccination was based on clinical need and for occupational protection.[5] This meant that the elderly, the clinically vulnerable and those working in healthcare had the earliest access to vaccination. The same process has not happened in prioritising access to lateral flow tests. Given the high cost of supplying tests to England’s population and their limited global availability, as more countries aim to increase their own use of the test in the face of the wave of infection from the SARS-CoV-2 Omicron variant, it’s essential for the government to reconsider its policies on community covid-19 testing.

The government is in part responsible for the increased demand for testing from the public that has led to the current shortage of tests. It has encouraged members of the public to test regularly; for example, before social events such as parties; and before meeting friends and family from outside their immediate household. However, it has not offered clear guidance on how frequently to test. NHS staff, for example, are only advised to test twice weekly; far less than some members of the public are currently doing even though they have no medical or occupational reason to test more frequently.

How can we improve how well lateral flow tests are used? As a first step, the government needs to decide what groups should be prioritised for testing and how frequently they should test. Once the size of these groups and their frequency of testing are known, the government can allocate a large enough sample of tests to meet their needs. Priority groups for access to lateral flow tests will include NHS staff in patient-facing roles; other key workers such as the police and fire service; workers in essential parts of the economy such as public transport; carers of vulnerable people and people working in social care; and people following guidance from Test & Trace. Tests are also needed by schools where testing of pupils is taking place.

We also need to look at the costs of supplying these tests and determine what we can afford to spend on them. Although the tests are supplied at no cost to the public, they are not free and will come at a considerable cost to the taxpayer. Access to diagnostic services and other health services always has to be limited; and based on factors such as clinical need, health outcomes, and cost-effectiveness. The same rules should apply to lateral flow tests so that the maximum benefit is obtained from spending on covid-19 tests.[6]

With the UK now facing record numbers of people with covid-19, we need the government to act quickly, decisively and rationally to ensure we maximise the benefits of England’s covid-19 testing capacity. Lateral flow tests can play an important in England’s pandemic response but the same principles of prioritisation should apply in their use as in any other area of healthcare provision.

A version of this article was first published in the British Medical Journal.

References

  1. Majeed A. Questions and Answers about Lateral Flow Tests for Covid-19.https://blogs.imperial.ac.uk/medical-centre/2021/12/23/questions-and-answers-about-lateral-flow-tests-for-covid-19/
  2. Walker P.100,000 key workers in England told to take Covid test every working day. https://www.theguardian.com/world/2022/jan/04/100000-key-workers-in-england-told-to-take-covid-test-every-working-day
  3. Majeed A. Of course England is running out of Covid tests – the strategy is a flawed one.https://www.theguardian.com/commentisfree/2021/dec/30/running-out-covid-tests-strategy-flawed
  4. Johnson B. PM statement to the House of Commons on COVID-19: 5 January 2022.https://www.gov.uk/government/speeches/pm-statement-to-the-house-of-commons-on-covid-19-5-january-2022
  5. Majeed A, Molokhia M. Vaccinating the UK against covid-19 BMJ 2020; 371 :m4654 doi:10.1136/bmj.m4654
  6. Raffle A E, Gill M. Mass screening for asymptomatic SARS-CoV-2 infection BMJ 2021; 373 :n1058 doi:10.1136/bmj.n1058.

Questions and Answers About New Variants of SARS-CoV-2

Why are some scientists concerned about the new Covid variant that has been found in France?

Whenever a new variant of the coronavirus that causes Covid-19 is identified, there are always concerns that it may prove to be more infectious than previous variants and spread quickly in the population. We saw this previously with the Alpha, Delta and Omicron variants, each of which spread rapidly in the UK, leading to waves of infection that put a lot of pressure on the NHS.

Should we be worried, and why?

The B.1.640.2 variant was first identified over a month ago and so far, it has not caused the massive global spike in Covid-19 cases we have seen with the Omicron variant. There is now very good identification of variants in many countries, so that the spread of a new variant can be monitored. If a variant is spreading rapidly, the World Health Organization will label it as a Variant of interest (VOI) or a Variant of Concern (VOC) depending on its severity. This has not happened yet with B.1.640.2. We should remain cautious, monitor the spread of any new variant, including B.1.640.2, but not get over-anxious.

Both Omicron and the new variant appear to have emerged in Africa, which has the lowest vaccination rate. Is that the reason?

