Woman working in laboratory

The Real-time Assessment of Community Transmission (REACT) programme is the largest, most significant piece of research looking at how the virus is spreading across the country. 

The study is being carried out by a world-class team of scientists, clinicians and researchers at Imperial College London, Imperial College Healthcare NHS Trust and Ipsos MORI, and was commissioned by the Department of Health and Social Care.

REACT study findings 

18 November - community infection trends (REACT-1 round 15 final)

These findings from the 15th round of the REACT-1 study look at swab tests from over 100,000 people across England between 19 October and 5 November. They showed that infections doubled since September but have been declining throughout October. 1.57% of people were infected, or 1 in 64. Around 1 in 20 school-aged children were infected. A single vaccine dose in school-aged children cut the risk of infection by more than half, and the risk of symptomatic infection by two-thirds. The risk of infection was almost three times lower in people who had received a booster compared to those who had received two doses.

Click here to read the pre-print report. Report title: 'REACT-1 round 15 final report: Increased breakthrough SARS-CoV-2 infections among adults who had received two doses of vaccine, but booster doses and first doses in children are providing important protection'

Click here to read our news story'COVID-19 vaccination cuts infection risk by half in school-aged children - REACT'

4 November - community infection trends (REACT-1 round 15 interim)

These interim findings from the 15th round of the REACT-1 study look at swab tests from 67,000 people across England. The study recorded the highest prevalence of infection since the programme began in May 2020, with 1.72% of people infected. The highest number of infections were in school-aged children, with 1 in 17 infected. The study also read the viral genetic code of 126 positive samples, findings all were the Delta variant, 10% of which were AY.4.2. sub-lineage which is a variant under investigation.

Click here to read the pre-print report. Report title: 'REACT-1 round 15 interim report: High and rising prevalence of SARS-CoV-2 infection in England from end of September 2021 followed by a fall in late October 2021'

If the above link does not work, use this link to download the report: REACT-1 round 15 interim (PDF)

Click here to read our news story: 'REACT study records highest coronavirus prevalence yet'

2 November - REACT-1 rounds 12 and 13 (peer-reviewed publication)

This study looked at REACT-1 data from 200,000 people across England gathered from rounds 12 and 13, carried out between 20 May and 12 July 2021. It found that despite the highly successful vaccination campaign, infections were increasing exponentially, driven by the Delta variant with high infection prevalence among younger, unvaccinated people. 

Click here to access the peer-reviewed publication in Science. Publication title: 'Exponential growth, high prevalence of SARS-CoV-2, and vaccine effectiveness associated with the Delta variant'

14 October - coronavirus infection trends (REACT-1 round 14)

Findings in brief

This research from the REACT-1 programme looked at data from swab samples taken at home by around 100,000 people in England, between 9 and 27 September. The research found that 1 in 120 people had the virus during this period with R around 1. However infections were high and increasing in school-age children. The study also looked at vaccination effectiveness against infection, and how this changed over time. 

Click here to read the pre-print report. Report title: 'REACT-1 study round 14: High and increasing prevalence of SARS-CoV-2 infection among school-aged children during September 2021 and vaccine effectiveness against infection in England 

Click here to read our news story: 'Coronavirus infections flat in England but rising in school-aged children - REACT'

4 October - assessing the acceptability and performance of lateral flow tests 

Findings in brief

This research from the REACT-2 programme looked at how well people could use a type of finger-prick antibody test called a lateral flow test, and how accurate the tests were at detecting coronavirus antibodies. The research was carried out with non-healthcare key workers. 

Access the peer-reviewed publication in Open Forum Infectious Diseases here. Publication title: 'Acceptability, usability and performance of lateral flow immunoassay tests for SARS-CoV-2 antibodies: REACT-2 study of self-testing in non-healthcare key workers'

28 September - symptoms linked with COVID-19 in the community

Findings in brief

This research looked at data from over a million people in England who have participated in the REACT-1 programme, identifying symptoms that are linked with having the coronavirus. Of the range of symptoms identified, seven were found to be the best predictors of having COVID-19 among symptomatic individuals. If these symptoms were included in testing criteria, the number of infections detected could therefore be increased. 

Access the peer-reviewed publication in PLOS Medicine here. Publication title: 'Predictive symptoms for COVID-19 in the community: REACT-1 study of over 1 million people'

Access the preprint report of the findings from February.

Click here to read our news story: 'COVID-19 linked with wider set of symptoms than previously thought – REACT study'

13 August - duration of swab positivity

Findings in brief

This research from the REACT-1 programme investigated how long people who are infected with the coronavirus shed virus for following a positive test. The research found that people with symptoms, and those infected with the Delta variant, tested positive for a longer period compared to those without symptoms or infected with the Alpa variant. 

