People in Tayside and Fife have been booked for second Covid-19 vaccines too early.
A scheduling error affecting health boards across Scotland has meant patients have been given appointments sooner than eight weeks after their first dose.
The NHS encourages at least 56 days between first and second vaccine appointments.
A statement provided by both NHS Tayside and Fife said: “We have identified a very small number of people who have been invited ahead of the eight week interval recommended for their second dose appointment due to an error in the scheduling system affecting health boards across Scotland.
“Please check the number of days between your appointment.
“If you are 55 days and under (not eight weeks yet) please do not come to your appointment.”
No need to cancel
The statement said patients should not attend early appointments but they do not need to be cancelled.
Anyone affected will be sent a new appointment or can attend walk-in clinics after eight weeks after receiving the first dose.
However, if patients are immunosuppressed and have an earlier second dose appointment for clinical reasons, they are asked to attend as scheduled.
For the vaccine to work effectively against Covid-19, the gap between doses is essential.
The first dose helps to prime the immune system as it starts to develop a response to the virus. Time is needed to allow this process to develop properly.
The second vaccine will reinforce this new protection. Health experts say a second dose is essential for enhanced, long term protection.
Getting a second dose too soon could harm the effectiveness of the vaccine.