COVID-19 Infection Survey

The Covid-19 pandemic is having a profound impact across the UK. This study aims to find out how many people have the infection and how many are likely to have had the infection, even if they haven’t realised it at the time.

One way to find out whether a person has COVID-19 infection is to directly look for the virus. The main test we are using to diagnose it at the moment does this in a swab taken from someone’s nose and throat. Once someone has recovered from the infection, the virus is no longer present. But, 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 – this is what helps them not get the same infection again. 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.

In this study we want to work out how many people of different ages across the UK have Covid-19 now 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 over time – either 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 reflect the population of the UK – so a range of ages and places where people live. We will begin by inviting 20000 households to participate with an assumed 50-60% opt-in rate, and a target enrolment of 11,000 households. We will be asking everyone aged 2 years or older in each 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 health workers. We will ask adults from around 1000 of these enrolled households aged 16 years or older to also give a sample of blood which will be taken by a trained nurse, phlebotomist or healthcare assistant. We will take swabs from all households, whether anyone is reporting symptoms or not. We will not take blood from anyone in a household where someone has symptoms compatible with Covid-19 infection, or is currently self-isolating or shielding, to make sure that study staff stay at least 2m away from them at all times. The trained study health workers will use all the recommended precautions to protect themselves and everyone in the household from getting the virus.

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.

We will do an enrolment home visit with invitations being sent to a new group of 20,000 households approximately every month, targeting recruitment of around 11,000 households. This is to find out how the number of people infected at any one time, the levels of immunity to Covid-19, and the rates of infection with and without symptoms, are changing across the country.

This information will help scientists and the government work out how to manage the pandemic better moving forwards and protect the NHS from being overwhelmed.

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


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