Partygoers have been urged to “keep calm and carry on” with their Christmas festivities, despite scientists raising the alarm about the risks associated with gathering for social events.

The Conservative Party chairman, Oliver Dowden, said his party had no intention of cancelling its own Christmas drinks, and that others should continue with their celebrations.

It comes after Prime Minister Boris Johnson, who received his booster dose of the Covid vaccine on Thursday, urged the public to “continue as they are” within the new measures introduced to stop the spread of the virus, following the emergence of the Omicron variant.

Senior Tories, including Health Secretary Sajid Javid, have looked to encourage the public to hold firm to their pre-Christmas plans, with the hospitality industry warning it had suffered a “slew of cancellations” after Omicron sparked fresh safety fears.

Mr Dowden told Sky News: “The message to people, I think, is fairly straightforward – which is: keep calm, carry on with your Christmas plans.

“We’ve put the necessary restrictions in place, but beyond that keep calm and carry on.”

The former culture secretary said he understood there were “concerns” about the Omicron variant of coronavirus, but argued the Government had put in place “sufficient” measures, such as reinstating rules around wearing face coverings in shops and on public transport, in response.

“People should continue with their plans as intended,” Mr Dowden said, as he encouraged people to take up the offer of a booster jab.

Asked about the Tories’ own party plans, he told BBC Breakfast: “I think it is still planned, and I don’t intend to cancel it as chairman of the Conservative Party.”

Medical experts have struck a more cautious tone, however, urging people to avoid large groups this winter.

Influential scientist Professor Peter Openshaw said he would not feel comfortable attending a party as the “chances of getting infected were too high”.

Prof Openshaw, a member of the Government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), told BBC’s Question Time: “Personally, I wouldn’t feel safe going to a party at the moment, if it involves being indoors in an enclosed space where you’re close to other people, and people are not wearing masks.

“Even if they’ve been tested and vaccinated, I wouldn’t feel safe.”

The British Medical Association (BMA) said people should be encouraged to “avoid large groups” and meet outdoors where possible over the festive period.

The debate over social gatherings comes as scientists continue to study the possible threat posed by Omicron.

A study in South Africa, where the mutation was first detected, has suggested that the variant has “substantial” ability to cause reinfection in people who have previously had Covid.

The research, which has not been peer-reviewed, found people who had tested positive for coronavirus could pick up the virus again, potentially causing a wave of infections in those with some prior immunity.

It did not say how the variant will behave when spreading in a highly vaccinated population such as the UK, or whether the virus can evade the protection offered by vaccines against severe disease.

But experts in the UK believe their research on the impact of booster vaccines could offer hope in the fight against Omicron.

The CovBoost study found that booster jabs may well offer good protection in the face of the variant.

A team studying the effects of third doses said the body’s T cell immune response after a booster shot is such that it may provide protection from hospital admission and death.

The study also backs up the UK’s decision to offer Pfizer or Moderna as a third shot, with mRNA jabs leading to the most significant rise in immunity levels.

Professor Saul Faust, trial lead and director of the NIHR Clinical Research Facility at University Hospital Southampton NHS Foundation Trust, said the vaccines worked well against existing variants, although Omicron was not tested in the study.

Asked specifically about Omicron, he said: “Our hope as scientists is that protection against hospitalisation and death will remain intact.”