ieExplains: What is the new covid variant and is it in Ireland?

In May, the World Health Organization (WHO) designated the NB.1.8.1 strain of covid as a 'variant under monitoring', and the public health risk posed by it is 'evaluated as low at the global level'. Picture: Alamy Stock Photo

Is there a new strain of covid?

Yes. It is called NB.1.8.1, and is a sub-variant of the Omicron variant.

Omicron was the dominant strain in Ireland at the end of 2021 and 2022. 

The new strain was first detected in January 2025.

What is the new strain?

In May, the World Health Organization (WHO) designated the NB.1.8.1 strain of covid as a “variant under monitoring", and the public health risk posed by it is "evaluated as low at the global level".

It said: "Currently, approved covid vaccines are expected to remain effective to this variant against symptomatic and severe disease. 

"Despite a concurrent increase in cases and hospitalisations in some countries where NB.1.8.1 is widespread, current data does not indicate that this variant leads to more severe illness than other variants in circulation."

The new strain comprised of 13.6% of all cases in the week ending May 18. While the percentage remains low, this is an increase from 0.7% in the week ending April 20. 

Have there been any cases in Ireland yet?

Yes. As of June 9, there are 19 cases linked to this variant of the virus detected in Ireland. The first case was detected here on April 16. 

In the five-week period from April 20 to May 24, the new strain accounted for 13.6% of all sequenced cases — compared to 4.3% in the previous five weeks. 

Those figures are based on GISAid sequence data. GISAid is a global science initiative that monitors and provides access to data on influenza viruses. 

In response to a query from the Irish Examiner, the HSE said that based on WHO data and on the mutation profile, there is no evidence of increased severity or impact on vaccine effectiveness against severe disease.

The HSE added that since the end of March 2025, levels of covid have shown a slow but steady increase. However, "levels of hospitalisations, ICU admissions, and deaths remain low".

Is it the only covid variant?

No. There are still multiple covid variants. In a statement last week, the WHO said that the variants "continue to evolve".

They said: "Between January and May 2025, there were shifts in global SARS-CoV-2 variant dynamics. At the beginning of the year, the most prevalent variant tracked by WHO at the global level was XEC, followed by KP.3.1.1.

"In February, circulation of XEC began to decline while that of LP.8.1 increased, with the latter becoming the most detected variant in mid-March. Since mid-April, the circulation of LP.8.1 has been slightly declining as NB.1.8.1 is increasingly being detected."

At the moment, six variants are being tracked.

What are the symptoms of the new covid variant?

Common symptoms align with typical Omicron subvariants from the height of the pandemic in 2021.

They include fatigue, fever, muscle aches, and a sore throat. 

Writing in The Conversation, Australian virologist Lara Herrero said: "The evidence so far suggests NB.1.8.1 may spread more easily and may partially sidestep immunity from prior infections or vaccination. These factors could explain its rise in sequencing data.

"But importantly, the WHO has not yet observed any evidence it causes more severe disease compared to other variants."

The WHO does note that the global public health risk associated with covid remains high. There has been evidence of "decreasing impact on human health" throughout 2023 and 2024.

The HSE has said that anyone with covid symptoms, even mild ones, should stay at home until 48 hours after their symptoms are mostly or fully gone.

People should also avoid contact with other people, especially people at higher risk of severe covid.