Supervalu and Axa loyalty card holders have been advised that a security breach affecting their credit card details only happened a month ago.
There had been fears that hackers may have gained access to the details of nearly half a million European card users two years ago in what's been described as a large and sophisticated criminal attack.
More than 70,000 Supervalu and Axa loyalty programme customers were advised earlier this month that their card details had been compromised.
They have now been told by the office of the Data Protection Commissioner that they need only check their statements for the past month.
Data Protection Commissioner Billy Hawkes says it should over a slight relief to those affected.
"It seems that the breach happened last month," he said.
"Which means that customers need only focus on transactions on their cards over the last month.
"Obviously, before that, it seems that hackers did not have access to this card information."