Pfizer is to offer its COVID-19 vaccine to family members of its own staff in Ireland, separate to the national rollout.
The independent programme will start next month and will start with over-60s, before moving on to other age-groups.
The drug company says the vaccines are separate to the supply it's providing to the Government.
Pfizer employs around 4,000 people here.
Sinn Féin's health spokesman, David Cullinane, says the programme must be fair.
He said: "While they do say it will be rolled out in line with the age cohorts, they also in my view need to demonstrate there will be no unfair advantage... and that simply because you are related to somebody, it doesn't mean you should get any of the vaccines quicker or speedier than anybody else.
"If Pfizer were making additional vaccines available, [it would be better] that they would be available to everyone on an equal basis."
Pfizer's mRNA-based jab has so far been the most widely used vaccine in Ireland, with over one million doses delivered to date.
The EU last week announced that the pharmaceutical firm is to deliver millions of extra doses to the bloc this quarter - including over 500,000 to Ireland.