The World Health Organization (WHO) is closely monitoring a new COVID-19 variant BA.2.86, which has been nicknamed by scientists on social media as Pirola.

Here's what we know about the new strain so far.

Where has it been detected?

It's only been detected in four countries:

- Denmark
- Israel
- United Kingdom
- USA

What has it been classified as?

BA.2.86 is considered a Variant Under Monitoring.

The WHO said it made this classification because "due to the large number of mutations it carries".

It has three classifications for COVID-19 variants:

- Variant Under Monitoring (VUM)
- Variant of Interest (VOI)
- Variant of Concern (VOC)

By declaring a VUM , the WHO calls for a global review of the strain's epidemiology and the tracking of its characteristics and spread.

By comparison, the VOC declaration calls for a more extensive response.

The WHO is currently tracking seven VUMs and their descent lineages:

- BA.2.75
- BA.2.86
- CH.1.1
- XBB
- XBB.1.9.1
- XBB.1.9.2
- XBB.2.3

and three VOIs:

- XBB.1.5
- XBB.1.16
- EG.5.

How bad is it?

We don't know yet.

"More data are needed to understand this COVID-19 variant and the extent of its spread," the WHO said.

"But the number of mutations warrants attention.

"WHO will update countries and the public as we learn more."



Francois Balloux, professor of computational systems biology at University College London, agreed that the attention was warranted.

"BA.2.86 is the most striking SARS-CoV-2 strain the world has witnessed since the emergence of Omicron," Dr Balloux said.

"Over the coming weeks we will see how well BA.2.86 will be faring relative to other Omicron subvariants."

But he said it wasn't expected to behave differently from other Omicron strains.

"Even in the worst case scenario where BA.2.86 caused a major new wave of cases, we are not expecting to witness comparable levels of severe disease and death than we did earlier in the pandemic when the Alpha, Delta or Omicron variants spread, Dr Balloux said.

"Most people on Earth have now been vaccinated and/or infected by the virus.

"Even if people get reinfected by BA.2.86, immune memory will still allow their immune system to kick in and control the infection far more effectively."

However, he still said a major wave would be an "unwelcome event".

Why has BA.2.86 been nicknamed 'Pirola'?

That came from scientists on social media.

As of March this year, WHO decided to only Greek alphabet names to Variants of Concern.

So, as far as WHO's concerned, there's no official, non-numerical name for variants under monitoring or or interest.

But some scientists have suggested naming variants to make them easier for the wider public to understand.

The World Health Network, an organisation that defines itself as a "people’s task force promoting safety and support for everyone", says COVID variants should have nicknames.

It suggests drawing those names from astronomy — so think constellations, stars, moons, asteroids and exoplanets.

The name appears to have been suggested by a person who goes by @JPWeiland on the social media platform X — previously known as Twitter.

The user, who describes themselves as a scientist and infectious disease modeller, named it "after an asteroid that hangs out by Jupiter".

The name was picked "for its uniqueness".