Largest COVID-19 testing study shows cases are rising across England


COVID-19 swab test

Latest findings from the biggest programme of home coronavirus testing in England have revealed that cases are growing in the community.

Results from swab tests carried out by over 150,000 people between mid August and the start of September show a recent reversal in trends, with infections doubling every 7 to 8 days, compared to May and June when infections were halving every 8 to 9 days. 

The research, led by Imperial College London, estimated the reproduction number (R) at the end of August and beginning of September to be 1.7, and that 13 people per 10,000 were infected with the virus (an estimated 0.13% of the population). 

In contrast to previous patterns of infection, cases were not found to be clustering in healthcare or care home workers, suggesting transmission is happening outside these settings. And although infections are increasing across all areas of the country and adult age groups below the age of 65 and, higher rates were seen in young people aged 18-24 and regions in the North of England. 

These findings from the REal-time Assessment of Community Transmission (REACT 1) programme are available in a pre-print report and will be submitted for peer-review. 

"This is a critical time and it’s vital that the public, our health system and policy-makers are aware of the situation as we cannot afford complacency." Professor Paul Elliott Chair in Epidemiology and Public Health Medicine, School of Public Health

Professor Paul Elliott, Director of the programme at Imperial from the School of Public Health, said: “Our large and robust dataset clearly shows a concerning trend in coronavirus infections, where cases are growing quickly across England and are no longer concentrated in key workers. What we are seeing is evidence of an epidemic in the community and not a result of increased testing capacity. This is a critical time and it’s vital that the public, our health system and policy-makers are aware of the situation as we cannot afford complacency.”

The REACT programme, the biggest of its kind, is a series of studies that are monitoring how the virus is spreading across the country. Commissioned by the Department of Health and Social Care, it is being carried out in partnership with Ipsos MORI and Imperial College Healthcare NHS Trust.

Community coronavirus transmission

For this phase of the programme, nose and throat swabs from more than 161,000 people over the age of 5 were taken between 24th July and 11th August. This was followed by a further 153,000 taken between 22nd August and 7th September. Participants were randomly chosen to ensure a nationally-representative sample. Samples were analysed in the laboratory for the presence of the coronavirus, using a test called PCR. Participants also filled in a questionnaire that gathered information on age, sex, ethnicity, key worker status, demographics, living situation and symptoms.

In the first batch of tests, 54 swabs came back positive and cases were doubling every 14.2 days. Based on this number the researchers estimated the prevalence for this period to be 0.04%. In the most recent round 136 people tested positive, giving an overall estimated prevalence of 0.13%. Across the whole study period, R was estimated to be 1.3. 

Increases in prevalence were observed country-wide but patterns were not even. The North West (0.17%), North East (0.16%) and Yorkshire and the Humber (0.17%) had the highest rates of prevalence and growth. 

The virus was also found to be continuing to disproportionately affect ethnic minorities. In the most recent round of testing, Black and Asian people were more than twice as likely as white people to test positive (0.2% prevalence vs 0.08%). 

Young people aged 18-24 were also significantly more likely to be infected than all other age groups (0.25% prevalence, up from 0.08% between 24th July and 11th August), while the lowest rates were found in those aged 65 and above (0.04%). 

Health and Social Care Secretary Matt Hancock said: "We’ve seen all across the world how a rise in cases, initially among younger people, leads to hospitalisations and fatalities. The pandemic is not over, and everyone has a role to play to keep the virus at bay and avoid any other further restrictions.

“You must abide by the law and socialise in groups up to six, make space between you and those outside your household, wear a face covering over your nose and mouth in enclosed spaces, get a test and self-isolate if you develop symptoms and wash your hands regularly. It is vital you engage with NHS Test and Trace service if contacted to provide details of your close contacts and self-isolate if you are asked to do so."

Tracking the evolving pandemic

The REACT 1 study is continuing to monitor the situation in England and will soon launch the next round of nation-wide testing, which will involve a further 150,000 randomly-selected individuals. 

Professor Steven Riley, study author and Professor of Infectious Disease Dynamics at Imperial, said: “From our data we are observing evidence of a resurgence in coronavirus cases in the community during July and August, with a notable increase in R in the second week of August. We don’t know if those recent high levels of transmission will be maintained. The next round of testing as part of our programme will be critical to understand this and guide appropriate public health measures. None of this would be possible without the involvement of hundreds of thousands of members of the public, whose ongoing contributions are enabling this essential research.” 

A separate arm of the programme, REACT 2, is using antibody finger-prick tests to monitor past infections across England. The results of the first 100,000 people tested have already been announced and findings from the next round, involving another 100,000 people, are expected soon.

Kelly Beaver, Managing Director- Public Affairs at Ipsos MORI said:

“Each and every participant in our study has contributed immensely to the national effort in tracking COVID-19 across England. I would like to thank all those who have taken part for their invaluable contribution. By participating in the study they have helped to provide timely data to Government on the rise in case numbers and allowed Ministers to adopt measures to combat that rise.”

Read the pre-print paper in full here.


Justine Alford

Justine Alford
Institute of Global Health Innovation

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