The World Health Organization (WHO) has issued a warning over the increased spread of the BA.4 and BA.5 COVID variants after cases rose in 110 countries.
Global coronavirus infections have increased by 20% and deaths have risen in half of the six WHO regions, the organisation's director-general Dr Tedros Adhanom Ghebreyesus said.
During a media briefing on Wednesday, he warned the pandemic was “not over”, cautioning that decreased testing and sequencing meant it was getting harder to track new variants.
BA.4 and BA.5, both Omicron subvariants, were classified by the UK Health Security Agency (UKHSA) as “variants of concern” on 20 May after analysis found both were likely to have a “growth advantage” over BA.2, the current dominant variant.
Dr Tedros said: “Our ability to track the COVID-19 virus is under threat as reporting and genomic sequences are declining meaning it is becoming harder to track Omicron and analyse future emerging variants.”
Meanwhile, infections in all four nations of the UK are rising, with the spike driven by BA.4 and BA.5, which now make up more than half of all new COVID-19 cases in England.
The BA.5 variant is thought to be growing approximately 35% faster than BA.2, while BA.4 is growing 19% faster – meaning it is likely that BA.5 will soon become the dominant COVID-19 variant.
There is “currently no evidence” that the two variants cause more serious illness than previous variants, according to early research from the UKHSA.
Infection levels in England are back to where they were at the end of April.
Figures published last week by the Office for National Statistics showed an estimated 1.7 million people in private households in the UK had COVID in the week to 18 June, up 23% from 1.4 million a week earlier.
The number of people in hospital in England who have tested positive for COVID-19 is also continuing to increase, in further evidence of the growing prevalence of the virus.
NHS figures show 7,822 patients in England had the virus on 27 June, up 37% on the previous week.
It is the highest total for nearly two months, but still well below the peak of 16,600 patients during the Omicron BA.2 wave.
UKHSA chief medical adviser Professor Susan Hopkins said: “It is clear that the increasing prevalence of Omicron BA.4 and BA.5 are significantly increasing the case numbers we have observed in recent weeks.”
In Scotland, 948 patients were recorded on 19 June, the latest date available, up 27% from the previous week.
The trend in Northern Ireland is uncertain, with numbers rising in early June before levelling off in recent days between 320 and 340.
In Wales, 417 hospital patients with COVID-19 were recorded on 24 June, up 41% from the previous week.
Infections in Wales have climbed to levels last seen in early May.