Professor Kingston Mills thinks it's needed to protect against the Indian variant.
There are calls for people who have one dose of the AstraZeneca covid vaccine to be topped up with a different jab to protect against the Indian variant.
A new UN report says cases of the variant have been identified in at least 53 territories.
128 cases of the strain have been found in Ireland.
Trinity College professor, Mullingar's Kingston Mills says efficacy against it is as low as 60 percent with the AstraZeneca vaccine: