Covid-related absences among NHS staff are at their highest since March, while a record 20,217 new positive cases were recorded on Monday.
The number of people in hospital with Covid has almost doubled in a week, to 1,031.
Parliament will be recalled on Wednesday for an urgent update on the current situation, it has been confirmed, with Nicola Sturgeon expected to announce whether the self-isolation period in Scotland will be reduced from ten to seven days in line with other devolved nations.
Current staff absences and hospitalisations are of “real concern”, nursing union RCN Scotland said, as they do not yet reflect the full impact of the festive period and are expected to rise further in the coming days.
“Nursing teams are already short staffed, with record levels of vacancies. They are mentally and physically exhausted after almost two years of relentless pressure,” said Eileen Mckenna, RCN Scotland Professional Practice Associate Director.
“We are seeing an increase in Covid-related absences and hospital admissions both of which are a real concern particularly as we’re yet to see the full impact of mixing over the festive period.
"Now is the time to ensure that staff are given the highest levels of PPE, to stop further transmission and infection in hospitals and ensure staff are properly protected at work.”
Ms Mckenna added: “If hospital admissions continue to rise then difficult decisions will have to be made by Scottish Government and health boards to prevent the existing workforce being spread too thinly which will impact on the quality of patient care.”
A record 20,217 new cases of Covid-19 were recorded in Scotland on Monday, almost double the 10,562 reported last Monday and up from the previous record of 16,857 reported on Thursday.
Some 1,031 people are now in hospital with Covid, almost double the previous week’s figure of 555, while 38 are in intensive care.
The daily data for January 1 and January 2 was also published on Monday.
A total of 17,065 new cases were reported on January 1, and 14,080 were reported for January 2.
Health Secretary Humza Yousaf wrote on Twitter in response to the figures: “Another record day positive cases and over 1,000 people in hospital with recently confirmed Covid-19.
"Advice remains to minimise contacts, if you are going to mix with others please do a lateral flow test.”
Covid-related NHS staff absences in the week to December 28 were at their highest since March, with an average of 3,316 each day.
This includes 1,765 nursing and midwifery staff, 65 medical and dental staff, and 1,466 other staff.
Reasons for absence include illness with Covid-19 and self-isolation, and the figures cover staff in hospitals and community health services but exclude GPs.
In the week to December 21, the most recent figures available, some 922 care home staff members were recorded as absent. This represents a rate of 2.5 per cent and the highest number since September, up from 520 the previous week.
Unlike for NHS staff, care home staff absences also include stress related to Covid-19.
RCN Scotland does not support calls from some for the self-isolation period in Scotland to be reduced, favouring a “cautious” approach in a bid to keep case numbers as low as possible.
Health and care staff are eligible for exemptions from the requirement to self-isolate, providing they are fully vaccinated, do not have symptoms and continue to test negative.
However, staff are affected by illness, the need to care for others who are self-isolating, and self-isolation while waiting for PCR test results.
The self-isolation period for contacts of those with Covid-19 has recently been cut to seven rather than ten days in Wales and Northern Ireland, following a previous reduction in England.
There have been suggestions the time period may be cut even further in England, with Chris Hopson, chief executive of NHS England organisation NHS Providers, saying this would be a “risk judgement” for the UK Government given the high rates of healthcare staff absences.
Parts of NHS England are in a “state of crisis” as a result of these absences and high levels of demand, the chief executive of the NHS Confederation warned on Monday.
Health boards across Scotland are also dealing with widespread staff shortages and intense demand, with reports of areas in NHS Lanarkshire and NHS Dumfries and Galloway being particularly under pressure.
Boris Johnson warned on Monday that “considerable” pressure on the NHS is likely to continue for weeks to come.
"There’s no question Omicron continues to surge through the country,” he said, adding: “I think we’ve got to recognise that the pressure on our NHS, on our hospitals, is going to be considerable in the course of the next couple of weeks, and maybe more.”
It would be “absolute folly to say that this thing is all over now bar the shouting,” he said.
Nicola Sturgeon will update MSPs on the current state of the pandemic during a special meeting of the Scottish Parliament on Wednesday.
Announcing the new proceedings, Holyrood’s Presiding Officer Alison Johnstone tweeted to say: “Parliament will sit at 2pm on Wednesday 5 January.
“The meeting – for an update and questions on Covid – will be entirely virtual.”
The First Minister will answer questions from opposition party leaders and backbenchers following her statement.