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The COVID-19 pandemic has had, and continues to have, a profound impact across the UK. This study aims to find out how many people are still getting the infection and how many are likely to have had the infection, even if they haven’t realised it at the time. This is particularly important as more people start getting vaccinated against COVID-19. Although the vaccine works very well, it is not 100% protective, and it is necessary to monitor how well it works in the real-world.

One way to find out whether a person has an infection is to directly look for the virus in their nose and throat. The main test used to diagnose COVID-19 uses a swab taken from someone’s nose and throat. Once an individual has recovered from the infection, the virus cannot be found any longer. One way the body fights infections like COVID-19 is by producing small particles in the blood called “antibodies”. It takes 2-3 weeks for the body to make enough of these antibodies to fight the infection. But once a person recovers, they still stay in the blood at low levels and give some protection against future infection. Getting vaccinated against COVID-19 is another way that people can get antibodies that can protect them against getting COVID-19. So scientists try to measure levels of both the virus and these antibodies to work out who has COVID-19 now (with or without symptoms) and who has had it in the past, or has developed antibodies against it after getting vaccinated.

In this study we want to find out how many people of different ages across the UK have COVID-19 over time, particularly as more people get vaccinated, and how many have had COVID-19 in the past. We do this by testing for the virus in the nose and throat of people and by measuring levels of antibody in the blood. We also want to find out how many people have COVID-19 with symptoms or without knowing they have the infection because they don’t have any symptoms. We want to do this in a group of people that reflects the population of the UK – so a range of ages and places where people live. We will ask everyone aged 2 years or older in each randomly selected household to have a nose and throat swab, and for those aged 12 years and older to answer a few short questions at a home visit undertaken by a trained individual (parents/carers will answer for younger children). Those aged 12 years and older can take their own swabs using self-swabbing kits, and parents/carers will use the same kits to take swabs from their children aged 2-11 years. This is to reduce the risk to the study workers. We will ask adults aged 16 years or older from a randomly selected subset of these enrolled households to also give a sample of blood. At the start of the study, this was taken from a vein by a trained nurse, phlebotomist or healthcare assistant, but now we are moving towards it being taken by a fingerprick by the participant themselves so that all visits can happen without study workers and participants needing to come into close contact (<2m). 

We will ask people who have this first home visit whether they would be happy to have the same kind of visit and nose and throat swabs repeatedly, every week for the first month (swab and questionnaire only, no blood draw), and then every month from their first visit for a year (including monthly blood draws for those with blood taken originally). This is to find out how rates of infection and immunity change over time in individual people, and whether they can get the virus again with or without having symptoms.

So far over 440,000 people from around 220,000 households across all four nations of the UK have taken part in the study. Currently we are aiming to achieve up to ~150,000 individuals swabbed at least every fortnight from October 2020 onwards in England, ~9,000 in Wales, ~5,000 in Northern Ireland and ~15,000 in Scotland (~179,000 total across the UK) (absolute numbers reflecting the relative size of the underlying populations). We are aiming to take blood from up to ~125,000 people giving blood samples every month in England, and up to ~7,500, ~5,500 and ~12,000 per month in Wales, Northern Ireland and Scotland (~150,000 in total across the UK). This is to monitor how vaccination affects immunity at both the population and the individual level.

This information will help scientists and the government work out how to manage the pandemic over the coming months and protect the NHS from being overwhelmed.

Any questions about how the survey is running on the ground should be sent to

If you are a participant, or a potential participant, and wish to complain about any aspect of the way in which you have been approached or treated, or how your information is handled during the course of the survey, please contact the dedicated study team on or 0800 085 6807. Please do not contact the Nuffield Department of Medicine, as they will not be able to help you, and will not reply to general enquiries or questions about operational issues relating to the study.

You can find out more details of the study through its registration on ISRCTN21086382.