Britain's Prime Minister Boris Johnson joins in the applause on the doorstep of 10 Downing Street in London during the weekly "Clap for our Carers" Thursday, May 7, 2020. The COVID-19 coronavirus pandemic has prompted a public display of appreciation for care workers. The applause takes place across Britain every Thursday at 8pm local time to show appreciation for healthcare workers, emergency services, armed services, delivery drivers, shop workers, teachers, waste collectors, manufacturers, postal workers, cleaners, vets, engineers and all those helping people with coronavirus and keeping the country functioning while most people stay at home in the lockdown. (AP Photo/Alberto Pezzali)

The U.K. government has replaced its "stay at home" coronavirus slogan with a new "stay alert" message, raising concerns about the potential danger of mixed messaging ahead of a speech Sunday in which Prime Minister Boris Johnson will lay out the stages for lifting the country's lockdown.

The government-ordered lockdown, which began March 23, has reduced the transmission of the virus, but the daily death toll remains uncomfortably high. The U.K. recorded nearly 32,000 deaths as of Sunday, the most in Europe and the second-highest pandemic toll worldwide.

Johnson, who returned to work only two weeks ago following his hospitalization for COVID-19, is expected to announce in a prerecorded televised address only modest changes to the lockdown terms in England The devolved governments in Scotland, Wales and Northern Ireland have already extended the lockdown for another three weeks.

Ahead of his speech, Johnson sought to flesh out the meaning of the new "stay alert" slogan as telling the public to "stay at home as much as possible," to keep two meters (over 6 feet) apart "where possible" when going out and to limit contacts with other people.

The leaders of Scotland, Wales and Northern Ireland said they would retain the "stay at home" message. Up until now, the four nations of the U.K. have moved in lockstep on virus regulations.

Britain's Prime Minister Boris Johnson prepares to light a candle at the Grave of the Unknown Warrior in Westminster Abbey in London, Thursday May 7, 2020, ahead of commemorations to mark the 75th anniversary of VE Day on Friday. (Leon Neal/Pool via AP)

Scottish First Minister Nicola Sturgeon said she didn't know what the new advice meant and that she has asked the U.K. government not to promote what she considers to be a "vague and imprecise" message in Scotland.

"There is always a risk of mixed messaging," the first minister said during a press briefing. "The default stay at home message remains."

Health experts also expressed concern that the new slogan lacks clarity and may lead to an increase in "risky behavior" by the public that could cause infections to accelerate again and produce a second peak in -related deaths.

Professor Til Wykes of the Institute of Psychiatry, Psychology and Neuroscience at King's College London said people need "clear, concise and accurate" messages on what to do during the pandemic.

"This one is concise only," she said. "It will just be confusing, be open to misinterpretation and likely to increase risky behavior."

Britain's Prime Minister Boris Johnson joins in the applause on the doorstep of 10 Downing Street in London during the weekly "Clap for our Carers" Thursday, May 7, 2020. The COVID-19 coronavirus pandemic has prompted a public display of appreciation for care workers. The applause takes place across Britain every Thursday at 8pm local time to show appreciation for healthcare workers, emergency services, armed services, delivery drivers, shop workers, teachers, waste collectors, manufacturers, postal workers, cleaners, vets, engineers and all those helping people with coronavirus and keeping the country functioning while most people stay at home in the lockdown. (AP Photo/Alberto Pezzali)

Communities Secretary Robert Jenrick said the prime minister will also detail a new virus alert system that uses a five-level scale and on which the U.K. currently stands at four.

"Our aspiration is to bring that down as swiftly as we can to three," he said. "And at each stage, at each of those milestones, we will be in a position to open up and restart more aspects of the economy and of our lives."

Other modest changes to the lockdown are expected, including allowing people to exercise more than once a day and garden centers to reopen. New advice on face coverings and increased fines for those breaching lockdown rules are also anticipated.

The worry is that a more dramatic easing of the will lead to a second spike in infections and deaths—something that health experts predict will occur as nations ease lockdowns.

  • A Guardsman walks through St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • People take a walk in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • A woman feeds a parakeet in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • People exercise in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • People exercise in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • People on the promenade during the warm weather in Brighton in East Sussex, England as the UK continues in lockdown to help curb the spread of the coronavirus, Saturday May 9, 2020. (Gareth Fuller/PA via AP)

  • People enjoy the sunny weather in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • Cyclers pause at parliament square in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. (AP Photo/Frank Augstein)

  • People on Brighton Beach in East Sussex, England as the UK continues in lockdown to help curb the spread of the coronavirus, Saturday May 9, 2020. (Gareth Fuller/PA via AP)

  • People exercise in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

  • People exercise in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

  • Kite surfers in action in the shallows as walkers stroll along Tynemouth beach as colder weather hits the North east coast of England, Sunday May 10, 2020. The highly contagious COVID-19 coronavirus has impacted on nations around the globe, many imposing self isolation and exercising social distancing when people move from their homes. (Owen Humphreys / PA via AP)

  • People exercise in St James Park in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

  • People cycle through Westminster area of London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

  • People cycle and jog along The Mall in London, Sunday, May 10, 2020, during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

  • People cycle and jog along The Mall in London, Sunday, May 10, 2020 during the nation-wide coronavirus lockdown. Personal exercise while observing social distancing measures is allowed under government lockdown guidelines. (AP Photo/Frank Augstein)

Johnson's Conservative government has also faced criticism for being too slow to react to the pandemic and for not supplying medical workers with enough protective gear.

Johnson is also expected to announce that everyone flying into the U.K. will have to quarantine for 14 days unless they are coming from Ireland. The U.K. government has authority on border issues over the devolved administrations.

Karen Dee, the chief executive of the Airport Operators Association, said she has not received any details about any proposed quarantine plan but warned that it would have a "devastating impact" on the U.K.'s aviation industry as well as the wider economy.