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Weak immune system and COVID-19 vaccines

You should get a COVID-19 vaccine this autumn or winter if you have a weak immune system.

Having a weak immune system puts you at higher risk of serious illness if you get COVID-19.

Getting vaccinated will give you some protection against this. Talk to your GP or healthcare team about getting a COVID-19 vaccine.

You should get a COVID-19 vaccine twice a year.

If you've never had the COVID-19 vaccine and have a weak immune system

If you have a weak immune system and have not had the vaccine before, you should have:

  • 2 doses, 4 weeks apart - as your first round of COVID-19 vaccination

You may get:

  • a third dose 8 weeks after this - only if advised by a specialist

If you've never had the COVID-19 vaccine and you get a COVID-19 infection, you should wait at least 4 weeks after your infection before getting vaccinated.

How to get your COVID-19 vaccine

Pregnant and weak immune system

If you are pregnant and have a weak immune system you should get vaccinated.

Some women also need a second dose. Your GP or healthcare team will advise you.

COVID-19 vaccination in pregnancy

Safety and side effects of COVID-19 vaccines

COVID-19 vaccines used in Ireland are approved by the European Medicines Agency (EMA)

Safety and side effects of COVID-19 vaccines used in Ireland

Page last reviewed: 16 September 2025
Next review due: 16 September 2028