Test, trace and isolate programmes across the UK are under pressure as COVID-19 cases rise in all age groups and demand for tests grows. Further pressure comes from people seeking tests because they have symptoms caused by other respiratory viruses but need a test in order to rule out COVID-19. The Scientific Advisory Group on Emergencies has described the impact of current test and tracing on the transmission of the virus as “marginal”. How does test and trace work and what are the current challenges limiting its effectiveness in reducing COVID-19 cases?
On 9 September, the Prime Minister announced a moonshot plan for mass COVID-19 testing. Recently there have been capacity issues in the NHS Test and Trace programme and current technologies cannot be scaled easily to millions of tests per day. So, how is COVID-19 testing undertaken, how reliable are current tests, and what technologies or strategies are emerging that would make this moonshot feasible?
Testing people to see if they are currently infected or previously infected with SARS-CoV-2, the virus that causes COVID-19, is a key component of medical management, public health monitoring and research. Diagnosing people as having active infections is a fundamental part of any test and contact tracing system. Improving the speed and accuracy of tests that detect current infections is a research priority and the focus of recent UK Government investment and policy decisions. Antibody tests are also an important tool to understand how many people in the population have been infected and how their immune system responded.
Seasonal influenza occurs every year, is a key driver for winter pressure on the NHS and a leading cause of excess deaths every winter. The influenza season, together with other respiratory infections, is likely to coincide with COVID-19 this winter. Those most at risk from influenza are also most vulnerable to COVID-19.
While there is some evidence for the use of face masks and face coverings, it is weak and highly situational. Face masks are no substitute for social distancing. Hand hygiene and good respiratory etiquette, remain the best ways to limit the spread of coronavirus.
Children who have COVID-19 are not likely to develop severe symptoms. They are also much less likely to die from the disease than people in older age groups. there is some evidence on infection risk for under 13s and for BAME children but more data from well-designed studies is needed to draw conclusions.
There is very good evidence that children who have COVID-19 are much less likely to develop severe symptoms and much less likely to die from the disease than people in older age groups.There is good evidence that children under 13 years old are less susceptible to developing clinical disease (this means having recognisable signs and symptoms) than adults. It is not yet clear whether this is also the case for older children. There is some research indicating that children aged 13 years and under may be less susceptible to infection than adults, but the confidence in this evidence is low. There is insufficient research to say whether this is the case for older children. There is some evidence to suggest that children transmit the virus less than adults, but more research is needed to reduce uncertainty. Children are more likely to catch an infection from adult(s) in their household. There is evidence that schools are a low-risk environment for transmission. There are some limited data suggesting that children from a black, Asian or minority ethnic background may be at higher risk of severe disease, consistent with evidence for adults. Large and well-designed studies are needed in order to draw firm conclusions.
Pregnant women are not more likely to contract the virus. Transmission of the virus from mothers to babies is low. Some babies born to COVID-19 positive mothers will develop an infection; these babies are not at increased risk of severe disease.
This article was updated on 1 May and again on 6 July. Since its original publication on 17 April, the number of COVID-19 clinical trials has increased from 524 to 2,378. There is no cure for COVID-19. Researchers are testing existing drugs to see if they act against SARS-CoV-2 or alleviate the symptoms of the disease. New drugs are also in development, but this is at a very early stage. Results from trials on existing drugs have already been reported with some positive findings. Dexamethasone is a cheap steroid drug that reduces the risk of death of ventilated patients by 35% and by 20% for patients requiring oxygen therapy. Remdesivir is an antiviral drug; there is good evidence that it can reduce the length of time that hospitalised COVID-19 patients are ill. Negative findings are valuable because they allow researchers to focus on other drugs; there is good evidence that hydroxychloroquine does not offer any benefits to treat COVID-19 patients. Research to see if it might have a protective effect for at-risk groups, such as healthcare workers, is ongoing. There are numerous trials in progress to test a range of drugs that act on the immune system.