Variants can emerge anywhere. The Alpha variant was first identified in the South-East of England and the Delta variant was first identified in India.

Will it become normal for variants to emerge and spread around the world like Omicron?

The coronavirus that causes Covid-19 will mutate constantly. Most mutations are of no great consequence but occasionally a mutation will appear that can cause a wave of infections – such as the Alpha, Delta and Omicron variants. We may well see other variants emerge and spread around the world in the future.

Are variants getting milder, or is it possible that another variant will be deadlier?

There is no guarantee that a variant will be milder. The Alpha and Delta variants were shown to be more likely to cause a serious illness that the original version of the Coronavirus. In the case of Omicron, the evidence thus far shows that it generally causes a milder illness than other variants. However, because of the very large number of Omicron cases, some people will still have a serious illness.

Could Omicron bring about the end of the coronavirus pandemic?

It’s unlikely that Omicron will bring an end to the Coronavirus pandemic. However, with updated vaccines that can target a new variant such as Omicron and antiviral drugs that can be used early in an illness, we can suppress the severity of disease caused by Covid-19 and allow people to live more normally.

If the world has to live with Covid, what might that look like?

This will vary from country to country. In the UK, high levels of vaccination – including with a modified booster vaccine later this year to target Omicron if the government approves this – combined with antiviral drugs will allow our society to function more normally. Countries with low vaccination rates and weak health services are still likely to face large waves of infection. It’s possible that we will need regular vaccinations – as for flu – to allow us to live with Covid-19. It is also always possible that a variant will emerge against which vaccines are less effective. But the good news is that vaccine manufacturers can modify their vaccines quickly if this happens.

Why is the booster important for Omicron?

The immunity provided by Covid-19 vaccines weakens after a few months. A booster vaccine substantially increase people’s protection from serious illness, including from Omicron. Ensuring that people are fully vaccinated with three doses of vaccine will reduce the number of people who are seriously from Covid-19, and keep down pressures on the NHS.

A version of this article was first published in the Daily Mirror.

Impact of climate change on infectious diseases in the Eastern Mediterranean and the Middle East Region

The Eastern Mediterranean and Middle East (EMME) region has rapid population growth, large differences in socio-economic levels between developed and developing countries, migration, increased water demand, and ecosystems degradation. The region is experiencing a significant warming trend with longer and warmer summers, increased frequency and severity of heat waves, and a drier climate. Our paper in the Climate Change journal discusses the impact of climate change on infectious diseases in the region.

While climate change plays an important role in contributing to political instability in the region through displacement of people, food insecurity, and increased violence, it also increases the risks of vector-, water-, and food-borne diseases. Poorer and less educated people, young children and the elderly, migrants, and those with long-term health problems are at highest risk. A result of the inequalities among EMME countries is an inconsistency in the availability of reliable evidence about the impacts on infectious diseases.

To help address this gap, a search of the literature was conducted as a basis for related recommended responses and suggested actions for preparedness and prevention. Since climate change already impacts the health of vulnerable populations in the EMME and will have a greater impact in future years, risk assessment and timely design and implementation of health preparedness and adaptation strategies are essential.

Joint national and cross-border infectious diseases management systems for more effective preparedness and prevention are needed, supported by interventions that improve the environment. Without such cooperation and effective interventions, climate change will lead to an increasing morbidity and mortality in the EMME from infectious diseases, with a higher risk for the most vulnerable populations.

DOI: https://doi.org/10.1007/s10584-021-03300-z

Lifestyle actions to improve your health in 2022

The last two years have been a difficult time for people all over the world because of the still ongoing Covi1-9 pandemic. Here are some lifestyle choices you can make to improve your health in 2022.

1. Attend your Covid-19 vaccine appointments

2. If a modified Covid-19 vaccine is offered in 2022, get it

3. Wear a well-fitting FFP2 mask when needed

4. Don’t Smoke

5. Exercise regularly

6. Eat 5 portions of fruit & vegetables every day

7. Eat plenty of high-fibre foods

8. Limit your sugar & salt intake

9. Limit your alcohol intake

10. Take time to improve your mental health

11. Take time off work for holidays

12. Make time for friends and family

13. Check your blood pressure

14. Get a good night’s sleep

15. Listen to experts on health issues and not random people on social media

16. Don’t spend too much time on social media

Of course, our health is determined by many other important factors – such as income, poverty, education, housing, employment and the environment. We need to work together to tackle these important issues.

