Like all medicines, COVID-19 vaccines can cause side effects. Most of these are mild to moderate and short-term. Not everyone gets side effects.
If you are concerned about side effects, phone your GP for advice.
Serious side effects, like a severe allergic reaction, are extremely rare. Your vaccinator is trained to treat allergic reactions.
Fever after COVID-19 vaccines
It’s common to develop a fever (temperature of 38 degrees Celsius or above) after COVID-19 vaccination. This usually happens within 48 hours of getting a vaccine.
If you feel uncomfortable, take paracetamol or ibuprofen following the instructions on the box or leaflet.
Booster doses
Many countries have given multiple doses of COVID-19 vaccines. There have not been any unexpected side effects for people who have had multiple boosters.
Adapted mRNA vaccines
The side effects of the adapted mRNA vaccines are similar to the previous Pfizer/BioNTech vaccines.
The safety of the vaccines will continue to be monitored by the European Medicines Agency (EMA).
If you have had anaphylaxis (severe allergic reaction) to Trometamol, you should not get the adapted mRNA vaccines.
Side effects of COVID-19 vaccines
The side effects of the COVID-19 vaccines used in Ireland are listed below.
Pfizer/BioNTech COVID-19 vaccine side effects
The Pfizer/BioNTech COVID-19 vaccine is called Comirnaty.
Novavax COVID-19 vaccine side effects
The Novavax COVID-19 vaccine is called Nuvaxovid.
Vidprevtyn Beta COVID-19 vaccine side effects
The Vidprevtyn Beta COVID-19 vaccine is available as a booster dose to people age 18 and older.
Moderna COVID-19 vaccine side effects
The official name of this COVID-19 vaccine is 'Spikevax.' It is not currently available in Ireland.
Janssen COVID-19 vaccine side effects
The Janssen COVID-19 vaccine is called Jcovden. It is not currently available in Ireland.
AstraZeneca COVID-19 vaccine side effects
The AstraZeneca COVID-19 vaccine is called Vaxzevria. This vaccine is not currently available in Ireland.
Reporting side effects of COVID-19 vaccines
As with all vaccines, you can report suspected side effects to the Health Products Regulatory Authority (HPRA).
If you are reporting a side effect to the HPRA
Give as much information as possible. Include the vaccine batch number if you have it. You'll find this on your vaccine record card. You can also ask your doctor or a family member to report side effects for you.
The HPRA cannot provide clinical advice on individual cases. Talk to your doctor or pharmacist about any medical concerns you may have.
Safety of COVID-19 vaccines
All vaccines are tested to make sure they are safe and work before they can be used. The HSE only uses a vaccine if it meets the required standards of safety and effectiveness.
You will be offered the vaccine that is most suitable for you.
Mpox vaccine
If you recently had the Mpox vaccine, wait 4 weeks before you get vaccinated with any COVID-19 vaccine. This is a precaution because of the unknown risk of myocarditis.
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This content was fact checked by vaccine experts working in Ireland.