A new strain of covid, known as NB.1.8.1, has emerged as a sub-variant of the Omicron variant. This variant was first detected in January 2025, following Omicron's dominance in Ireland at the end of 2021 and 2022.

The World Health Organization (WHO) designated the NB.1.8.1 strain as a "variant under monitoring" in May. The public health risk associated with this variant is considered low globally, with approved vaccines expected to remain effective against it for symptomatic and severe cases.

While there has been a slight increase in cases and hospitalizations in countries where NB.1.8.1 is prevalent, current data does not suggest that this variant leads to more severe illness than other circulating variants. As of the week ending May 18, NB.1.8.1 accounted for 13.6% of all cases, up from 0.7% in the previous month.

As of June 9, Ireland has reported 19 cases linked to the NB.1.8.1 variant, with the first case detected on April 16. Over a five-week period, this variant made up 13.6% of all sequenced cases, compared to 4.3% in the previous five weeks.

Despite the presence of this new variant, the Health Service Executive (HSE) has stated that there is no evidence of increased severity or impact on vaccine effectiveness against severe disease. While covid levels have been slowly increasing since March 2025, hospitalizations, ICU admissions, and deaths remain low.

It is important to note that NB.1.8.1 is not the only covid variant in circulation. The WHO has identified six variants currently being tracked, with shifts in global variant dynamics observed between January and May 2025.

Common symptoms associated with the new covid variant include fatigue, fever, muscle aches, and a sore throat. While there are concerns about its potential to spread more easily and partially evade immunity from prior infections or vaccinations, there is no evidence yet to suggest that it causes more severe disease than other variants.

The WHO emphasizes that the global public health risk from covid remains high, despite some improvements in human health impact in recent years. Anyone experiencing covid symptoms, even mild ones, should isolate at home until symptoms have mostly resolved and avoid contact with high-risk individuals.