Rational use of lateral flow tests for Covid-19

In recent days, it has become very clear that there are nowhere nearly enough lateral flow tests for Covid-19 in England to allow the government’s policy of their indiscriminate use. Even if funding could be found to buy more tests, it is unlikely to government could source enough tests to meet current and future demand because of the many other countries that are also trying to obtain the tests as they struggle to control the wave of infections from the Omicron variant of SARS-CoV-2.

The government is in part to blame for the current problems with the increased demand tests. It has encouraged members of the public to test regularly; for example before social events such as parties; and before meeting friends and family from outside their immediate household. The very high level of Covid-19 cases in the UK (with around 183,00 cases reported on 29 December) also means that many more people will have been advised to test regularly in line with guidance from Test and Trace. This will include guidance for close contacts of cases who are asked to carry out daily tests for 10 days if they are fully vaccinated to avoid isolating. People with a Covid-19 infection can also test themselves on day 6 and day 7 of their illness, and end their period of isolation if they are asymptomatic and the two tests are both negative.

What can we do to improve how well lateral flow tests are used? The first step is for the government to publish data on the daily supply of tests. We then need clear guidance from the government on what groups should be prioritised for testing and how frequently they should test. Carrying out several tests in one day is not a good use of these tests. And nor is carrying out daily lateral flow tests after a positive PCR test (other than on day 6 & 7 as discussed above). Even daily tests are inappropriate in asymptomatic people when there is currently such a large gap between the supply and demand for tests. NHS guidance is for staff to test twice per week with a lateral flow test but many asymptomatic people are testing more frequently than this. NHS Trusts and general practices need to review their testing polices and give clear guidance to staff to protect the supply of tests.

Once we have information on the daily supply of tests, we can then prioritise who will have access to the tests. This kind of prioritisation is quite normal in healthcare and was done, for example, with Covid-19 vaccination to ensure access was given based on clinical and occupational priority. Groups for priority access to tests should include:

– NHS staff in patient-facing roles

– People working in social care

– Teachers and other people working in schools

– Workers in essential parts of the economy such as public transport

– Groups such as HGV drivers to ensure that deliveries of essential items continues

– Patients who are clinically vulnerable

– People following guidance from Test & Trace

There is also now a lack of PCR for tests to diagnose Covid-19. An important question for the government is should we use lateral flow tests to give better access to testing for people with symptoms and reduce testing for people who are asymptomatic? If this does happen, we will still need to decide and which groups would have access to lateral flow tests in place of PCR tests. Successful implementation of this policy could allow many more people to receive a test. Although lateral flow tests are not as sensitive as PCR tests, they will still identify many people with Covid-19.

We also need to look at the costs of supplying these tests and determine what we can afford to spend. Although the tests are supplied at no cost to the public, they are not free and will come at a considerable cost to the taxpayer. Access to diagnostic services and other health services always has to be limited; and based on factors such as clinical need, health outcomes, and cost-effectiveness.

With the UK facing record numbers of people with Covid-19, we need the government to act quickly, decisively and rationally to ensure we maximise the benefits of England’s Covid-19 testing capacity.

A version of this article was first published in the Guardian Newspaper.

Questions and Answers about Lateral Flow Tests for Covid-19

Lateral flow tests are now being used by many members of the public. In this blog, I answer some of the common questions that people ask about these tests, which I was asked to comment on for articles for the Guardian Newspaper and VICE UK.

How do lateral flow tests work and how reliable are they?

Lateral flow test (LFTs) work by detecting the proteins on the surface of the SARS-CoV-2 virus that is the cause of Covid-19. They can be carried out at home and don’t require a laboratory to process the test, unlike PCR tests. They also give a result very quickly, typically within 30 minutes. They are less accurate than PCR tests, which is why PCR tests are recommended for people with symptoms.

Studies show widely varying estimates of the accuracy of LFTs, typically detecting between 40%-90% of people who have Covid-19 in different studies. We can’t just take an average of these studies to determine the accuracy of the tests as this will depend on a range of factors – such as the type of people in the study, what stage of illness they were at, what specific test was used, and how well the test was carried out.

We do know that carrying out the test correctly is very important. It’s essential therefore to read the instruction leaflet that comes with the test and to watch one of the NHS videos that explain how to carry out a lateral flow test to learn the correct technique.

