Coronavirus and behaviour of the vaccinated population after being in contact with a positive case in England: 25 to 30 October 2021

• The COVID Test and Trace Contacts Behavioural Insights Study was compiled in response to policy questions about the behaviour of contacts of a positive coronavirus (COVID-19) case, who were not required to self-isolate because of being fully vaccinated; this is the first bulletin of the series.
• Data collected from 25 to 30 October 2021 show that the majority (91%) of respondents reported that they had taken a COVID-19 test (lateral flow or PCR) since being contacted by NHS Test and Trace or via the app.
• Of those who reported taking a test, a minority (13%) reported testing positive for COVID-19.
• Of those who received two doses of the vaccine, 82% did not develop symptoms, compared with 96% of those who had received two doses and the booster dose; this was a statistically significant difference.
• The majority (84%) of respondents said that double vaccinated contacts should take a PCR test after having been in contact with someone who has tested positive for COVID-19.
• Around 2 in 3 (63%) respondents reported taking additional measures to keep themselves and others safe beyond government guidelines and recommendations.
• Respondents estimated that 65% of the population of England would follow self-isolation guidance if they tested positive, compared with 92% of their own friends and family.

Since 16 August 2021, people in England who are double vaccinated are no longer legally required to self-isolate if they are identified as a close contact of a positive coronavirus (COVID-19) case. Instead, NHS Test and Trace provide individuals with advice on testing and give guidance on preventing the spread of COVID-19.

The data presented in this bulletin were collected from individuals (“contacts”) who had been identified as having been in contact with someone who had tested positive for COVID-19, and who were exempt from self-isolation because of being double vaccinated. Analysis of contacts required to self-isolate is available in Coronavirus and self-isolation after being in contact with a positive case in England.

More information on identifying this group of people and collecting the data can be found in the Glossary and Measuring the data sections.

Between 25 and 30 October 2021, the majority (91%) of respondents reported that they had taken a COVID-19 test (lateral flow or PCR) since being contacted by NHS Test and Trace or via the app. Of those who reported taking a test, 13% said they received a positive result. This was similar among different age groups.

Since being contacted by NHS Test and Trace or the app, 16% of respondents developed symptoms of COVID-19. Of those who developed symptoms, 61% reported already having symptoms or developing them the day of being contacted. A further 17% developed symptoms one to two days after being contacted. Of those who developed symptoms, the most common symptoms reported were runny or stuffy nose (71%), headaches (68%), and unusual tiredness and fatigue (63%).

Of those who developed symptoms, 85% said they had taken a test. Of these, 68% tested positive for COVID-19.

Of those who received two doses of the vaccine, 82% did not develop symptoms, compared with 96% of those who had received two doses and the booster dose. This was a statistically significant difference.

Figure 2 shows the change in frequency of behaviours before and after being contacted by NHS Test and Trace.

Before being contacted by NHS Test and Trace, 81% of respondents said they took coronavirus (COVID-19) tests. Of those, 44% reported taking COVID-19 tests more often since being contacted. This was significantly lower among those aged 55 years and over (29%), compared with those aged 18 to 34 years and 35 to 54 years (50% in both age groups).

A minority (15%) of respondents reported that they were currently self-isolating. The main reasons given for self-isolating were that they had tested positive for COVID-19 (73% of people who were self-isolating) and had symptoms of COVID-19 (14% of people who were self-isolating).

The majority (71%) of respondents reported they were either very or moderately confident in their understanding of the rules about self-isolation for those who are double vaccinated. The remaining 29% of respondents reported being either "not at all", "slightly", or "somewhat" confident in their understanding of the rules.

Respondents were asked about their understanding of what a double vaccinated person who comes into contact with someone who has tested positive for coronavirus (COVID-19) should do, based on government guidance. One fifth (20%) reported that people should do nothing and carry on as usual. This was statistically significantly higher among those aged 55 years and over compared with those aged 35 to 54 years.

Around 2 in 3 (63%) of respondents reported taking additional measures to keep themselves and others safe, beyond government guidelines and recommendations.

Respondents who took a coronavirus (COVID-19) test after being contacted and received a result that was not positive were asked how willing they would be to share details of their close contacts with NHS Test and Trace if they were to test positive. On a scale from 1 (“not willing”) to 10 (“completely willing”), the average willingness was 9.4. Willingness to share details was similar in males and females and across age groups.

Respondents were asked their opinions on the proportion of people who would follow self-isolation guidance if they tested positive for COVID-19. On average, respondents estimated 65% of the population of England would follow the self-isolation guidance if they tested positive. When thinking about their own friends and family, respondents estimated 92% would follow self-isolation guidance.

