The COVID-19 vaccine recommended for most people in Ireland is the Comirnaty vaccine.
The Comirnaty vaccine is an mRNA vaccine and manufactured by Pfizer.
Comirnaty vaccine side effects
Like all medicines, COVID-19 vaccines can cause side effects.
Most side effects are mild to moderate and do not last long. Not everyone gets side effects.
If you are concerned about side effects, contact a GP for advice.
Very common side effects
Very common side effects may affect more than 1 in 10 people.
Very common side effects include:
- tenderness or swelling in your arm where you had the vaccine
- feeling tired
- headache
- muscle pain
- joint pain
- diarrhoea
- fever (temperature of 38 degrees Celsius or above)
- chills
In children age 6 months to 4 years, feeling irritable or drowsy are very common side effects.
Common side effects
Common side effects may affect up to 1 in 10 people.
Common side effects include:
- nausea
- vomiting
- redness in your arm where you had the vaccine
Find your patient information leaflet
There are more possible side effects of the Comirnaty vaccine.
You can find a full list of side effects in information provided by the manufacturer, such as:
- the patient information leaflet (PIL)
- the summary of product characteristics (SPC)
How to find your patient information leaflet online
You can find the SPC on the European Medicines Agency (EMA) website.
The European Medicines Agency (EMA) - ema.europa.eu
Very rare side effects
Serious side effects are extremely rare. Your vaccinator is trained to treat allergic reactions.
Myocarditis and pericarditis
Myocarditis and pericarditis are very rare side effects of the Comirnaty vaccine.
Very rare side effects may affect up to 1 in 10,000 people.
Myocarditis and pericarditis are inflammatory heart conditions.
Myocarditis and pericarditis may be more likely to happen:
- in young men
- after the second dose of the first course of the vaccine
- within 14 days of getting the vaccine
Urgent advice: Get urgent medical help if
you get any of the following symptoms in the hours or days after a COVID-19 vaccine:
- breathlessness
- palpitations (a forceful heartbeat that may be irregular)
- chest pain
Who should not get this vaccine
Most people can safely get the Comirnaty COVID-19 vaccine.
The vaccinator will ask you questions to check if it is safe for you to get the vaccine.
The Comirnaty COVID-19 vaccine is not recommended for people who had a severe allergic reaction to:
- an ingredient in the vaccine, such as polyethylene glycol (PEG)
- a previous dose of an mRNA COVID-19 vaccine
- trometamol – an ingredient in contrast dye used in MRI scans
- any ingredient in the vaccine - the patient information leaflet has a list of ingredients
You should not get the Comirnaty vaccine if a doctor told you not have an mRNA COVID-19 vaccine for medical reasons.
mRNA COVID-19 vaccines include the Comirnaty (Pfizer) or Spikevax (Moderna) vaccines.
When to talk to your doctor
Talk to your GP or specialist doctor before you get a COVID-19 vaccine if you:
- had a severe allergic reaction (anaphylaxis) in the past to any other vaccine or medicine
- had myocarditis and pericarditis after a previous dose of a COVID-19 vaccine
- have a condition called mastocytosis
- feel very unwell
Multisystem inflammatory syndrome (MIS-C)
Children who had MIS-C in the past can get the COVID-19 vaccine if both of these apply:
- the child has recovered from MIS-C
- at least 90 days have passed since the diagnosis of MIS-C
Mpox vaccine
Wait 4 weeks between the mpox vaccine and any COVID-19 vaccine. This is a precaution because of a possible risk of myocarditis.
Other COVID-19 vaccines
The Comirnaty COVID-19 vaccine is an mRNA vaccine. Some people cannot get an mRNA vaccine or choose not to get one.
In this case, the Nuvaxovid (Novavax) vaccine is usually recommended.
Nuvaxovid (Novavax) vaccine
The Nuvaxovid (Novavax) vaccine is not available in Ireland.
We are trying to get supplies of the vaccine but we do not know if or when it will become available.
You can phone HSE Live and ask to be contacted if the Nuvaxovid (Novavax) vaccine becomes available.
Freephone 1800 700 700
What to do if you have a side effect
Talk to your GP if you have any side effects after a COVID-19 vaccine.
Fever after COVID-19 vaccines
You can take paracetamol or ibuprofen if you have:
- a fever (temperature of 38 degrees Celsius or higher)
- aches and pains
Follow the instructions on the box or leaflet.
If your fever lasts more than 48 hours or if you are still concerned, talk to your GP.
If you are pregnant and you have a fever or aches and pains, you can take paracetamol.
Reporting side effects
You can report side effects to the Health Products Regulatory Authority (HPRA).
Your GP, nurse, pharmacist or a family member can also report the side effect to the HPRA.
COVID-19 vaccine adverse reaction report - hpra.ie
When you report a side effect
Give as much information as possible.
Include the vaccine batch number if you have it. The batch number is on your vaccine record card.
The HPRA cannot provide clinical advice on individual cases. Talk to your doctor or pharmacist about any medical concerns you may have.
This content was fact checked by vaccine experts working in Ireland.