Hi Cathy,
Thanks for getting back.
In terms of St Patricks Day: Guinness Storehouse remains open and Trinity is open from 12.00 - 16.30. The hop-on-hop-off bus tour service may be subject to public holidays or local events that involve road closures, like St. Patrick's Day and Christmas Day. You can look out for updates on their
service page.
Covid:From 1 February 2022: Vaccine certificates for the primary vaccination series will not be accepted for travel if more than 270 days have passed since the final dose in the primary vaccine series vaccine certificates based on booster/additional doses are not time-limited
Essentially you need "an accepted proof of vaccine"
which now requires a booster if your first vaccination series began more than 270 days ago. If your vaccine is 9 months old, and you now have a booster, you're good to go.
Please let me know if you have any more questions.
Many thanks,
Cathaoir