An infected person produces respiratory droplets when talking, coughing and sneezing. These are responsible for the transmission of virus between people. Droplets can travel up to 2m, with finer aerosols containing smaller viral particles travelling even further. Numerous complex and interacting factors influence how they move and settle onto surfaces, and how infectious they are. The further away a person is, the fewer droplets they will be exposed to and so their risk of being infected with the virus reduces. The advice on 2 m distancing is a risk assessment based on relative not absolute risk; 2 m does not represent zero risk. Measures to mitigate the increased risk of reducing physical distancing include ventilation, physical barriers (screens and face coverings), reduced building occupancy and enhanced cleaning. These will vary according to the context. The wider range of social distancing practices will need to be maintained to contain viral transmission even if the 2 m advice changes. Social distancing and other public health measures are likely to be needed long-term, until a vaccine or more effective treatments for COVID-19 are available.
There are numerous knowledge gaps about SARS-CoV-2 transmission; research to address them will inform policy-making.
There is insufficient scientific evidence to know whether the presence of SARS-CoV-2 antibodies confers protection from subsequent infections, and if so at what level. Antibodies are only one part of the immune response to infection. Tests that detect SARS-CoV-2 antibodies are available. They can determine whether someone has had COVID-19. Tests can reveal those who are unaware that they had COVID-19 because they had mild or no symptoms. Test samples must be analysed in a laboratory – no home tests are authorised for use in the UK. The Government provides antibody tests for NHS and social care staff, hospital patients and care home residents. Commercial test kits are available for private use. These are of varying quality and results must be interpreted with caution. A positive test does not necessarily mean that someone will be protected from subsequent infections. There are concerns that access to private tests of variable quality will discourage the public from practising effective public health measures. Antibody tests are an important tool to understand the spread of the virus and how many people in a population have been infected. They are being used in infection surveillance surveys in the UK and elsewhere.
Scientific understanding of the immune response to COVID-19 is incomplete but numerous research studies are underway. There is little evidence to suggest that exposure to other coronaviruses can confer protection against SARS-CoV-2. There is very good evidence that it takes at least 14 days to develop an antibody response to SARS-CoV-2. A significant proportion of people exposed to SARS-CoV-2 make very little or no detectable antibodies at all. There is insufficient scientific evidence to know whether the presence of SARS-CoV-2 antibodies confers protection from subsequent infections, and if so at what level. The duration of immunity is not clear; long-term monitoring of this in large studies will be needed to provide clarity. Antibodies are only one part of the immune response to infection, which is complex, and understanding the overall immune response to COVID-19 is very important. Additional high-quality research evidence is needed in order to indicate the likelihood of future outbreaks of disease, how often and when they are likely to occur, and to inform the development of any future immunisation programmes.
There is very good evidence that children who have COVID-19 are much less likely to develop severe symptoms and much less likely to die from the disease than people in older age groups. There is good evidence that children under 13 years old are less susceptible to developing clinical disease (this means having recognisable signs and symptoms) than adults. It is not yet clear whether this is also the case for older children. There is some research indicating that children aged 13 years and under may be less susceptible to infection than adults, but the confidence in this evidence is low. There is insufficient research to say whether this is the case for older children. There is some evidence to suggest that children transmit the virus less than adults, but more research is needed to reduce uncertainty. Pregnant women are not more likely to contract the virus. Transmission of the virus from mothers to babies is low. Some babies born to COVID-19 positive mothers will develop an infection; these babies are not at increased risk of severe disease.
The UK Government announced its approach to exiting lockdown on 10 May in a statement by the Prime Minister and in a report published on 11 May. Current models suggest that 5.38% of the UK population has been infected with COVID-19. To lift restrictions the World Health Organisation has outlined key criteria that should guide decision making, such as ensuring that health systems can identify, isolate, test, trace contacts and quarantine COVID-19 cases. Several countries have eased measures with varying success including, Austria, France, Germany, Italy, Spain and China. Other countries such as Sweden and South Korea have taken alternative routes.
This article goes over the types of masks that exist. It explores how effective are they at preventing transmission of coronavirus, according to the latest research. It reviews the advice on masks and face coverings from public health organisations, and presents official guidance from several nations. This is part of our rapid response content on COVID-19. You can view all our reporting on this topic under COVID-19.
Who is working on a vaccine to prevent COVID-19 (coronavirus disease)? When might a COVID-19 vaccine become available?
This is part of our rapid response content on COVID-19. You can view all our reporting on this topic under COVID-19. This article will be updated as the research progresses.