The majority (80%) of respondents reported that being contacted by NHS Test and Trace had no effect on their well-being and mental health. A further 15% reported that being contacted had a negative effect, and the remaining 5% reported a positive effect.

The average life satisfaction score was 7.7 on a scale from 0 (“not at all satisfied”) to 10 (“completely satisfied”). This was significantly higher than the average life satisfaction score for the general adult population of England (7.0).

Contacts not required to self-isolate

From 16 August 2021, close contacts of someone with coronavirus (COVID-19) were not required to self-isolate if they had been fully vaccinated. Fully vaccinated refers to having been vaccinated with a Medicines and Healthcare products Regulatory Agency (MHRA) approved COVID-19 vaccine in the UK and at least 14 days have passed since having received the recommended doses of that vaccine.

When identified as a contact, NHS Test and Trace contact individuals and check whether they are legally required to self-isolate. Even if they have no symptoms, contacts will be advised to have a PCR test as soon as possible. Guidance is also given on preventing the spread of COVID-19, which states for the 10 days following contact with the positive case, people may want to consider:

• limiting close contact with people outside your household, especially in enclosed spaces
• wearing a face covering in enclosed spaces and where you are unable to maintain social distancing
• limiting contact with anyone who has an underlying health condition that puts them at higher risk of severe illness if infected with COVID-19
• taking part in twice-weekly lateral flow testing

If a contact subsequently tests positive for COVID-19 they must follow the legal requirement to self-isolate.

More information can be found in Guidance for contacts of people with confirmed coronavirus (COVID-19) infection who do not live with the person. Please note this guidance is updated regularly.

Self-isolation

Self-isolation is when individuals do not leave their home because they have, or might have, COVID-19.

Statistical significance

The term "significant" refers to statistically significant changes or differences. Significance has been determined using the 95% confidence intervals, where instances of non-overlapping confidence intervals between estimates indicate the difference is unlikely to have arisen from random fluctuation. More information is available on our uncertainty webpages.

Survey information

This is the first bulletin in this series, with the survey in its current format and using the current data collection methodology.

The COVID Test and Trace Contacts Behavioural Insights Study aims to understand the behaviour, attitudes and well-being of individuals identified as a contact of someone who has tested positive for coronavirus (COVID-19) and does not need to self-isolate because of being fully vaccinated. This survey was specifically designed in consultation with Office for National Statistics (ONS) experts to obtain information on this group of people.

Estimates for this survey

The data were collected between 25 and 30 October 2021. The sample was stratified to be representative of the age, sex and regional distribution of the fully vaccinated “contacts” population in England. The achieved sample consisted of 1,100 adults.

Percentages in this report are based on weighted counts that are representative of the population of adults (aged 18 years or over) who had received at least two doses of a COVID-19 vaccine and were notified as being in contact with someone who tested positive for COVID-19 between 27 September and 24 October 2021.

The survey was conducted via telephone and all answers were self-reported. Of those potential respondents who were successfully contacted by an interviewer, the response rate was 67.1%. When including cases where contact was attempted but not made, the response rate was 17.4%. As with all surveys, these estimates have an associated margin of error.

Respondents were randomly sampled through the Contact Tracing and Advice Service (CTAS) database, held by NHS Test and Trace. The sample was limited to those who were fully vaccinated, had provided a valid phone number and who had been entered onto the CTAS database at the point of sampling. A random sample was selected from a sample frame which included all contacts whose date of exposure was 15 or 18 October 2021.

The main strengths of the COVID Test and Trace Contacts Behavioural Insights Survey include:

• timely production of data and statistics that can respond quickly to changing needs, as the questions included are reviewed for each survey wave
• the sample was stratified to be representative of the age, sex and regional distribution of the population being sampled and percentages are based on weighted counts representative of the population
• quality assurance procedures are undertaken throughout the analysis stages to minimise the risk of error
• confidence intervals have been used to determine whether differences across time periods and groups are statistically significant

The main limitations of the COVID Test and Trace Contacts Behavioural Insights Survey include:

• because of the limited period in which fieldwork took place, it is difficult to reach a large number of people and therefore the overall sample size for the survey is limited
• the behaviour during the 10 days following exposure to coronavirus (COVID-19) was self-reported and may be subject to recall bias, which influences how accurately respondents can recall past events and experiences; most interviews took place around 10 days following exposure to reduce this bias
• the Experimental Statistics presented contain uncertainty; as with all survey data based on a sample, there is an element of uncertainty as they are susceptible to respondent error and bias
• because of the nature of the target population, in which a large proportion of contacts are members of the same household, it is possible that the sample could include multiple members of the same household