Delta plus AY.4.2: Australia being vigilant of new Delta mutation surging through Britain

Australia is being “vigilant” about a new mutation of Delta which is thought to be more transmissible and could be partly to blame for a new surge.

There are growing calls for more focus on a so-called “Delta plus” Covid-19 variant with fears it could be a least partially responsible for the UK’s surging number of new cases.

Australia’s chief medical officer Professor Paul Kelly said on Wednesday that “close vigilance” was being kept on the mutation.

Earlier this week, a former senior US official said “urgent research” was needed into Delta variant AY.4.2 which now accounts for almost one in 10 of new British cases.

For the past week the UK has recorded more than 40,000 new daily infections of Covid-19 despite relatively high vaccination rates.

Deaths from Covid are running at about 800 a week in the UK. It sounds like a big number but it’s far lower than earlier in 2021 when vaccines weren’t available.

A spokesman for UK Prime Minister Boris Johnson said: “We’re monitoring it closely and won’t hesitate to take action if necessary.”

A report for the UK Health Security Agency said Delta plus was “noted to be expanding in England” adding that it was being monitored.

Covid cases in the UK have surged to 40,000 a day. Picture: Rob Pinney/Getty Images

Delta plus spreading in Europe, US and now Israel

Delta plus has also now been detected in Israel, US and Denmark. On Tuesday, Israeli authorities said its first case of Delta plus had been found in an 11 year old boy who had returned from Moldova from Eastern Europe.

NSW Health told news.com.au no cases of AY.4.2 had been detected in international travellers in the last month passing through Sydney Airport – Australia’s busiest gateway.

Speaking yesterday in Canberra, Prof Kelly noted Delta plus but sought to calm concerns over it.

“We continue to have close vigilance of the international situation to see what the experience may come from this virus; to watch out for what next variant may come from this virus.

“(But) to be clear, (Delta plus) is not a ‘variant of interest’ or a ‘variant of concern’ at the moment.”

Variants of interest and concern are two categories designated by the World Health Organisation. The former is variants which have genetic changes that have the potential to cause increased transmissibility or illness; the latter are variants that have been proven to do just that.

(L-R) Greg Hunt with chief medical officer Professor Paul Kelly who said Australia was being vigilant about overseas Covid developments including Delta plus. Picture: Gary Ramage/NCA NewsWire

It’s only the latest ‘Delta plus’

There have been a number of variants of Delta and confusingly, many have earned the nickname “Delta plus”. That doesn’t mean they’re the same variant, just that they are similar derivations of Delta.

In July, a variant called AY.1 began circulating in India and was dubbed as “Delta plus”.

That variant has had next to no impact on cases in India which are now at their lowest for more than six months.

The current Delta plus, AY.4.2, was identified by British authorities in July. The UK has some of the world’s most comprehensive Covid-19 monitoring systems meaning new variants have a high chance of being found in Britain.

UK cases are rising compared to many other nations. Picture: Our World in Data

‘Urgent research’ needed into new mutation

On Monday, former US Food and Drug Administration Commissioner Scott Gottlieb sounded a warning bell over AY.4.2.

“We need urgent research to figure out if this Delta plus is more transmissible, has partial immune evasion,” Mr Gottlieb wrote on social media.

“There’s no clear indication that it’s considerably more transmissible, but we should work to more quickly characterise these and other new variants. We have the tools.”

UK reported its biggest one-day Covid case increase in 3 months just as the new delta variant AY.4 with the S:Y145H mutation in the spike reaches 8% of UK sequenced cases. We need urgent research to figure out if this delta plus is more transmissible, has partial immune evasion?

— Scott Gottlieb, MD (@ScottGottliebMD) October 17, 2021

The new Delta plus is, as the name suggests, a descendant of the Delta variant. It has a number of mutations that may – or indeed may not – be of concern.

Professor Francois Balloux of University College London’s Genetics Institute said AY.4.2 carried two spike mutations knows as Y145H and A222V. Spike proteins help the virus enter the cells.

“Both the Y145H and A222V mutations have been found in various other SARS-CoV-2 lineages since the beginning of the pandemic, but have remained at low frequency until now,” he said.

“It is potentially a marginally more infectious strain. Up to 10 per cent more transmissible.

“(But) it’s nothing compared with what we saw with Alpha and Delta, which were something like 50 to 60 per cent more transmissible. So we are talking about something quite subtle here and that is currently under investigation,” he told the BBC.

“At this stage I would say wait and see, don’t panic. It might be slightly, subtly more transmissible but it is not something absolutely disastrous like we saw previously.”

Delta plus AY. 4.2. variant contains mutations that may help bind the virus to spike proteins more easily. Picture: National Institutes of Health/AFP

Is Delta plus causing the UK surge?

The problem with working out if Delta plus is a threat is that there are many possible answers as to why British cases are rising.

“The situation in the UK is there is a lot of circulating virus there mainly in teenagers since they have recommenced school,” Prof Kelly said in Canberra on Wednesday.

“But very importantly, there has not been the same rises as we have seen before in the UK in terms of hospitalisations and death and that’s because the vaccination rollout in the UK has been very successful.”

Talking to news.com.au, Australian National University infectious diseases expert Professor Peter Collignon said it was likely there wasn’t a single reason – such as Delta plus – for why the UK cases were going up.

“The vaccination rates are lower than Australia; socio-economically we’re better off. So I think there’s lots of reasons.”

Rising cases are a challenge for Britain's Prime Minister Boris Johnson who was bullish in removing restrictions during the northern summer. Picture: Yui Mok/AFP

The UK for instance removed all restrictions when barely half the total population was vaccinated while many other countries waited until rates were higher. Mask wearing is less prevalent in the UK than some countries.

In addition, the UK’s head start on vaccination may mean immunity so no waning in some people. The emergence of any new transmissible strain was “suboptimal,” said Prof Balloux of Delta plus.

“But we are dealing with a potential small increase in transmissibility that would not have a comparable impact on the pandemic,” he said.

Nonetheless, virus watchers and health authorities will be observing AY.4.2 nervously to see if it is just another variant of no concern or whether it’s causing a spike in new cases just as the northern winter approaches.