A new Covid variant has been found to be dominant in the UK as it causes widespread waves of infection across the globe.
Omicron BA.5 is now the dominant Covid strain, accounting for approximately 79% of UK cases as of 18 July.
Omicron BA.2.75 has been categorised as a separate variant to other BA.2 variants, but not as a Variant of Concern.
The latest UK Health Security Agency (UKHSA) Covid 19 variant technical briefing, published today, confirms an estimated 78.7% of confirmed cases in England are BA.5 which was first identified in April and was designated as a Variant of Concern on 18 May.
Dr Meera Chand, UKHSA Director of Clinical an Emerging Infection, said:“We continue to monitor the emergence of new variants and give them variant designations if they are sufficiently distinct to warrant separate epidemiological and laboratory assessment.
"It is not unexpected to see new lineages and continued investigation is a normal part of the surveillance of an infectious disease. It is important that everyone ensures that they are up to date with all vaccinations that have been offered as they remain our best form of defence against severe illness.”
It comes as around 3.8m people - one in 17 of the UK population - has coronavirus, latest figures from the Office for National Statistics suggest.
The number of people testing positive across the UK has been rising since the start of June but the rate of rise is showing signs of slowing down.
In the latest report, for the week ending 13 July, the ONS estimates Covid rates were:
- One in 17 in England - up from one in 19 the week before
- One in 17 in Wales - the same as the previous week
- One in 20 in Northern Ireland - down from one in 17
- One in 15 in Scotland - up from one in 16
However, BA.5 is not new. First identified in January, it has been tracked by the WHO since April.
It is a sister variant of the Omicron strain that has been dominant worldwide since the end of 2021, and has already caused spikes in case rates – even with reduced testing – in countries including South Africa, where it was first found, as well as the United Kingdom, parts of Europe, and Australia.
Coronavirus cases worldwide have now been rising for four weeks in a row, WHO data showed.
Why is Covid spread?
Like its closely related sibling, BA.4, BA.5 is particularly good at evading the immune protection afforded either by vaccination or prior infection.
For this reason, "BA.5 has a growth advantage over the other sublineages of Omicron that are circulating," Maria Van Kerkhove, the WHO's technical lead on COVID-19, told a news briefing on Tuesday.
For many people, this means that they are getting re-infected, often even a short time after having COVID-19. Van Kerkhove said the WHO is assessing reports of re-infections.
"We have ample evidence that people who've been infected with Omicron are getting infected with BA.5. No question about it," said Gregory Poland, a virologist and vaccine researcher with the Mayo Clinic in Rochester, Minnesota.
If that seems particularly common now, it could be simply because so many people got Omicron, researchers have suggested.
