NHS Dumfries and Galloway has issued safety advice to everyone in the region following the cyber attack that took place in February this year.
The BBC said the health board is expected to send out leaflets from the chief executive describing the situation as “extremely serious".
A ransomware group targeted the health board in February. When its demands were not met it published stolen files online.
The health board is planning to contact patients classed as high risk individually and is asking everyone to remain on their guard for any attempts to access their computer systems.
It confirmed in May that the cyber-criminals had published some children’s mental health data.
The leaflets will tell residents that the best approach is to assume that some data relating to them is likely to have been copied and published.
Published information includes X-rays, test results and letters between healthcare professionals.