What is Pi? Covid’s next potential variant that could replace Omicron

It has been nearly three years since Covid-19 was first detected, and changed the world.

The virus that shut down the world would go on to mutate into new variants after it emerged in Wuhan, China in December 2019.

Omicron was the last major variant, identified in November last year but scientists are already looking at what could replace it – Pi.

The Omicron variant initially caused huge concern around the world, not least because it was found to be highly transmissible and the 32 mutations to its spike protein suggested it might resist current vaccines.

But 12 months later, Covid cases are now beginning to fall after a mild autumn wave driven by a cluster of Omicron subvariants, which virologists described as “Omicron’s grandchildren.” These include the BQ.1 and BA.2.75.2 subvariants, as well as XBB.

What is Pi?

Experts are now looking into whether a major new variant could arise through the winter and bring a new wave of infections.

If or when a new variant emerges, it would be called Pi, the next letter after Omicron in the Greek alphabet.

But is it really on the way, or have we finally seen the back of Covid-19 as a world-changing disease? Scientists aren’t yet sure.

At the recent Africa Health Research Institute, leading scientists from the UK, Japan and Australia gathered to discuss the outlook for Covid among other viral diseases such as HIV.

Professor Wendy Barclay, a virologist at Imperial College and member of the government’s advisory committee, Sage, told the Telegraph: “Are we going to see variants arise or future versions of this virus arise which come with more severe outcomes than currently the omicrons do, either because they escape some level of control that the vaccines give, or that they change inherently?

“I still don’t think that’s resolved. I still think we are in a phase where there’s an awful lot that we don’t know.”

How serious could it be?

Professor Greg Towers, of University College London, said he was hopeful that while there might be more changes in the genetic make-up of the virus, they would not result in a return to serious disease.

Professor Alexi Sigal of AHRI said there was debate between those who believed the currently more benign situation was because vaccines and infections had built an effective immunity wall, and others who thought the virus had evolved significantly to be less harmful but that such a shift could happen again in the other direction.

However, he warned that viral evolution could bring us back to square in the fight against Covid.

University of Warwick virologist Professor James Young said that the UK’s reduced testing regime could leave officials ill-equipped to confront oncoming issues of new variants such as Pi.

“We don’t have the testing and surveillance regimes we were running previously. People who are having PCR tests are being sequenced which is giving us the information but I worry it might not be representative enough for what’s going on,” he said.

What is the UK’s current Covid situation?

Estimates published in the first week of November by the Office for National Statistics suggested that infections in England started to fall at the end of October.

Some 1.6 million people in private households tested positive for Covid-19 in the week to October 24, down from 1.7 million the previous week.

Infections in England peaked at 3.1 million during the summer BA.4/BA.5 wave.

But experts are still urging caution was we head into winter.

Dr Mary Ramsay, director of public health programmes at the UK Health Security Agency (UKHSA), said: “It is hugely encouraging that Covid-19 cases and hospitalisations are still in decline.

“This goes to show how effective the vaccine programme continues to be and we thank everyone who has come forward for their latest vaccination so far.

“However, it is still vital that anyone who has not had their booster this autumn does so as soon as possible. Vaccination is still the best way to protect yourself, your family and the NHS, particularly as we head into winter.”