Second dose - AstraZeneca COVID-19 vaccine

You should get your second dose of AstraZeneca 4 to 12 weeks after your first dose.

If you had a first dose of the AstraZeneca vaccine and you do not want a second dose of this vaccine, you can choose to get an mRNA COVID-19 vaccine instead. This will mean that you have completed your first round of COVID-19 vaccination.

mRNA vaccines available in Ireland are the Pfizer/BioNTech and Moderna COVID-19 vaccines. The Moderna COVID-19 vaccine is only used in adults aged 30 and older in Ireland.

How to get an mRNA vaccine for your second dose

If you want to get an mRNA vaccine after having 1 dose of the AstraZeneca vaccine, you can go to a dose 2 walk-in clinic.

Walk-in vaccination clinics are in different locations. You can go to any dose 2 walk-in clinic, it does not have to be near your home.

You should get either the Pfizer or Moderna vaccine at least 28 days after getting your first dose of AstraZeneca.

Bring your vaccination card that shows you have had 1 dose of the AstraZeneca vaccine.

Getting 2 different vaccines

You can choose to get an mRNA vaccine as your second dose after having one dose of the AstraZeneca vaccine. This has been approved by the National Immunisation Advisory Committee (NIAC) in Ireland.

So far, there have been no concerns about serious side effects with this option.

Some studies have found that side effects are more common than when 2 doses of the same vaccine are used.

These include:

  • pain where the injection was given
  • headache
  • muscle aches
  • tiredness
  • chills and fever

Read about the side effects of the Pfizer/BioNTech and Moderna COVID-19 vaccines.


This content was fact checked by vaccine experts working in Ireland.

Last updated: 23 December 2021 at 9.50am