People with conditions such as leukaemia, advanced HIV and recent organ transplants who are over the age of 12 will be given a third jab following a recommendation from the Joint Committee on Vaccination and Immunisation (JCVI).
The announcement is separate to any decision on a booster programme, but it is understood news on that is expected soon.
Scotland’s Chief Medical Officer Dr Gregor Smith said: “As we have done throughout the pandemic, we will continue to follow the expert advice from the JCVI and in line with their most recent guidance, people aged 12 years and over who are currently severely immunosuppressed will now be offered a third dose of a COVID-19 vaccine, subject to their clinician’s medical advice.
“The advice is that a third primary dose should be given at least 8 weeks after the second dose, though the exact timing will be decided by the clinicians involved in each patient’s care as they will need to consider their current clinical conditions due to their underlying disease and any treatments the individual is receiving.
“The JCVI has also advised that where possible mRNA vaccines should be used for the third dose. However they state that AstraZeneca can be given to individuals who have received this vaccine previously, if this would facilitate delivery.
“Work is underway to ensure this third dose is offered to these patients as soon as possible.
“The recent increases in case numbers mean it remains crucial everyone who is offered a vaccination takes up the invitation.”
Professor Wei Shen Lim, chair of Covid-19 Immunisation for the JCVI, commented: "We want people with severely suppressed immune systems to have the best chance of gaining protection from Covid-19 via vaccination.
Health Secretary Sajid Javid said the UK Government was continuing to plan for a booster programme to begin this month and said people most at-risk from Covid-19 would be prioritised for that.
Charities working with people who will be eligible for a third dose welcomed the announcement as it will offer "much-needed reassurance and additional protection".