The HSE says people in parts of Cavan were offered vaccination appointments in Meath to speed up the vaccine programme.
The issue came to light after some people in the Ballyjamesduff areas were given appointments in Navan, over 50km away.
The HSE has said there is no issue with the supply of vaccines to either centre in Cavan and Monaghan.
Concerns had been raised after people from parts of Cavan were given appointments at the Simmonstown centre in Navan, meaning they had to travel twice as far as they would to get to their nearest centre in Cavan town.
The HSE had previously said people would be given appointments in their nearest vaccination centre.
In a statement to Northern Sound News today, the HSE said "there may be slight variations between different vaccination centres in terms of the age year that they have reached and are scheduling appointments for".
It says "to address this, capacity has been scaled up and in cases people are being directed to an alternate location for vaccination".
People in the 50-59 age group in the Bailieborough and Ballyjamesduff areas who have an Eircode beginning with A82 will now be assigned appointments in Cavan town.
However, it says those already registered in the 60-69 bracket will have their appointment in Navan.
