People over 40 are being encouraged to bring forward the date of their second Covid-19 vaccination appointment.
Many people in that age group have already been given appointments 12 weeks apart.
But recent advice from the Joint Committee on Vaccination and Immunisation says the interval should be eight weeks, where supply allows, particularly in areas where the Delta variant is a major threat.
Anyone in that age group, who has been given appointments 12 weeks apart, is now being encouraged to use an online tool to check the status of their second appointment.
Earlier slots can then be booked if the jabs are 12 weeks apart.
A national helpline - 0800 030 8013 - can also be used, and drop-in clinics are being set up across the country.
Health Secretary Humza Yousaf said: "We are working closely with NHS boards to ensure the number of appointments can be increased in line with national guidance to help combat new variants and provide protection to as many people as possible.
"Boards are boosting their capacity to administer second doses alongside the delivery of first doses to younger cohorts and appointments are now being issued in accordance with the new recommendation of an eight-week gap.
"The second dose is vital in providing greater and longer lasting protection against the virus – particularly the new Delta variant.
"In line with the advice from the JCVI, we encourage those whose appointment was already scheduled – which is mainly over 40s at this time – to use the NHS Inform online tool, drop-in clinics or the national helpline to get their second dose appointment as close to eight weeks after their first as possible.
"In the six months since vaccinations started in Scotland we have delivered first doses to more than three quarters of the adult population and second doses to more than half.
"We remain on track to offer the vaccine to all adults by the end of July, but the emergence of the new variant shows we cannot be complacent.
"The vaccination programme is one of the main ways – along with restrictions and testing – that we are working to beat this virus and so it is crucial that everyone attends for their appointments."