A new variant of Covid-19 does appear to break through immune protection, but is not currently a cause for concern, the World Health Organization's Special Envoy on Covid-19 has said.

Dr David Nabarro said the virus is capable of forming new variants at "really quite a speed".

Speaking on RTÉ's Today with Philip Boucher-Hayes, he said:"BQ.1 seems to be able to move around more easily, but at the same time we don't think it’s causing more severe illness.

"We do think it can break through immune protection and has been reported from 65 countries from the end of October and the number seems to be increasing all the time. It doesn't add to my sense of anxiety about Covid, but this is a dangerous virus and we haven't seen the last of it yet."

He added the WHO has not placed it in the category of variant of concern "at this time".

"The factors that determine whether or not a variant is going to cause trouble relates to whether humans are susceptible to the variant and if the variant causes a nasty disease and it's the susceptibility criteria that always makes us nervous.

"Even if people have been immunised or have previous illness, a variant that's able to break through the immuno-protection is something to note and it's that part that everyone is going to look at," he said.

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Dr Nabarro said: "The reality is as long as these viruses are moving around there is a danger."

He said that as virus levels pick up, people need to be ready to put back on their face masks, maintain physical distance and perhaps to avoid going to crowded places if they are at risk.

"We're not just focusing on Covid but the unchartered territory of long Covid. About one in 20 people seem to get it, and they can be younger people, even children. That’s why we are encouraging people to be extra cautious".