Plan B: Boris Johnson reintroduces working from home guidance, expansion of face masks in public places and vaccine passports for large events

The Prime Minister, addressing the Downing Street press conference, has said the Government are introducing vaccine passports in large events, working from home guidance and expansion of settings in which masks are required.

Over 500 cases of the Omicron variant have been located in the UK.

However, he said 'the true number is certain to be much higher.'

Ministers had kept most of their Plan B measures in reserve for if Covid cases rise so high that they place the NHS under unsustainable pressure.

Ministers have been advised by Sage that vaccine certification may result in an increase of jab scepticism across the UK. As a result, requiring a negative Covid test may be the preferred option.

Working from home where possible has been re-introduced, with Sage advising the government "Sage has advised ministers that “working from home is one of the most effective measures available at reducing contacts”.

The Government has previously said it will seek to give businesses at least one week’s notice before mandatory vaccine certification is enforced.

Face masks have also been brought in for other settings, such as when moving around restaurants, while the Government has said the plan allows for “asking people once again to work from home if they can, for a limited period”.

The three main symptoms of Covid-19 include a new persistent cough, a high temperature and a loss of taste and smell.

Other experts have also warned that the symptoms will differ.

The Omicron variant has made its way across the UK and medics say it could be difficult to detect as the main symptoms are different from those laid out by the NHS.

Medics working in South Africa where the Omicron variant was first detected have however said that the main symptoms are fatigue, body aches and a headache.

The emergence of the new coronavirus variant known as Omicron has already impacted travel rules and sparked a return to compulsory mask-wearing on public transport.

Some 246 cases of Omicron – also known as B.1.1.529 – were confirmed in the UK as of Sunday.