Vaccines are the safest way to prevent infectious diseases. They teach your immune system (your body's natural defences) how to protect you from a specific virus.
Protection from a COVID-19 vaccine, COVID-19 infection, or both, weakens over time. Protection can be increased by getting a booster dose. Some people at higher risk should get seasonal booster doses to extend the protection of COVID-19 vaccines.
Adapted vaccines
The European Medicines Agency (EMA) and National Immunisation Advisory Committee (NIAC) have recommended adapted mRNA COVID-19 vaccines as booster doses.
While all previous vaccines offer protection against COVID-19, the adapted vaccines are expected to give wider protection against COVID-19 variants. This includes Omicron variants.
Doses and immunity
The doses needed for COVID-19 vaccines used in Ireland are listed below.
If you have a weak immune system, you should have been offered an ‘additional dose’ to give you better protection. This is because your immune system may not respond as well to vaccination. You will still need booster doses after this additional dose.
Getting different vaccines
You may be offered a different vaccine for your second dose or booster dose to the one you originally had. For example, you may get a booster dose of the Pfizer/BioNTech after getting the AstraZeneca vaccine for your first 2 doses.
So far, there have been no concerns about serious side effects with this option. Some side effects may be more common if you get a different vaccine from the one you got previously. For example, pain, fever, headache and fatigue. These are short-lived side effects and will not last long.
Studies have found that the immune response after getting different vaccines may be as good as getting the same vaccine. In some cases, it can be better.
Vaccine types
The different types of COVID-19 vaccines that have been used in Ireland are:
- mRNA - Pfizer/BioNTech and Moderna
- viral vector - AstraZeneca and Janssen
- protein subunit - Novavax and Vidprevtyn Beta
Read about the different vaccine types - mRNA, protein subunit and how they work
Side effects and safety
Like all medicines, COVID-19 vaccines can cause side effects. Most of these are mild to moderate and do not last long.
Protection from COVID-19
Anyone who gets COVID-19 can become seriously ill or have complications. Getting vaccinated is the best way to protect yourself and others.
You can still get COVID-19 after vaccination. But being vaccinated can reduce how serious your symptoms will be.
Continue to follow public health advice on how to stop the spread of COVID-19. For example, washing your hands properly and often.
This content was fact checked by vaccine experts working in Ireland.