People under 30 are due to receive their first Covid jabs over the next two weeks.
NHS Shetland says its vaccination centres will be running at both the Independent Living Centre and at Gilbertson Park.
Clinics continue to offer first and second doses of the Astra Zeneca vaccine.
But those in the 18-29 age group – the last group to be called – will receive the Pfizer vaccine, the recommended jab for the younger age group.
Pfizer clinics are also being run for pregnant women.
Teenagers aged 16 or 17 may also receive the Pfizer vaccination, but only if they are in a high risk group.
NHS Shetland’s interim director of public health Susan Laidlaw urged those aged 18-29 to expect a call offering an appointment.
“If you are in this age group, look out for a call from an unknown or withheld number over the next few days,” she said.
“If you miss a call we will keep trying before sending you a letter. When you get your appointment, please make sure you know which venue you have been asked to attend as both centres are being used for these clinics.”
Storage and transport requirements mean all jabs using Pfizer will be carried out in Lerwick.
“Pfizer is now the recommended vaccine for this age group, unless someone has a specific allergy to it,” Dr Laidlaw added.
“The Pfizer clinics are also for young people aged 16-17, but only if they are in a high risk group and have not yet had the vaccine; and for pregnant women.”
Dr Laidlaw has also called on those in their 40s who have not yet had been vaccinated or received an appointment to call the health board on (01595) 743319 and leave a message.
She also highlighted information about the Covid vaccination on the NHS Inform website.
Vaccination clinics operate on an appointment only basis. People are being urged not to simply turn up and ask to be vaccinated.