Coronavirus infections in England may no longer be declining at the rapid rate seen in early January, according to new swab testing data.
[This article was updated on 26 January]
Findings from the ongoing REACT coronavirus monitoring programme, based on over 100,500 swab tests taken between 5 and 20 January, show that around 1 in 23 was infected during this period, or 4.41% of people. This is the highest the study has recorded since it began testing in May 2020, and more than three times higher than the study’s previous findings in December, when 1 in 70 had the virus (1.40%).
Trends in the data suggest that infections rose sharply between these two study periods, reaching a peak estimated at around 5 January, and then fell before flattening off at a very high rate by mid-January.
"Of particular concern is that there is rapidly increasing prevalence among children now they are back at school." Prof Paul Elliott School of Public Health, Imperial
In the most recent data, trends varied by age with infections decreasing in adults (R below 1) but rising in school-aged children (R over 1). 5-11-year-olds had the highest number of infections with 1 in 13 testing positive (7.81%), while those aged 75+ had the lowest at 1 in 41 (2.43%). However in the latter age group, this figure represents a near 12-fold increase compared to December.
Of those who reported whether they had a history of COVID-19, almost two-thirds (64.6%) of infections were in people who reported confirmed prior COVID-19. However these results are based on self-reported data and therefore it’s uncertain what proportion of these are reinfections or recent infections picked up due to the sensitivity of PCR testing.
Professor Paul Elliott, director of the REACT programme from Imperial’s School of Public Health, said: “There is good news in our data in that infections had been rapidly dropping during January, but they are still extremely high and may have recently stalled at a very high prevalence.
“Of particular concern is that there is rapidly increasing prevalence among children now they are back at school and, compared with December, prevalence in older people aged 65+ has increased seven- to 12-fold, which may lead to increased hospitalisations.
“It’s therefore vital that we continue to monitor the situation closely to understand the impact of the Omicron variant, which now makes up almost all infections in the country.”
These findings from the REal-time Assessment of Community Transmission (REACT-1) programme, led by Imperial College London with Ipsos MORI and commissioned by the Department of Health and Social Care, are available here in a pre-print report and will be submitted for peer-review. Data are continually reported to the Government to inform decision-making.
Regional and demographic variation
For this latest round of the REACT study, 100,607 people swabbed themselves at home and their samples were analysed by PCR testing. 4,011 of these were positive, giving an overall weighted prevalence of 4.41%. Weighting is where the researchers make adjustments to their calculations to ensure the sample reflects England’s population.
Out of 1,816 positive samples analysed, scientists were able to successfully trace the genetic roots of 1,406, almost all of which were the Omicron variant (99%), and six were the BA.2 variant under investigation. The remaining 1% were Delta.
For the entire study period, the R number was estimated to be 0.95, meaning 100 infected people would on average pass the virus on to 95 people, therefore the overall number of infections is shrinking.
For those aged 17 and under, R was estimated to be 1.13. While for adults, R was estimated to be 0.85 in 18-54-year-olds, and 0.89 for those aged 55 and above.
Compared to the previous testing round in December, infections rose in all age groups and areas of the country. However in the most recent data, infections fell in the North West and Yorkshire and The Humber. The highest infection prevalence was found in the North East at 6.85%, up from 1% in December, while the lowest was found in the South West at 2.93%, up from 1.57%.
Among those who reported whether they had a history of COVID-19, the weighted prevalence of infection was also found to be substantially higher in those who reported previous confirmed COVID-19 (14.1% or 1 in 7) compared to those with no past history of the virus (1.75% or 1 in 57). As these results are based on self-reported data, it’s uncertain what proportion of these are reinfections or recent infections picked up due to the sensitivity of PCR testing.
Links between infections, hospitalisations and deaths
The researchers also looked at existing, publicly available data on COVID-19 hospitalisations and deaths and compared these with the REACT data on infection rates. They found that between February and May and September and December of 2021, there was a reduced risk of hospitalisation, and between February and December inclusive there was a consistently lower risk of death. This is likely due to the impact of the vaccination programme and improved treatment.
"The impact the vaccination is having on preventing severe disease and hospitalisations is clear to see." Dr Jenny Harries CEO, UK Health Security Agency
Dr Jenny Harries, Chief Executive of the UK Health Security Agency, said: “The latest round of REACT data reiterates that while case rates have slowed recently, prevalence is still high. Vaccination remains the best way to protect yourself from severe disease and hospitalisation from Omicron, and I would urge anyone who has not done so to come forward for their first, second and third doses as soon as possible. The impact the vaccination is having on preventing severe disease and hospitalisations is clear to see.
“To ensure we continue on the downward trend and protect our communities, it is still important for us all to follow public health advice, including wearing masks in indoor settings. If you are visiting friends and family, make sure to take a test before going out.”
"As we learn to live with the virus it is vital we continue to be vigilant." Sajid Javid Health and Social Care Secretary
Health and Social Care Secretary Sajid Javid said: “It’s reassuring to see COVID-19 infections beginning to slow across the country, as we move back to Plan A.
“COVID-19 rates are still high so as we learn to live with the virus it is vital we continue to be vigilant – wash your hands, let in fresh air, get tested and, if you haven’t already, Get Boosted Now.”
Kelly Beaver, CEO at Ipsos MORI, said: “The large increase in infections associated with the extraordinarily rapid rise of the Omicron variant highlights the need to continue following the public health advice. But the in round decline in prevalence is encouraging and everyone should get vaccinated when able to.
“Surveillance studies like REACT continue to be critical to monitoring the virus within the community, so thank you to the over 2.3 million people who have now participated since the study’s inception.”
Access the preprint report here, Post-peak dynamics of a national Omicron SARS-CoV-2 epidemic during January 2022
This article was updated on 26 January to include self-reported data on infection history.
Article text (excluding photos or graphics) © Imperial College London.
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