The elderly patients were given saline solution after an astonishing blunder at a 40-bed facility in Lanarkshire.
Eleven people at the Millbrae Care Home in Coatbridge, which specialises in caring for those with dementia, were wrongly jabbed.
Last night, the health board issued an apology but admitted it cannot say how many other “vaccination errors” may have occurred.
The Scottish Government confirmed it was aware of the incident – which was not made public.
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It said it did not hold accurate nation-wide information on any similar mistakes.
The blunder has been revealed in documents, which also allege other failings at the home, seen by the Sunday Mail.
They detail how “frazzled looking NHS nurses” arrived at Millbrae on December 16 last year to administer correct vaccines after residents were earlier wrongly injected from vials of saline solution.
A small amount of saline is supposed to be mixed with the pure Pfizer/BioNTech vaccine after it is taken out of freezers and thawed and then injected into patients.
Opposition politicians believe the Millbrae incident raises serious questions for ministers.
Scottish Labour’s health spokeswoman Jackie Baillie said: “This alarming incident raises serious questions about the management of the vaccine programme and care sector.
“It is astonishing that the SNP doesn’t know how common these kinds of incidents are. Their complacency is jaw-dropping.”
Scottish Lib Dem leader and health spokesperson Alex Cole-Hamilton added: “I cannot imagine the stress and disappointment that people may have felt when they discovered they have not been immunised.
“Mistakes like these cannot be allowed to happen, especially during a pandemic, with more dangerous variants now at large.”
Scottish Conservative shadow social care minister Craig Hoy said: “It is concerning that this information has only come to light now.
“The SNP Government should be upfront wherever possible about the number of patients affected by this error.”
Staff at Millbrae, who have lodged documents in collective grievance case, have detailed other alleged failings at the home.
It includes how workers had to buy food for residents from a local garage because the kitchen had closed down, as well as having to cut up tights to make pants for holding incontinence pads in place and “begging” for cleaning wipes.
Employees also raised concerns over pay, staffing and conditions and said they had no confidence in management, who made them carry out tasks without proper training.
A source at the home said: “The work is relentless because there aren’t enough staff and so you don’t get the time to properly care for the residents.
“Things are the same for NHS staff dealing with the vaccines, they were all clearly frazzled and that is when hard-working people make mistakes.”
Unions claim that the jab blunder reveals a care industry in crisis as a result of under investment across the NHS and private sector.
GMB general secretary Gary Smith said: “Care has been the ‘crisis within a crisis’ during the Covid-19 pandemic and the treatment by Millbrae senior management of their staff and service users is another shameful case in point.
“It demonstrates why we need to tackle the understaffing crises in both social care and the NHS and why we need a national care service that properly values staff for the essential service they deliver.
“That means a £15-an-hour minimum wage, stronger rights at work, and regulation that works for staff and not against them. Everyone deserves so much better – staff, service users, and their families – but there will be more Millbraes unless government and employers are finally prepared to radically change and invest in social care.”
Millbrae operator Thistle Healthcare confirmed it was aware of the jab blunder at the home.
It refuted the grievance allegations and insisted there has been no food shortage, no shortage of hygiene products or issues on employee pay.
A spokesman said: “This is the first time this matter has been brought to our attention and we do not recognise the events as described in this document.
“The care sector as a whole faces immense challenges from staff shortages and the impact of Covid patients being transferred to care homes from hospital at the start of the pandemic. We are working alongside the Care Inspectorate to mitigate the impact of this as a process of continuous improvement.”
An official inspection report carried out in July by Scottish watchdog the Care Commission rated Millbrae’s performance as “weak” in supporting residents’ wellbeing and “weak” in providing support during the pandemic. The report said: “Staff seemed to be in a hurry and were very task focused. They did not have adequate time to spend with residents to provide person-centred support.”
It also said medication management was an area of concern, with “numerous examples of poor recordings”.
The Crown Office is investigating the deaths of 12 residents at Millbrae in line with a commitment to investigate more than 3000 deaths at care homes linked to Covid-19 across the country.
Trudi Marshall, Health and Social Care North Lanarkshire nurse director, confirmed the vaccination blunder which involved NHS staff. She said: “None of the residents who received the vaccine diluent came to any harm and they were re-vaccinated on the same day.
“This happened at the beginning of the care home vaccination programme and measures were put in place immediately to avoid any similar incidents.”
The Scottish Government has vowed to introduce a National Care Service to tackle concerns over the way the industry is run.
A spokesman said: “We were notified of the incident at the time and reassured by the health board that no harm was caused and that all residents affected received the appropriate vaccine the same day.”