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AstraZeneca COVID-19 vaccine

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.

AstraZeneca COVID-19 vaccine

In clinical trials, the AstraZeneca vaccine reduced the risk of people:

  • getting COVID-19 by 60%
  • being hospitalised with severe COVID-19 by 100%

This vaccine has been tested on people aged 18 and older.

How COVID-19 viral vector vaccines work

The AstraZeneca COVID-19 vaccine is a viral vector vaccine.

Viral vector vaccines are like messengers. They use a weakened version of a different virus (the vector) to deliver instructions to cells in your body.

COVID-19 viral vector vaccines use the adenovirus as the vector. Adenovirus is the virus that causes the common cold.

The surface of the virus that causes COVID-19 is studded with proteins known as 'spike proteins'. The virus uses these spikes to enter human cells, infecting you with COVID-19.

When you get a viral vector vaccine, the vector (adenovirus) enters a cell in your body. It then teaches the cell how to produce the COVID-19 spike protein.

Protection after the vaccine

After you get your vaccine, your immune system recognises that the protein doesn't belong there. Your body then begins building an immune response to fight off what it thinks is an infection. This immune response makes antibodies.

The antibodies offer you protection from COVID-19. It is much safer for your immune system to learn how to protect you from COVID-19 through vaccination than by catching the virus.

How COVID-19 vaccines were developed quickly

The work to develop COVID-19 vaccines moved much faster than usual to make them available as soon as possible.

Read about COVID-19 vaccine development

Use of AstraZeneca COVID-19 vaccine restarted

Use of the AstraZeneca COVID-19 vaccine has been restarted after a short pause.

The AstraZeneca COVID-19 vaccine is safe and effective. Go to your appointment if this vaccine is offered to you.

Read more about the restart of AstraZeneca COVID-19 vaccinations

Ingredients of the AstraZeneca COVID-19 vaccine

The AstraZeneca COVID-19 vaccine does not contain eggs, preservatives or latex.

For a full list of ingredients, read the patient information leaflet for the COVID-19 AstraZeneca vaccine.

This content was fact checked by vaccine experts working in Ireland

More information

COVID-19 vaccine AstraZeneca – European Medicines Agency

Last updated: 9 April 2021 at 12.50pm