Delta mutation is no reason to panic, scientists say

LONDON — A recently discovered subvariant of Covid-19’s delta strain now makes up 10% of new U.K. cases — but scientists have said there’s no reason to panic.

Known as AY.4.2, there are some concerns that it could be around 10% more transmissible than the original delta strain, but there is so far insufficient evidence to prove that this is the case.

The subvariant — which is thought to have emerged in the U.K. over the summer — has two additional mutations affecting its spike protein, part of the virus’s structure used to infiltrate cells. Questions are still hanging over exactly how, or if, those mutations will affect how quickly it spreads.

In the last 28 days, AY.4.2 has accounted for around 10% of new Covid-19 cases, according to data from public health consortium Cog-UK. That makes it the U.K.’s third most dominant version of Covid-19 for the past four weeks after the original delta strain and another of its so-called sublineages.

Despite its rise, public health officials in England have emphasized that so far, AY.4.2 does not appear to cause more severe disease or render existing vaccines less effective. And according to biologists at England’s Northumbria University, the mutation has failed to take hold in several European countries, “dropping off the radar in Germany and Ireland.”

Christina Pagel, director of the Clinical Operational Research Unit at University College London, told CNBC via telephone that although delta’s new subvariant was definitely growing in the U.K. and elsewhere, it was not a huge cause for alarm.

“It looks like it has somewhere between a 12% and 18% transmission advantage over delta, so it’s not good news in that sense. It’s going to make things a bit more difficult, but it’s not a massive jump,” Pagel said.

“Delta compared to alpha was around 60% more transmissible, it was doubling every week. This is going up by a percent or two a week — it’s much, much slower. So in that sense, it’s not a big disaster like delta was. It will probably gradually replace delta over the next few months. But there’s no sign it’s more vaccine resistant, [so] at the moment I wouldn’t be panicking about it.”

However, the emergence of the new mutation did raise some concerns, Pagel said. If the new mutation arrived in countries that were further behind the U.K. in their vaccination programs, it would create additional problems, she added. It also proved the coronavirus is still mutating.

“There are lots of different subtypes of delta, [but] this is the first subtype that seems to actually have an advantage over the other deltas,” Pagel said. “And it just shows that there’s more places for it to go and evolve to. Some people have been saying delta’s hit the sweet spot – well look, it’s found another sweet spot.”

Pagel called for some mitigation measures…