Patients at an Aberdeenshire GP practice are being offered re-vaccination amid fears drugs may have been stored at the wrong temperature.
There are 260 children and adults at Cruden Medical Group in Hatton being contacted by NHS Grampian.
The health protection team said the vaccines will not cause harm, but may not provide long-term protection.
The vaccines involved are those given for tetanus, diphtheria, polio, and hepatitis A and B.
The problems could stretch back as far as June last year.
The treatments concerned are those given as part of the childhood vaccination programme and some travel-related vaccines given to adults.
A check found that vaccines kept in the practice fridge might have been stored at temperatures outside the range recommended by the vaccine manufacturers.
Dr Diana Webster, consultant in public health medicine, told BBC Scotland: "This is a very unusual event.
"There is always a risk with fridges. There is going to be an investigation."
She added: "We have sought expert advice and been advised the majority of patients involved should be offered a booster vaccination as a precautionary measure.
"We can reassure parents and patients there is no significant risk associated with receiving an additional dose of vaccine."
A helpline has been set up for patients on 08000 282 836 which is available from 0800 BST and 2200 BST.