Coronavirus infections levelling off in England - REACT study


A coronavirus testing kit

The rate of new coronavirus infections has levelled off with 1 in 500 people currently infected in England.

These latest findings from the Imperial College London-led REACT study are based on at-home swab tests taken by almost 141,000 people between 11th and 30th March.

The results show that 0.2% of England’s population has the virus, a fall of approximately 60% compared with the study’s previous findings in February, when 0.49% of people were infected (1 in 204).

"This is hugely encouraging and shows we’re headed in the right direction. But we need to continue to approach the situation with caution." Prof Paul Elliott School of Public Health

Primary school-aged children (aged 5-12) had the highest number of infections at 0.41%, while those aged 65 and above had the lowest at 0.09%. These trends are likely due to a combination of factors including schools reopening and the COVID-19 vaccination programme.

The researchers also estimated that the reproduction number (R) is 1.0, which means the epidemic is neither growing nor shrinking as each infected person infects one other individual, on average.

Professor Paul Elliott, director of the REACT programme from Imperial’s School of Public Health, said: “We have seen a gratifying fall in infections since our last survey in February, with infections dropping by around 60% overall. This is hugely encouraging and shows we’re headed in the right direction.

“However, in our most recent data there has been a flattening off in the infection rate with an R number now around one. This shows that we need to continue to approach the situation with caution and keep sticking to the rules.”

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.

The latest coronavirus trends

For this latest study, 140,844 people across the country took swab tests. Of these, 227 were positive, giving a weighted infection prevalence of 0.20%. Weighting is when researchers make adjustments in their calculations to ensure that the sample is representative of the wider population.

"With the country continuing to open up in the coming weeks, we would expect prevalence of infections to rise." Prof Steven Riley School of Public Health

Looking at trends since the previous round of testing, which ran from 4th to 23rd February, infections have been falling by half every 26 days. However the rate of decline has slowed across this period and has now flattened, or plateaued.

Professor Steven Riley, Professor of Infectious Disease Dynamics at Imperial, said: “Our results are consistent with patterns observed in other data such as cases and hospitalisations and are supportive of a gradual easing of restrictions. But with the country continuing to open up in the coming weeks, we would expect prevalence of infections to rise. Future rounds will allow us to monitor the situation closely.”

Compared with February’s data, there have been substantial falls in different parts of the country, from 0.36% to 0.07% in the South East; 0.60% to 0.16% in London; 0.47% to 0.15% in the East of England; 0.59% to 0.19% in the East Midlands; and 0.69% to 0.31% in the North West.

The researchers also looked at how the link between infections, deaths and hospitalisations has changed across previous study rounds. They found that infections are now leading to fewer hospital admissions and deaths, which likely reflects the impact of the vaccination programme.

Understanding levels of infection in the community

The REACT 1 study is tracking current coronavirus infections in the community by testing more than 140,000 randomly-selected people each month over 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: “Over 1.5 million people in England have now participated in the REACT study and the data from this round is very encouraging, with a 60% reduction in prevalence since the last round in March.

“But as we progress through the roadmap out of lockdown, we must remain vigilant. The R number being at 1 means we need to remain cautious in our approach over the coming weeks and months.”

Download the report here.


Justine Alford

Justine Alford
Institute of Global Health Innovation

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