Research uncovers accelerating spread of infection from late August to early September
Iran Press TV
Friday, 11 September 2020 4:09 PM
The study, known as React-1, began in May using swabs from about 120,000 to 160,000 randomly selected people across 315 local authority areas each month to track the spread of coronavirus using PCR analysis – the "have you got it now" test, has revealed a doubling every week of cases in England, suggesting a resurgence of COVID-19.
The study is a population surveillance study, which involves identifying all new cases of the disease under surveillance in a defined population. The data obtained can be used to calculate the disease incidence rate since the size of the population under surveillance is known.
"The prevalence of the virus in the population is increasing. We found evidence that it has been accelerating at the end of August and beginning of September," said Steven Riley, professor of infectious disease dynamics at Imperial College London and a co-author of the work.
These finding came as the latest R figure for the UK was reported to be between 1.0 and 1.2 with the number of infection fluctuating between decreasing by 1% and increasing by 3% every day.
Previous rounds of the study revealed a falling prevalence of COVID-19, even as lockdown restrictions were eased: according to data for the period 19 June to 8 July, the prevalence of COVID-19 in the general population was low, halving every eight to nine days.
Results from the fourth round of the survey, however, imply that this no longer holds true. Although the latest findings for the React study have still to be peer-reviewed, researchers say swabs collected between 22 August and 7 September from more than 150,000 people revealed 136 positive tests, suggesting 13 people per 10,000 in the general population were infected with Covid-19.
Despite the prevalence being far lower than it was in March and April, researchers note, it is higher than it was between 19 June and 8 July and between 24 July and 11 August.
According to results collated, cases are rising in almost all regions, but it is more pronounced in some areas than others, with Yorkshire and the Humber, the north-west and north-east showing the highest prevalence of Covid-19.
"It is happening everywhere but it is happening more in some places than others," said Prof Paul Elliott, the director of the React programme and chair in epidemiology and public health medicine at Imperial College London.
Professor Riley agreed. "There is a difference in the starting level and there is a difference in the speed [in different areas]," he said. "But I think the overall trend of moving into growth does seem to be affecting a really large proportion of England."
The survey data between 22 August and 7 September suggests prevalence is doubling every 7.7 days, with the R value for England estimated to be 1.7. At the start of lockdown prevalence was doubling about every three to four days. In addition, the cases are no longer primarily found in clusters in care home and hospital settings, but are spreading more widely in the community.
The researchers, amid other findings, found that almost two-thirds of those who tested positive for Covid-19 had no symptoms either at the time the swab was taken, or in the seven days before.
Although figures show the rates are at present highest among 18-24-year-olds, with a marked increase from the previous round, the team says rises have been recorded across many age groups, including children aged five to 12.
"All the way up to 65 years old, amongst adults the prevalence has been increasing, so it is not just happening in the younger people," said Elliott, adding over-65s might be continuing to shield.
The results clearly show that prevalence was also higher among minority ethnic groups compared to the rest of the population.
Matt Hancock, the health and social care secretary, warned the pandemic was not over yet. He said: "It's so important that everyone abides by the law and socialises in groups up to six. Make space between you and those outside your household, get a test and self-isolate if you develop symptoms and wash your hands regularly. It is vital you engage with the NHS test and trace service if contacted to provide details of your close contacts and self-isolate if you are asked to do so."
Dr Zania Stamataki, a viral immunologist at the University of Birmingham, agreed. "This detailed study clearly shows how valuable it is for us to continue to monitor infections using testing, and how contact tracing can actually help identify other infected people for isolation even in the absence of symptoms," she said.
"There is a real risk that the surge in cases, even amongst the young, will soon translate to increased hospitalisations of the vulnerable."
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