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.
Pfizer/BioNTech COVID-19 vaccine
The first COVID-19 vaccine to be approved for use in Ireland by the EMA was the Pfizer/BioNTech COVID-19 vaccine. Its official name is "Comirnaty".
Millions of people in the UK and the US have been given the Pfizer/BioNTech COVID-19 vaccine.
Trials have shown that the Pfizer/BionTech vaccine is 95% efficacious. This means that 95% of people who got this vaccine in the trial were protected from COVID-19. This vaccine has been tested on people aged 16 and older.
It is an mRNA vaccine. mRNA vaccines teach your body how to make a protein that will trigger an immune response, without using the live virus that causes COVID-19.
How COVID-19 mRNA vaccines work
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.
mRNA COVID-19 vaccines contain the instructions for making this spike protein.
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.
Your cells then break down the instructions for making the spike protein and get rid of them from your body.
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.
Ingredients of Pfizer/BioNTech COVID-19 vaccine
The Pfizer/BioNTech COVID-19 vaccine does not contain eggs, preservatives or latex.
For a full list of ingredients, read the patient information leaflet for the Pfizer/BioNTech COVID-19 vaccine (Comirnaty).
This content was fact checked by vaccine experts working in Ireland
Last updated: 29 March 2021 at 12pm