Up to 800 patients had to be revaccinated after recieving vaccines stored at the wrong temperature
A report claims hundreds of patients in Scotland were given vaccines that were stored at the wrong temperature following a "combination of systematic failures".
More than 800 people - half of them children - had to be revaccinated after NHS Grampian found the inoculations they received against serious diseases, including meningitis, hepatitis and polio, could be ineffective.
Health chiefs ordered an investigation after the blunder at Aberdeen's Northfield-Mastrick Medical Practice came to light.
The report, conducted by senior health board managers, discovered temperature recordings of fridges containing the vaccines were "incomplete".
They also found the temperatures were outside acceptable limits on a significant number of dates stretching back two years from September 2006.
The report states: "It is the considered view of the investigation team that the root causes of this incident are a combination of systematic failures."
The World Health Organisation states that vaccines must be stored between 2C and 8C to maintain their potency.
The report also makes a series of recommendations, including a review of vaccine policies and regular staff appraisals to ensure health workers are complying with the correct standards.
Dr Pauline Strachan, NHS Grampian's deputy medical director, said: "I would like to reassure the public that although this very unfortunate incident has happened, we have learnt the lessons from it and have put in place new practices and policies to ensure it does not happen again."