9 August - behavioural responses following coronavirus antibody testing

Findings in brief

This study looked at people's behaviours after they tested themselves for coronavirus antibodies as part of the REACT-2 study. The study involved a follow-up survey of almost 9,000 people which was carried out six weeks after they took their test, around half of whom were positive for antibodies and the other half negative. The study didn't find strong evidence that people changed their behaviours after testing positive, in the context of a research study. 

4 August - coronavirus infection trends (round 13 final report)

Findings in brief

The 13th round of the REACT-1 study looked at swab test data from almost 100,000 people in England between 24 June and 12 July. The research found that infections were three times lower in people who were fully vaccinated, compared to unvaccinated people. The data also suggested that people who were fully vaccinated were less likely to pass the virus on to others, due to having a lower viral load on average and therefore shedding less virus. 

22 July - coronavirus antibody survey (REACT-2 round 4)


This study used finger-prick tests (lateral flow devices) to check for coronavirus antibodies in a random sample of 161,500 adults across England. Tests were carried out between 27 October and 10 November 2020. 5.6% of people tested positive for antibodies, a 25% rise compared to previous findings. 

14 July - coronavirus antibody survey (REACT-2 round 6)

Findings in brief

The sixth round of the REACT-2 coronavirus antibody survey looked at data from over 207,000 people in England between 12th and 25th May 2021. The study found that almost 100% of adults had coronavirus antibodies 14 days after receiving their second COVID-19 vaccine dose. The research found high levels of vaccine uptake, although coverage was uneven with men, people living in deprived areas, those working in public-facing roles such as retail and hospitality, and people who identify as Black among those with lower vaccination rates. 

8 July - coronavirus infection trends (interim report)

Findings in brief

An interim analysis of data from the 13th round of the REACT-1 study looks at the prevalence of infection in England, based on swab tests carried out by almost 50,000 people between 24 June and 5 July. The results showed that infections continued to grow exponentially during this period, doubling every 6 days, with the R number at 1.87.

24 June - Symptom reporting in over half a million REACT-2 participants

An analysis of questionnaire data from more than half a million people surveyed as part of our REACT-2 programme found that 1 in 20, or around 6%, had COVID-19 symptoms lasting 12 weeks or more. That means that more than two million people in England may have had long COVID, a poorly understood condition where people experience persistent symptoms after being infected with the coronavirus. Women, people who smoked, were overweight or obese, or lived in deprived areas, all had a higher risk of experiencing persistent symptoms. The risk also increased with age. 

23 June - Assessing finger-prick antibody tests with key workers

Findings in brief

This study explored the use and performance of finger-prick antibody tests with key workers. The study evaluated the accuracy of the tests by comparing performance with other techniques. The study also looked at how easy they are to perform. 

17 June - Community infection trends in late May and early June

Findings in brief

REACT scientists tested almost 110,000 people between 20th May and 7th June. They found evidence that England's epidemic is growing exponentially, with the prevalence of infection increasing by 50% since the last testing round, from 0.1% to 0.15%. The R number was found to be 1.44. Analysis of positive swabs also found that the majority were the Delta variant first identified in India. 

13 May - Community infection trends in April and early May

Findings in brief

REACT scientists tested over 127,000 people in England between 15th April and 3rd May. They found that since the study's previous report in March, infections had dropped by half to 0.1% of the population, or 1 in 1000 people. The study also successfully analysed the genetic code of a small number of the positive swab samples, finding that the majority were the Kent variant while two, both in London, were the Indian variant of concern. 

7 May - Tracing virus variants in the community from January to March 2021

Findings in brief

REACT scientists looked at coronavirus genetic profiles from swab samples collected between January and March 2021. The majority of infections were with the Kent (B.1.1.7) variant. People infected with this variant were no more likely to report having any of the 'classic four' COVID-19 symptoms, but they were more likely to still have detectable virus antibodies 6 weeks after infection. The study also detected infections with the South African (B.1.351) variant in January, from people who had not travelled internationally, but not February or March. This suggests that this variant was spreading in the community but then faded out over time.

23 April - Community infection trends between May and September 2020 (peer-reviewed publication)

Findings in brief

This peer-reviewed study, published in the journal Science, reports findings from more than half a million swab tests taken between May and September 2020 in England. The researchers found that infections declined between May and July 2020 but then increased gradually from mid-August, accelerating into early September 2020 at the start of the second wave. When compared to COVID-19 cases detected through routine surveillance, the study found a longer period of decline and that infections were clustered in younger age groups.

08 April - Community infection trends in March

Findings in brief

Throughout March, and shortly after the reopening of schools, our study swabbed more than 140,000 people to find out how many people currently have the virus in England, and identify those who have a greater risk of infection. The research found that the rate of new infections levelled off, or plateaued, with 1 in 500 people having the virus (0.2% of the population). This represents approximately a 60% fall since the study's previous findings in February. The study also found that infections are leading to fewer hospital admissions and deaths, which likely reflects the impact of the vaccination programme.

