Hundreds of people are reported to be queuing at vaccine centres around the country on the first day over-40s are eligible for a booster.
The HSE has said there is a waiting time of three hours at Citywest, Dublin, where there are reports of significant tailbacks on the N7.
However, there are understood to be no delays, currently, at the Letterkenny Vaccination Centre.
People aged in their 40s are eligible to get Covid-19 booster vaccinations in Letterkenny from this morning.
Those in the 40-49 age group can attend the centre at the IDA Business Park, Ballyraine.
The walk-in clinic (no appointment needed) will be open from 9am to 7pm today.
It will also be open on Monday, 9am to 7pm, Tuesday, 1.30pm to 7pm, Thursday, 9am to 7pm and on Friday (Christmas Eve) from 8.15am to 12pm.
Members of the public will also be able to access the booster vaccines from their GPs and pharmacies.
Booster vaccinations for the 40-49 cohort had originally been slated to begin from 27 December, however that has now been brought forward.
The Chief Executive of the Health Service Executive, Paul Reid, has encouraged people to access a booster vaccine at the earliest opportunity.
