An immunologist has warned the new strain of Covid-19 could be causing different symptoms – including one that emerges during the night.

Omicron BA.5 is a highly-contagious subvariant prompting concern as it contributes to a fresh wave of infections across the globe, including the UK.

Scientists have been finding differences with previous strains, including the ability to reinfect people within weeks of having Covid.

A leading immunologist has now suggested it could be causing a new symptom among patients.

“One extra symptom from BA.5 I saw this morning is night sweats,” Professor Luke O’Neill from Trinity College Dublin told an Irish radio station in mid-July.

“Isn’t that strange?” he added.

BA.5 is driving a surge in cases in a number of countries along with BA.4, including across Europe and in Australia. It has also become the dominant variant in the US.

“The disease is slightly different because the virus has changed,” Professor O’Neill told Newstalk.

He added: “There is some immunity to it – obviously with the T-cells and so on – and that mix of your immune system and the virus being slightly different might give rise to a slightly different diease, strangely enough night sweats being a feature.

“But very importantly, if you are vaccinated and you’re boosted, it doesn’t progress into severe disease is the message to keep reminding people.”

BA.5 was first discovered in South Africa in February, one month after BA.4 was identified in the same country.

Both have since spread around the world and sparked concern over a resurgence in Covid infections.

It comes as coronavirus cases in the UK have risen by 7 per cent to 3.8 million in the week to 14 July, up from 3.3 million a week earlier, according to Office for National Statistics data.

The increase continues to be driven by the aforementioned sub-variants, the institution said.

The latest figures represent the highest estimate since late April, but is still below the record high of 4.9 million that was reached at the end of March.