The prevalence of Covid in the UK has fallen overall in recent weeks, but has risen in school-age children, researchers say who have warned the rise could pose a risk to adults.

The latest data from the React-1 study, which is based on over 100,000 swabs from randomly selected individuals in England collected between January 5 and 20 this year, shows that the weighted overall prevalence of Covid was 4.41%, with 99% positive tests involving the Omicron variant.

The team notes that the overall prevalence is more than three times higher than the previous round in December 2021.

“[It] is by far the highest we have seen throughout the pandemic,” said Professor Paul Elliott of Imperial College London, who led the study.

The team adds that among people aged 75 and over, the prevalence increased almost 12-fold between cycles, but Elliott noted that the prevalence was highest in the last cycle of the study among children. aged 5 to 11, at 7.81%.

While the team adds that in January the overall prevalence was found to be falling, in children aged 5 to 17 it increased. This, they write, is “probably the consequence of the peak occurring during the end-of-year school holidays, causing a delay in transmission in school settings in children”, noting that the increase could pose a risk for adults. .

“There is clearly a risk of transmission from children to adults, although currently adult rates are decreasing,” Elliott said.

The study also reveals that around two-thirds of those who tested positive in the last cycle said they had already had a confirmed Covid infection – although Elliott noted that this could have been at any time during the pandemic, which means that not all of them can be true reinfections. However, the team says the finding suggests that certain groups have a higher risk of being exposed to the coronavirus.

While researchers say vaccination remains the mainstay of defense against Covid, especially given the protection it offers against hospitalization, other approaches may be needed.

“Additional measures beyond vaccination may be required if very high rates of Omicron infection persist, although Omicron appears to be inherently less likely to cause severe disease,” they write.