04 March - Community infection trends in February (updated report)

Findings in brief

Our study swabbed more than 163,000 people to find out how many people currently have the virus in England, and identify those who have a greater risk of infection. The study reported that 1 in 204 people are infected, or 0.49% of the population, and that the rate of decline has slowed. The study also found that ethnic minorities, health and care home workers, people working in public transport and those employed in schools, universities, childcare and education all had a higher risk of testing positive. 

02 March - Evaluating finger-prick antibody tests

FIndings in brief

As part of the REACT-2 study, scientists evaluated the accuracy of a number of different finger-prick antibody testing kits to find out if they would be suitable for use in large-scale antibody studies.

25 February - Antibody survey and attitudes towards vaccines

Findings in brief

Our study of 155,000 people has shown that around 14% of England’s population has evidence of antibodies against the coronavirus, either from having had COVID-19 or a coronavirus vaccine. The study also looked at antibody responses in people who have had the Pfizer/BioNTech vaccine, and people's attitudes towards being vaccinated.

18 February - Community infection trends in early February

Findings in brief

The number of people infected with the coronavirus in England has dropped by over two-thirds since January. But infections are still high with around 1 in 200 people testing positive.

10 February - Identifying symptoms linked with COVID-19 

Findings in brief

Our study of over a million people revealed a wide range of additional symptoms that are linked with having the coronavirus. Among these other symptoms, chills, loss of appetite, headache and muscle aches were together most strongly linked with being infected, alongside the four 'classic' symptoms.

28 January - Community infection trends in January 2021

Findings in brief

A very high number of people were infected with the coronavirus in England three weeks into lockdown, with 1 in 64 people testing positive (1.57% of the population). 

21 January - Community infection trends in January 2021 (interim report)

Findings in brief

Coronavirus infections were not falling in the early stages of the third national lockdown in England and 1 in 63 people were testing positive with the virus.

15 December - Community infection trends during England's second national lockdown

Findings in brief

The rate of new coronavirus infections in England was found to no longer be on a downward trend and had flattened in mid-December.

30 November - Community infection trends during England's second national lockdown (interim report)

Findings in brief

Coronavirus infections were found to be declining in England at the end of November, with R below 1. 1 in 100 people were found to test positive. 

12 November - Community infection trends in early November

Findings in brief

Coronavirus infections were continuing to rise in early November but the findings suggested early signs that the rate was slowing down.

29 October - Community infection trends in early November (interim report)

Findings in brief

The infection prevalence was found to have doubled since the previous round of testing, with 96,000 new infections each day.

27 October 2020 - Trends in coronavirus antibodies in England's population

Findings in brief

Tests on more than 365,000 people in England showed that the antibody response to the virus that causes COVID-19 wanes over time.

9 October 2020 - Community infection trends in late September and early October

Findings in brief

An analysis of swab tests taken by 175,000 people between 18th September and 5th October found that the prevalence was rising with the virus infecting around 45,000 people each day.

1 October 2020 - Community infection trends in late September and early October (interim report)

Findings in brief

Infections were found to have increased substantially across all age groups and areas of the country, with 1 in 200 infected. 

11 September 2020 - Community infection trends in August and early September

Findings in brief

The study showed a reversal in coronavirus trends, with infections doubling every 7 to 8 days, compared to May and June when infections were halving every 8 to 9 days

13 August 2020 - Evaluating lateral flow tests in the lab for use in a national coronavirus antibody survey

Findings in brief

An evaluation of a number of different finger-prick antibody testing kits found that the best performing tests are suitable for large-scale surveillance studies to monitor the progress of the pandemic. These could correctly identify individuals with coronavirus antibodies over 80% of the time, while also correctly ruling out those who don’t in more than 98% of tested individuals.

12 August 2020 - Coronavirus antibody prevalence in England following the first peak of the pandemic

Findings in brief

Tests on over 100,000 people showed that slightly under 6% of the population had antibodies to the virus and had likely previously had COVID-19 by the end of June, an estimated 3.4 million people. London had the highest numbers at over twice the national average (13%), while the South West had the lowest (3%).

12 August 2020 - A study to explore how easily people can use antibody self-testing kits at home, and whether these are acceptable to the public 

6 August 2020 - Community infection trends as England exited national lockdown

Findings in brief

The research showed the prevalence of infection decreased to 0.077%, compared to May’s rate of 0.13% despite some lockdown restrictions being eased in June. 

11 July 2020 - Community prevalence of the coronavirus in England during May 2020

Tests on more than 120,000 people carried out between 1 May and 1 June, prior to the easing of lockdown, revealed that infection rates were significantly falling, dropping by half every 8 to 9 days.

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