Figures released by the Scottish Social Attitudes Survey, and compiled between October 2021 and March this year, show 66 per cent of Scots thought the standard of the NHS had fallen in the previous 12 months.
Despite this, 54 per cent of the respondents said they were satisfied with the way the NHS was run, compared with 28 per cent who said they were unsatisfied.
The figures don’t take into account the past seven months, which has seen accident-and-emergency (A&E) waiting times increase to record levels, a staffing crisis in health and social care settings, and the imminent threat of strike action by NHS staff over below-inflation pay offers.
Recent figures show just 64.2 per cent of people attending A&E are being seen within four hours, despite Scottish Government targets of 95 per cent.
Meanwhile, Mr Yousaf has said the NHS will take at least five years to return to normal, and warned the coming winter will be "the most challenging the NHS has faced".
Speaking to BBC Scotland, Mr Yousaf said: “It is not performing at the level that any of us would like, that is stating the obvious.
"There's myriad factors – the effect of the pandemic being the most significant, but it's not the only factor.
"One of the biggest problems in our hospitals is the high level of delayed discharge – 1,800 people who are clinically safe cannot get out because local authorities are unable to provide social care, either at home or care home places."
All NHS staff are being offered a flat £2,205 pay rise, which on average amounts to a 7 per cent increase, following negotiations between the Government and trade unions.
However, the Royal College of Nursing said the offer amounts to a real-terms pay cut, the Royal College of Midwives has described the offer as “deeply insulting”, and the Chartered Society of Physiotherapy said the offer was “a kick in the teeth” for its members.
Scottish Labour health spokesperson Jackie Baillie said: “The voice of Scotland’s frontline medics is clear. Our NHS is in crisis and this Government is missing in action.
“For 15 years this SNP Government has failed to tackle the staffing crisis at the heart of our NHS, all the while the working conditions and welfare of frontline workers has declined.
“We now face a humanitarian crisis in our NHS with lives being lost as a result.
“Humza Yousaf cannot keep deflecting responsibility for the SNP’s failure, whilst hopelessly promising change in five years' time as a crisis of deadly magnitude unfolds on his watch. We need urgent action now before winter sets in.”
The survey separately found 66 per cent of people in Scotland trust the Scottish Government, compared to 22 per cent who trust the UK Government to do the right thing.
Scottish constitution secretary Angus Robertson said: “The findings in this survey demonstrate continued faith in the Scottish Government to deliver on behalf of the people of Scotland.
“They clearly show that despite these uncertain times, people agree with the Scottish Government’s priorities.”