The number of people infected with the coronavirus in England has fallen by half since the end of March.
These findings from the Imperial College London-led REACT study are based on over 127,000 home swab tests taken between 15th April and 3rd May. The results show that 0.1% of the population is currently infected, or 1 in 1,000. This compares with the study’s previous testing round when 0.2% or 1 in 500 had the virus as of 30th March.
“It is very encouraging that infections have continued to fall while rules have been relaxed in England." Prof Paul Elliott School of Public Health
Looking at data across these two most recent study rounds, the researchers estimate that the reproduction number (R) is 0.90. This means that 10 infected people would pass the virus on to around nine others on average and the epidemic has therefore been shrinking.
The researchers report that since January, the link between the rate of infections, hospitalisations and deaths has become de-coupled, with infections associated with fewer hospitalisations and deaths which likely reflects the impact of the vaccination programme.
The study has also analysed the genetic code of a small number of positive swab samples to look for variants. The majority were found to be the Kent (B.1.1.7) variant. However the study also found the Indian variant of concern in London (B.1.617.2), consistent with a recent report from Public Health England based on analysis of samples taken for routine testing.
Professor Paul Elliott, director of the REACT programme from Imperial’s School of Public Health, said: “It is very encouraging that infections have continued to fall while rules have been relaxed in England, and it’s likely that the vaccine rollout has played a key part in helping keep the virus at bay.
"We need to continue to monitor trends in the coming weeks as restrictions are eased further, and in the meantime, we must continue to stick to the rules to help keep infections down and enable the vaccination programme to continue to protect people.”
These findings from the ongoing REal-time Assessment of Community Transmission (REACT 1) programme, led by Imperial and carried out in partnership with Ipsos MORI, are available here in a pre-print report and will be submitted for peer-review.
Detecting coronavirus variants
For this latest study, 127,408 people across the country took swab tests at home. 115 were positive, giving a weighted infection prevalence of 0.1%. Weighting is when researchers make adjustments in their calculations to ensure that the sample is representative of the wider population.
"It will be important to closely monitor infections and hospitalisations in areas where the variant is present." Prof Steven Riley NIHR Research Professor of Infectious Disease
Of the positive samples, a number have been analysed by genetic sequencing and 26 could be successfully identified. Of those, 24 (92.3%) were the Kent (B.1.1.7) variant and two (7.7%) were the Indian variant of concern (B.1.617.2). Both of the latter were detected in London, in people who did not report international travel within the two weeks prior to testing, suggesting community transmission.
Professor Steven Riley, Professor of Infectious Disease Dynamics at Imperial, said: “The fact that our study detected the Indian variant among a small number of samples could be cause for concern. At the moment it’s unclear whether this variant is more transmissible than B.1.1.7 but this is a risk, so it will be important to closely monitor infections and hospitalisations in areas where this virus is present so that public health responses can be implemented if needed.”
Across the country the number of people infected was found to be fairly similar, ranging from 0.07% in the South West to 0.13% in the West Midlands.
"We’re going in the right direction but with variants present, we must continue to exercise caution." Matt Hancock Health Secretary
Compared to the previous study round, infections have fallen across all age groups except 25-34-year-olds which had the highest prevalence (0.21%), but with a wide range of uncertainty. In people aged 55-64 years, infections fell substantially by almost two-thirds, from 0.17% to 0.06%, which may be due to the effect of vaccination in this age group. The lowest prevalence was found in people over the age of 75 at 0.05%.
Health and Social Care Secretary Matt Hancock said: “Today’s findings demonstrate the impact our incredible vaccination rollout is having on COVID-19 infection rates across the country, with prevalence lowest amongst those more vulnerable people aged 65 and over.
“We will continue to monitor the data closely as we cautiously enter stage three of our roadmap on Monday. We’re going in the right direction but with variants present, we must continue to exercise caution and follow hands, face, space and fresh air, and get the jab when the offer comes.”
Understanding levels of infection in the community
The REACT 1 study is tracking current coronavirus infections in the community by testing more than 125,000 randomly-selected people each month over roughly a two-week period. The study recruits new people each month to help ensure the sample represents the wider population and offers a high-resolution snapshot of the situation across a particular time period.
This is different from the ONS COVID-19 Infection Survey which runs continuously and samples the same people over time to understand household transmission. Because the studies use different methods, this means that sometimes they report different figures.
Kelly Beaver, Managing Director, Public Affairs at Ipsos MORI said: “The further reduction in COVID-19 prevalence is incredibly encouraging. Many thanks to the 1.7 million people who have taken part in the REACT1 study as volunteers to date – their contribution is helping us understand the prevalence of COVID across England as we continue on the government’s roadmap milestones.”
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