Boris Johnson has raised the prospect of mass testing for coronavirus and social distancing allowing the UK to return to some form of normality by the summer, while stressing that tougher measures such as shutting down cities remained a possibility.

The next 12 weeks could “turn the tide of this disease”, Johnson told the daily Downing Street press conference on the pandemic, saying it was possible to “send coronavirus packing in this country, but only if we all take the steps we have outlined”.

Flanked by his chief scientific adviser, Patrick Vallance, and chief medical adviser, Chris Whitty, Johnson did not announce any new measures to keep people separated and slow the spread of the virus, such as a much reported plan to severely restrict movement in London.

“We’re guided very much by the science and whether we think the advice we have given is working,” Johnson said, when asked whether new restrictions could be introduced. But, he added, if current measures were not working, “nothing is ruled out”.

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Striking a notably, if cautiously, optimistic note, Johnson said: “I think, looking at it all, that we can turn the tide within the next 12 weeks and I’m absolutely confident that we can send coronavirus packing in this country. But only if we all take the steps that we’ve outlined – that is vital.”

The PM based his assessment on experimental treatments for the virus, saying the first UK patients had that day been part of a randomised test for one drug, and also the possibly rapid rollout of an antibody test “as simple as a pregnancy test”, which could determine if someone has had the Covid-19 virus.

“That knowledge of where the virus is will make a huge difference to our management of the disease and our ability to reduce disruption and economic difficulty,” Johnson said, saying hundreds of thousands of the tests could be bought.

Johnson did stress the test had not yet been proven. Whitty also urged some caution, warning that while an antibody test looked possible, it remained to be seen whether the ones being offered now worked well enough.

The PM was at pains to dispel rumours of imminent and robust new measures in London, such as forcing bars and pubs to close, and limiting movement – but warned that people needed to abide by social distancing rules, saying adherence was “very patchy” in some parts of the capital.

“There is no prospect of us wanting to stop public transport in London or stop the tube or the buses,” he said. “We are going to want people to avoid gatherings where they transmit the disease. If it becomes necessary to do more to ensure that, we will certainly do so.”

On measures to help people who are losing jobs because of business disruption from the virus, Johnson promised details would come via the chancellor, Rishi Sunak, but provided only vague reassurances. “We will stick by businesses, I hope business will stick by their employees,” he said.

Quick guide What to do if you have coronavirus symptoms in the UK Show Hide Symptoms are defined by the NHS as either: a high temperature - you feel hot to touch on your chest or back

a new continuous cough - this means you've started coughing repeatedly NHS advice is that anyone with symptoms should stay at home for at least 7 days.

If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home. After 14 days, anyone you live with who does not have symptoms can return to their normal routine. But, if anyone in your home gets symptoms, they should stay at home for 7 days from the day their symptoms start. Even if it means they're at home for longer than 14 days. If you live with someone who is 70 or over, has a long-term condition, is pregnant or has a weakened immune system, try to find somewhere else for them to stay for 14 days. If you have to stay at home together, try to keep away from each other as much as possible. After 7 days, if you no longer have a high temperature you can return to your normal routine. If you still have a high temperature, stay at home until your temperature returns to normal. If you still have a cough after 7 days, but your temperature is normal, you do not need to continue staying at home. A cough can last for several weeks after the infection has gone.

Staying at home means you should: not go to work, school or public areas

not use public transport or taxis

not have visitors, such as friends and family, in your home

not go out to buy food or collect medicine – order them by phone or online, or ask someone else to drop them off at your home You can use your garden, if you have one. You can also leave the house to exercise – but stay at least 2 metres away from other people. If you have symptoms of coronavirus, use the NHS 111 coronavirus service to find out what to do. Source: NHS England on 23 March 2020

But in one politically striking answer, Johnson said the economic response to the pandemic would be “different from 2008”, saying that, after the banking crash, ordinary workers had not been assisted in the way the banks were. The mantra would be “looking after the people first”, Johnson said.

Asked about hospital capacity, especially in London, Whitty said intensive and respiratory care would be “first point of pressure”, and that even with proper social distancing, patient numbers would rise for the next two weeks.

Whitty said it was up to people to abide by guidance: “There’s a lot of evidence a huge proportion of people are – we don’t know if it will be enough.”

Other priorities, he said, would be to test more NHS staff for the virus, and to roll out more protective equipment for them.