A NEW COVID variant is being closely monitored by the World Health Organisation (WHO) following a rise in infections in several parts of the world.

First identified at the end of January, the variant – officially named NB.1.8.1 and informally known as Nimbus – has become increasingly common here in Ireland, as well as across Europe, the Americas, south-east Asia and Australia. 

Just over one in ten Covid cases in Ireland in the last few weeks was the Nimbus variant – but the numbers overall still remain low. 

So what is known about the new Nimbus strain?

Is it more infectious?

Nimbus carries genetic mutations that may make it more infectious and better able to evade certain antibodies – essentially meaning it is more transmissible than previous strains.

However, the WHO has graded the overall public health risk from the strain as ‘low’ on a global scale.

Like other variants, Nimbus has changes to its spike protein — the part of the virus that helps it enter human cells.

These changes may increase its ability to spread and weaken the effect of antibodies from previous infections.

Even so, the WHO reports there is no evidence that Nimbus causes more severe illness than other currently circulating strains, and it has not led to higher hospitalisations or death rates.

What are the symptoms?

The symptoms linked to the Nimbus strain are much the same as those seen with other Covid variants.

They include sore throat, cough, tiredness, fever, muscle aches, loss of taste or smell, breathing difficulties, nausea, vomiting, and diarrhoea.

While this variant may partially bypass some immune defences, WHO experts say this level of “immune escape” is similar to that seen in previous Omicron subvariants.

Importantly, the variant does not appear to resist antiviral treatments, and current vaccines still offer strong protection against serious illness.

When did the new strain enter Ireland?

According to the WHO, the strain first appeared in January and by late April it was responsible for around 10.7% of global infections, up from just 2.5% a month earlier.

The strain has seen a rapid rise in Ireland in recent weeks.

According to data from the Health Protection Surveillance Centre (HPSC), the proportion of sequenced Covid samples linked to Nimbus jumped from 3.7% to 27.3% in the recent weeks.
NB.1.8.1 accounted for 11% of total positive Covid tests in the last 5 weeks in Ireland.

Don’t panic though, cases are not spiking. Last week, there were just 216 cases of Covid reported in Ireland, with 90 hospitalisations attributed to Covid.

Most of the recorded cases (around 55%) were people over the age of 65, the most vulnerable age group, which explains the high rate of hospitalisation.

While 216 cases may seem like a lot, cases were significantly higher this time last year – over 1,000 cases were reported every week in June 2024.

Cases have remained low this year. In recent weeks, the average amount of recorded cases was just over 160.

What can I do?

However, for those at higher risk – including older adults, people with weakened immune systems, or those with chronic health conditions – Nimbus does pose a potential threat.

The WHO advises that these groups keep up to date with booster jabs to maintain strong protection against severe Covid outcomes.

While there are no longer any self-isolation mandates in the Ireland, the HSE recommends avoiding contact with others for five days if you experience symptoms.

The HSE also advises you to avoid meeting people who are at very high risk for ten days.

Seasonal Covid booster shots will be available in autumn, and are recommended for people who are most at risk of severe illness.