Overview - AstraZeneca COVID-19 vaccine

Vaccines are the best way to prevent infectious diseases. They teach your immune system (your body's natural defences) how to protect you from a specific virus.

The official name of AstraZeneca's COVID-19 vaccine is 'Vaxzevria'. But most people call it 'AstraZeneca'.

The AstraZeneca COVID-19 vaccine protects any age group from COVID-19. But it's currently not recommended for people under the age of 50. This is because of a very rare risk of getting unusual blood clots with low platelets after having the vaccine.

This is a precaution because people under 50 are less likely to get severe COVID-19 disease and there are other vaccines available.

If you are under 50 and have already had the vaccine, there is no need to worry. You will be protected against COVID-19. The risk of illness if you get COVID-19 is much higher than any risks associated with the vaccine.

Read about the very rare side effects and new guidance


You will need 2 doses of the AstraZeneca COVID-19 vaccine.

You should get your 2nd dose at least 12 weeks after your 1st dose if you are:

  • aged 60 or older
  • at high or very high risk of severe COVID-19

If you are under 60 without a high-risk, or a very high-risk medical condition, you should wait until 16 weeks have passed to get your 2nd dose.

This has increased from 12 weeks. The extra time is to allow more research as more evidence becomes available.

Read about how long it takes to work


Vaccines teach your immune system how to protect you from diseases.

It takes 3 weeks, after getting the 1st dose, for the AstraZeneca COVID-19 vaccine to work.

You will have the best protection from COVID-19 after the 2nd dose.

Read more about immunity after the AstraZeneca COVID-19 vaccine

Vaccine bonus

28 days after your 1st dose of the AstraZeneca vaccine, you can follow the same 'vaccine bonus' public health advice as fully vaccinated people. This does not include foreign travel.

You still need to get your 2nd dose to make sure that your vaccine protection lasts.

Read about the 'vaccine bonus' public health advice on gov.ie


The AstraZeneca COVID-19 vaccine was developed in line with international standards of safety.

It has been tested with thousands of people as part of clinical trials.

Read more about the safety of the AstraZeneca COVID-19 vaccine

Side effects

Like all medicines, vaccines can cause side effects. Most of these are mild to moderate and short-term.

Not everyone gets side effects.

Read more about side effects after the AstraZeneca COVID-19 vaccine

Which vaccine is best

All vaccines are tested for safety and effectiveness before they can be used. The HSE only uses a vaccine if it meets the required standards of safety and effectiveness.

You should get any vaccine that is offered to you.

Read more about COVID-19 vaccine development

If you are pregnant or breastfeeding

If you have not been given a vaccine yet, you will be offered a different COVID-19 vaccine to the AstraZeneca vaccine.

If you have already had your 1st dose of the AstraZeneca vaccine, you should still get your 2nd dose.

The benefits of getting your vaccine far outweigh any risks. You will be at greater risk of severe illness if you do not get your 2nd dose.

Wait at least 12 weeks before you get the 2nd dose.

Being fully vaccinated will reduce the chance of you becoming very unwell.

Read more about COVID-19 vaccines in pregnancy

Read more about COVID-19 vaccines if you are breastfeeding

This content was fact checked by vaccine experts working in Ireland

Last updated: 10 May 2021 at 1.50pm