A rise in COVID infections could spark a new wave of "mass sickness" leading to large numbers being off work, an expert has suggested.
The most recent figures from the Office for National Statistics (ONS) show that a total of 989,800 people in private households in the UK are estimated to have had the virus in the week ending 2 June, up from 953,900 the previous week.
It is the first time total infections have risen week-on-week since the end of March, when the number of people with COVID hit a record 4.9 million at the peak of the Omicron BA.2 wave.
The rise is likely to have been caused by a jump in infections compatible with the original Omicron variant BA.1, along with the newer variants BA.4 and BA.5, according to the ONS.
Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, has now suggested that there could be “waves of people feeling unwell” if infections continue to go up.
While accepting it was too early to tell what impact a rise in infections will have on hospital admissions, Clarke added: “There will be more infections, I would expect that there would be waves of people being unwell, sort of mass sickness.
"And there may be an increase in people ending up in hospital."
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Omicron BA.1 is the original variant of Omicron that caused a surge in infections across the UK in December and early January.
BA.4 and BA.5 are newer variants that were recently classified by the UK Health Security Agency (UKHSA) as “variants of concern”, after analysis found both were likely to have a “growth advantage” over BA.2, which is still the dominant strain in the country.
Initial findings suggest BA.4 and BA.5 have a degree of “immune escape”, meaning the immune system can no longer recognise or fight a virus, which is likely to contribute to their growth advantage over BA.2, the UKHSA said.
All four nations in the UK have seen a slight rise in the prevalence of coronavirus.
In England, 797,500 people were likely to test positive for COVID last week – the equivalent of about one in 70. This is up week on week from 784,100, which was also about one in 70.
Northern Ireland saw a rise to 27,700 people (about one in 65), up from 24,300 (about one in 75) from the previous week.
Meanwhile in Scotland 124,100 (one in 40) people were likely to have had the virus last week, up from 105,900 (one in 50).
Wales has seen COVID infections increase very slightly to an estimated 40,500 people, up from 39,600, both equivalent to about one in 75.
The latest estimates for COVID infections come as separate figures show the recent fall in the number of people in hospital with the virus may have come to a stop.
Some 4,082 patients in England had COVID on 9 June, up 6% on the previous week, while in Scotland 637 patients were recorded on 5 June, the latest date available, up 8% week on week.
However, patient numbers across the UK remain well below the peaks reached during previous waves of the virus.