People aged 18 to 34: deciding on COVID-19 vaccines

If you are aged 18 to 34 you have a choice between 2 types of vaccine:

  • mRNA vaccines like the Pfizer/BioNTech and Moderna COVID-19 vaccines - these are recommended for people under the age of 50
  • viral vector vaccines like the Janssen and AstraZeneca COVID-19 vaccines - there is a very rare risk of unusual blood clots with low platelets with these vaccines

If you opt in for a viral vector vaccine, you may be vaccinated sooner, depending on supply.

All COVID-19 vaccines are free, safe and will protect you from severe illness from COVID-19.

How to get your vaccine

Moderna or Pfizer

You can register online to get the Moderna or Pfizer vaccine at a vaccination centre.

AstraZeneca vaccine

You can also register online to get the AstraZeneca vaccine at a vaccination centre. You'll have a choice to opt in or out of getting the AstraZeneca vaccine.

Opting in means you will be offered the AstraZeneca vaccine if a Moderna or Pfizer/BioNTech vaccine is not available.

If you do not opt in, you will automatically get a Moderna or Pfizer/BioNTech vaccine.

Janssen vaccine

You can get the Janssen single-dose COVID-19 vaccine in a pharmacy if you’re aged 18 to 34. You don’t have to register online with the HSE for this. You just need to book an appointment with a participating pharmacy.

If you are waiting on a pharmacy appointment, you can also register online. You may get your vaccine quicker this way.

If you get an AstraZeneca or Janssen vaccine

If you decide to get the AstraZeneca or Janssen COVID-19 vaccine, you may be vaccinated earlier. This means you will be protected from COVID-19 sooner. This includes protection from the Delta variant.

There is a very rare risk of developing unusual blood clots with low platelets if you get either of these vaccines. The risk is higher in people under 50, but it is still very rare. 

If you get either of these vaccines, it's important to know the symptoms of unusual blood clots so that you know when to get medical help.

Read about the side effects of the:

If you get a Moderna or Pfizer vaccine

Moderna and Pfizer are the recommended vaccines for people under the age of 50. This is because of the very rare risk of unusual blood clots linked to people under 50 who got the AstraZeneca or Janssen vaccine.

It's still safe to get the AstraZeneca or Janssen vaccine. But blood clots with low platelets is not a known side effect of the Pfizer or Moderna vaccine.

All COVID-19 vaccines give you good protection from severe illness from COVID-19 when you are fully vaccinated. But based on the evidence we have, the Pfizer and Moderna vaccines give you slightly higher protection from COVID-19 than AstraZeneca or Janssen.

If you register to get the Pfizer or Moderna vaccine, you will usually get an appointment at a vaccination centre around 3 to 4 weeks after you register. 

COVID-19 is usually a mild illness in young people but this is not always the case. You could still become very unwell.

Read more about the side effects of:

If you are pregnant

If you are pregnant, the Pfizer or Moderna vaccine are the recommended COVID-19 vaccine options.

Read about COVID-19 vaccines and pregnancy


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

Last updated: 21 July 2021 at 9.30am