Ireland will likely administer 40,000 fewer vaccines this week than had been expected.
This is because of disruption caused by the AstraZeneca vaccine.
Use of the jab has been suspended for most age groups over blood clot fears.
HSE boss Paul Reid insists there will be a short term impact.
But he says the overall rollout aim, for 80 per cent of adults to get a first dose by the end of June, is still on track.
