Alok Sharma was at No 10 day before displaying coronavirus symptoms

Alok Sharma, the business secretary, spent 45 minutes with Boris Johnson and Rishi Sunak in a meeting in No 10 the day before he fell ill with suspected coronavirus, raising the prospect they might have to self-isolate for two weeks.

Sharma has not had his test result back but he started feeling unwell at the House of Commons dispatch box on Wednesday afternoon and he has since gone into a 14-day isolation period.

The World Health Organization (WHO) guidance on face masks has remained consistent during the coronavirus pandemic. It has stuck to the line that masks are for healthcare workers – not the public. 

“Wearing a medical mask is one of the prevention measures that can limit the spread of certain respiratory viral diseases, including Covid-19. However, the use of a mask alone is insufficient to provide an adequate level of protection, and other measures should also be adopted,” the WHO has stated.

Nevertheless, as some countries have eased lockdown conditions, they have been making it mandatory to wear face coverings outside, as a way of trying to inhibit spread of the virus. This is in the belief that the face covering will prevent people who cough and sneeze ejecting the virus any great distance.

There is no robust scientific evidence – in the form of trials – that ordinary masks block the virus from infecting people who wear them. There is also concerns the public will not understand how to use a mask properly, and may get infected if they come into contact with the virus when they take it off and then touch their faces.

Also underlying the WHO’s concerns is the shortage of high-quality protective masks for frontline healthcare workers.

Nevertheless, masks do have a role when used by people who are already infected. It is accepted that they can block transmission to other people. Given that many people with Covid-19 do not show any symptoms for the first days after they are infected, masks clearly have a potential role to play, especially on crowded public transport as people return to work.

 Sarah Boseley Health editor

Downing Street said Sharma was in a face-to-face meeting with the prime minister and chancellor about the economy before cabinet on Tuesday morning. The cabinet room has been deep-cleaned.

Johnson’s official spokesman said the men were physically distanced, sitting at least 2 metres apart at all times, but did not wear face masks during the meeting.

He refused to say explicitly that Johnson would re-enter self-isolation if the business secretary had a positive result, and Johnson was asked to by the new test and trace service. He said only that the prime minister would “follow medical advice”.

Johnson has already had coronavirus but the guidelines for test and trace state that people have to self-isolate for 14 days if they have had contact with someone who has tested positive, regardless of whether they have been ill before or not.

The prime minister and chancellor may be able to avoid that outcome if the ministers are adamant that they were at least 2 metres apart at all times, but a refusal to do so could also undermine trust in the system.

The No 10 spokesman could not say whether Sharma’s test result would be returned on Thursday. The test and trace system only kicks in to find contacts of someone who is ill when a positive outcome is recorded.

Whether or not Sharma tests positive, his suspected illness is likely to cause concern about the government’s decision to bring back parliament in its physical form, after weeks of allowing MPs to attend remotely via video link.

Many MPs have protested against the new arrangements, which have resulted in them queuing around the parliamentary estate while complying with the physical distancing rules in order to vote.

During the debate, after Sharma was seen wiping his face with a handkerchief several times, his Labour shadow, Ed Miliband, passed him a glass of water. Sharma also appeared sweaty and sounded hoarse on Tuesday, according to one fellow MP, when he voted to abolish hybrid parliamentary measures.

During one vote, the minister voted straight after the culture secretary, Oliver Dowden, and immediately before the Labour MP Stephen Kinnock.

In another vote on the substantive motion, Sharma queued to vote immediately after Saqib Bhatti, the Conservative MP for Meriden, and just before Paul Scully, a Tory business minister.

Lisa Nandy, the shadow foreign secretary, said the development was “just awful”, adding: “The government stopped MPs from working from home and asked us to return to a building where social distancing is impossible. MPs are travelling home to every part of the country tonight. Reckless doesn’t even begin to describe it.”

Digital voting in the Commons was ended on Tuesday after MPs approved a government motion introduced by the leader of the house, Jacob Rees-Mogg, despite widespread objections.

The Labour MP Karl Turner said he had asked the Health and Safety Executive to conduct an urgent risk assessment of working conditions in parliament.

He said MPs having to “huddle together” on escalators on the parliamentary estate while lining up to vote were among a number of “unsafe practices”.

A string of cabinet ministers and senior officials have come down with coronavirus since the start of the pandemic, including Johnson, who was treated in intensive care.

Matt Hancock, the health secretary, Chris Whitty, the chief medical adviser, Mark Sedwill, the cabinet secretary, Dominic Cummings, the senior No 10 adviser, and Ben Wallace, the defence secretary, were also all unwell with coronavirus in late March or early April.

The first MP to fall ill with the virus was Nadine Dorries, a health minister, who tested positive in March.

A House of Commons spokesperson said: “The house’s priority is to ensure that those on the estate are safe while business is facilitated. We have closely followed guidance from PHE on action to take following a suspected case of Covid on site, including additional cleaning. Our risk assessment outlines the measures we have already put in place to reduce the risk of transmission in parliament.”