A new sub-variant of Delta Covid that now accounts for 12% of UK cases may be less likely to cause symptomatic disease, scientists have found.
The mutation — known as AY.4.2. or Delta Plus – first emerged in the country over the summer and a study published last week found its prevalence has doubled in the last two months.
But, although the subvariant may be 10 to 15% more infectious, it was found to cause fewer symptomatic cases than its Delta parent, AY.4.
Cases in the UK are on the rise once again, with more than 40,000 new positive tests results reported yesterday.
Ministers have played down the need to introduce more measures to reduce the spread of infection, despite worrying cases rises in much of the rest of Europe.
Delta, first identified in India, has now become by far the most dominant Covid strain across the world and now accounts for 99.5% of all cases, according to the World Health Organisation.
Scientists are still fearful that a new, even more damaging, variant may still emerge but are cautiously optimistic that the AY.4.2. can be successfully contained.
Ravi Gupta, professor of clinical microbiology at the University of Cambridge told the Observer the new variant was ‘relatively wimpy’ compared to the threat of a totally new Covid strain to replace Delta.
He said: ‘We’ve got a Delta pandemic at the moment. This new Delta Plus variant is relatively wimpy compared to the kind of thing I’m talking about.
‘It has two mutations from the Delta strain, I don’t think they are that worrisome and it hasn’t taken off in a big way in other countries. But it’s inevitable that there will be another significant variant in the next two years and it will compete with Delta and it may out-compete Delta.’
Imperial College London and Ipsos MORI’s REACT study found last week that AY.4.2. made up 12% of all new cases of the virus between October 19 and November 5.
Two-thirds of those infected with AY.4.2. reported experiencing ‘any symptom,’ compared to more than 75% of those who have the more dominant AY.4 strain.
Just a third of those with AY.4.2. had ‘classic Covid-19 symptoms’ such as a cough, a temperature or loss of taste or smell. This compared to almost half of the people with AY.4.
Scientists are still studying why this may be the case – it could simply be that cases have so far been confined to the young who are less likely to get sick from Covid anyway.
The lack of symptoms may also explain why it appears more transmissible, with people con
Professor Paul Elliott of Imperial said: ‘We’re not sure why AY.4.2 might be associated with less symptomatic infection, but that might give it a transmission advantage as people carrying AY.4.2. are less likely to know that (as more of them will be asymptomatic).’
Politicians and scientists are hopeful that the UK can avoid a similar rise in cases to that being seen currently in Europe.
Case numbers have been high but steady in the country all summer, while the vaccination campaign has also been more successful than in some of the UK’s neighbours.
This, it is hoped, will provide a greater level of protection against a surge in cases as winter begins.
Professor Peter Openshaw, a member of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), told BBC Breakfast: ‘The situation appears to have really been destabilised in some parts of Europe because of misinformation, particularly about vaccines.
‘I think, in the UK, we had a very successful early vaccination campaign and we got very high vaccination rates, particularly amongst those who are vulnerable, but obviously that means that many people have now been vaccinated some time ago and they do need the boosters in order to raise their level of immunity back up again and make sure that, as we go into the winter season and towards Christmas, that we have very high levels of immunity again within society.’
Get in touch with our news team by emailing us at firstname.lastname@example.org.
For more stories like this, check our news page.