SARS-CoV-2 infections in England have risen to a record high, new preliminary surveillance data showed.
Based on swab samples taken from 109,459 people aged 5 and older between March 8 and March 31, around 1 in 16 tested positive for COVID-19, or 6.37% of those sampled.
Scientists at Imperial College London (ICL) said the results from the latest round of the REal-time Assessment of Community Transmission-1 (REACT-1) study suggested that prevalence was more than double that of the study's previous findings when 1 in 35 tested positive, as of March 1, or 2.88%.
Infections had risen in all age groups and remained highest among primary school children, with 8.81% of 5- to 11-year-olds testing positive.
Concern Over Future Hospitalisation Numbers
However, although the most recent trends suggested that the rate of new infections could be slowing in those aged between 5 and 54, infections could still be rising among older people, which "may increase hospitalisations and deaths, despite high levels of vaccination", the study concluded.
The data from round 19, published as a preprint, suggested that COVID prevalence at the end of last month was at its highest since the study began in May 2020, and 40% higher than the first peak of the Omicron variant in January this year.
The BA.1 subvariant of Omicron had been almost completely replaced by the more transmissible BA.2, scientists said. Compared to BA.1, the BA.2 Omicron sub-lineage appeared to have a growth rate advantage of 0.11. Viral genome sequencing showed the proportion of lineages from those tested were 99.97% Omicron, of which 10.2% were BA.1, 89.7% BA.2 and 0.03% BA.3 sub-lineages. The remaining 0.03% of positive samples was Delta AY.4.
The analysis also detected a small number of cases of recombinant variants of the original BA.1 Omicron strain and BA.2. There were 5 cases of XE and three of XL.
On March 25, the UK Health Security Agency (UKHSA) reported 637 cases of XE in England, with the earliest case identified on January 19. Using the most recent data up to mid-March XE appeared to have a growth rate 9.8% above that of BA.2, the UKHSA said in a technical briefing.
However, ICL scientists said because of the small number of recombinants in their sample, it was not possible to determine whether the variants were more transmissible than others.
'Concerning' Trends as Study Loses Funding
Prof Paul Elliott, director of the REACT programme, said: "These trends are concerning since when a very high number of people are infected, this may lead to more people becoming seriously ill and needing to go to hospital.
Dame Jenny Harries, chief executive of the UKHSA, said: "These latest study results are another reminder that the pandemic is not over, and there is still a real risk to many of us catching COVID-19 with infection rates so high."
Round-19 was the final report of the REACT-1 study following the Government's decision to withdraw funding. Other research into COVID-19 prevalence, including the ZOE COVID study also lost its funding.
The preliminary results from round 19 of REACT-1 are being submitted for peer-review.
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