A leading scientist says a case where almost everyone at a 60th birthday party developed the Omicron variant within days provided a "good argument" for cancelling Christmas gatherings.

Tim Spector, Professor of Genetic Epidemiology at King’s College London, who heads up the ZOE Covid study app, said contributors were already playing a vital role in helping scientists understand the new variant, which is said to be more transmissable than Delta.

To date, 110 cases of Omicron have been confirmed by genomic sequencing in Scotland but the true figure appears to exceed 1000 once other highly probable or possible cases are included.

From tomorrow restrictions will be tightened to require all household contacts of anyone who tests positive for Covid - even if they are not identified as an Omicron case - to self-isolate for 10 days regardless of vaccination status.

Prof Spector said that without any government mitigations whatsoever, the UK would be looking at 100,000 cases per day by Christmas. 

READ MORE: Sturgeon: 'Think carefully' about socialising amid warning of 'tsunami' of infections

Nicola Sturgeon warned earlier today that the country is on the cusp of a "tsunami" of infections and urged the public to reconsider plans for festive gatherings, following an earlier warning by Public Health Scotland.

Prof Spector said he was approached by a contributor who attended a 60th birthday party with 18 other guests last Saturday.

The Herald:

"Everyone took lateral flow tests, which is the sensible thing to do," he said.

“And on Sunday they were informed that one of the guests, who happened to be a teacher had tested positive.

“By last week, 16 out of 18 had fallen ill in some way. They were informed that it was Omicron, or probable Omicrom and they were waiting to get the genetic confirmations."

He said that while none became seriously unwell, all had been double or triple vaccinated and described the rapid spread of the virus as "worrying".

He said: "What was interesting was that the symptoms they reported were quite mild. Quite a few of them had nausea, slight temperature, sore throats, headaches but no one was bad enough to need a doctor or go to hospital.

“This suggests that in this group, who were all double or triple vaccinated, they do seem to work to reduce severe illness but it shows how easily one person can infect others in a close situation which is a worry.”

Professor Spektor said it was going to be “very difficult” to stop the spread of Omicron.

READ MORE: Two vaccine doses gives 'insufficient' protection against Covid 

“All we can really do to reduce the speed at which it infects people and try to protect the most vulnerable. I think this is a good argument for reducing gathering sizes and super-spreader events in the run up to Christmas.

“Sadly we had to cancel our Christmas parties at King’s and also at ZOE, which upset a lot of us.”

More than 4 million users are now contributing to the world’s largest ongoing study into the virus which has shaped health policy and tracked disease hotspots for more than a year.

In April, researchers discovered that loss of smell and taste (anosmia) was a key predictive symptom for the virus. This finding led the government to add anosmia to the official list of COVID-19 symptoms in May 2020.

Other key findings from the app include: early Covid-19 symptoms differ among age groups, delirium is a key sign of the virus in frail people and urban areas and areas of deprivation were most affected by Covid.

He urged the public to continue to report Omicron cases saying they would prove critical "before we get the full picture".