More than 600 patients may have to be re-vaccinated after a GP practice stored medications incorrectly over a period of nearly two years.
A Care Quality Commission (CQC) inspection discovered vaccines were stored at incorrect temperatures at Dr S Laybourn and Partners as far back as June 2014.
The practice has now written to 126 adults and the parents and guardians of 480 children to invite them to return for repeat vaccinations.
It said receiving a vaccination which has been stored at the wrong temperature was not harmful, and that it was safe for a child or adult to receive a second dose.
The CQC found that temperatures of the fridges used to store vaccines were found on several occasions to be outside the normal range of 2C to 8C in the first half of this year.
An investigation by the practice showed this error had occurred on various occasions since June 2014.
Following the inspection, the CQC rated the practice as good but said safety required improvement.
In its report published in September the CQC acknowledged that the practice had "systems in place for safe medicines management, however, not all staff acted in line with the cold chain procedures".
It said: "At the time of our inspection the irregularities had not been reported or recorded as a significant event.
"Consequently, action had not been taken and learning had not occurred, which could have prevented further vaccine fridge temperature anomalies."
The surgery said it has destroyed old vaccines and bought new supplies, purchased new fridge temperature monitors, and carried out training for staff on storage procedure.
The practice had shown evidence of taking action to improve safety after a patient was given an incorrect vaccine due to an abbreviated word being used in their record, the CQC said.
A spokeswoman for NHS England North (Yorkshire and Humber) said: "NHS England is committed to ensuring patients have access to safe, high quality primary care services.
"We have worked with the practice to identify the causes of this issue and to support them to put plans in place to minimise the risk of this happening again."