How do I carry out a lateral flow test?

Before you start, read the instructions that came with the test. If your test needs a throat swab, open your mouth wide and rub the swab over your tonsils (or where they would have been if you have had a tonsillectomy). Put the same swab inside your nose (about 2.5 cm / one inch up or until you feel resistance). If your test requires only a nose swab, put the swab inside your nose (about 2.5 cm / one inch).

After you have done this, put the end of the swab into the tube so it’s in the liquid, then squeeze the liquid from the tube onto the test strip and read the test result once the waiting time advised in the instruction leaflet has passed. Once you have the result, record this via the reporting website. This is important as it allows the government and the NHS to monitor Covid-19 infections in the UK.

Full instructions on how to carry out the test are available on the NHS Website. There are also several NHS videos available online that show people how to use the tests properly.

People online have had negative lateral flows but positive PCRs – why is this? Should I get a PCR instead?

Lateral flow tests and PCR tests work in different ways. Lateral flow tests detect some of the proteins in the virus, can be carried out at home and give a result quickly. PCR tests detect the genetic material (RNA) in the virus and require a laboratory to do this. The result of a PCR test takes longer to come back but it will pick up more infections than a lateral flow test because the test has a higher sensitivity than a lateral flow test.

Because lateral flow tests are not as accurate as PCR tests, they can sometimes be negative in people with symptoms when the subsequent PCR test is positive. If you have symptoms of a possible Covid-19 infection, you should always get a PCR test and not rely on a lateral flow test. If you don’t have symptoms, a lateral flow test is sufficient. PCR tests should be reserved for people with symptoms of a possible Covid-19 infection to avoid overloading government laboratories with unnecessary test requests.

What are the symptoms of a Covid-19 infection?

When Covid-19 first arrived in the UK in early 2020, the main symptoms people were asked to look out for were a high temperature, a new continuous cough, or a loss or change to their sense of smell or taste. Now that so many people in the UK have some immunity because of vaccination or a previous Covid-19 infection, they may get other symptoms when infected – such as a headache, runny nose, sore throat, or sneezing. So even if you think you might just have a cold, you should still get a PCR test.

How long before meeting family/friends should you take one, and does taking multiple LFTs increase their accuracy?

The test should be done on the day of the meeting. One test is sufficient. Although you can carry out more than one test a day, there is a shortage of tests in many parts of England. If the tests are over-used, this will lead to further supply problems – including for key workers such as NHS staff who are required to test regularly for employment purposes.

Does the thickness of the ‘test’ line on an LFT give any indication of how infectious you are? (if it’s a weak line, does that mean you are hardly shedding any virus? Does a thick one mean you are really infectious?)

The test is designed to tell you if you may be infected and is not designed to estimate how infectious you may be. You shouldn’t therefore use the thickness of the line to try to estimate your infectivity. At a time when the prevalence of Covid-19 in the UK is so high, a positive test means that you are very likely to be infected and you should isolate until you get the result of a PCR test; and then isolate further if this is positive.

If you are still testing positive on an LFT after 10 days’ isolation, are you still infectious and do you still need to isolate? (MIT medical journal says: “But what if someone still tests positive after 10 days? This is very common. People who have tested positive for COVID-19 are very likely to continue to test positive after 10 days. But they are not contagious.”)

There is no need to keep on testing repeatedly if you have had a positive LFT result and this is then confirmed by a PCR test. You should complete your period of isolation and, if in England, carry out any required LFTs as advised by NHS Test and Trace. In England, people who are fully vaccinated can now carry out LFTs on day 6 and day 7 of their isolation period and come out of isolation if both these tests negative. Unvaccinated people will need to continue to isolate for 10 days. Test results can sometimes remain positive for a period after day 10 of isolation ends but this not necessarily mean you are still infectious.

If you’ve tested positive, including for Omicron, does that mean you won’t get it again?

Reinfections can occur after a previous Covid-19 infection. These are more common with Omicron which a recent study from Imperial College London showed was over 5-times more likely to cause a reinfection than the Delta variant. These reinfections will have been in people who have had an infection with a variant such as Delta, Alpha or the original version of SARS-CoV-2. Because Omicron infections have only occurred recently in the UK, we don’t yet know how prone people who have had an Omicron infection will be to a repeat infection.