Vaccines teach your immune system how to protect you from diseases.
It is much safer for your immune system to learn how to protect you from COVID-19 through vaccination than by catching the virus.
We do not know yet how long immunity will last. Clinical trials are ongoing to find this out.
How long it takes to work
It takes 7 days after the second dose for the Pfizer/BioNTech COVID-19 vaccine to work.
You should get your second dose 3 to 4 weeks after your first dose.
Protection from COVID-19
After having both doses of a COVID-19 vaccine, most people will be protected against the virus.
There is a small chance you might still get COVID-19 after vaccination. Even if you do get COVID-19, being vaccinated can reduce how serious your symptoms will be.
There is some new evidence to show that the vaccines may reduce you spreading COVID-19 to other people but more research is needed.
The HSE, Department of Health and the World Health Organization recommends that you get your COVID-19 vaccine when it is offered to you.
Even after you are vaccinated, continue to follow public health advice on how to stop the spread of COVID-19. For example, social distancing, wearing a face covering and washing your hands properly and often.
If you take immunosuppressive medicines
If you have a weakened immune system, your COVID-19 vaccine may not work as well for you. But there is no extra risk in getting it.
COVID-19 vaccine testing and evidence
The Pfizer/BioNTech vaccine has been tested on people aged 16 and older.
In clinical trials, the vaccine reduced the risk of people getting COVID-19 by 95%. Results also show that the Pfizer/BioNTech vaccine works well in adults of any age.
New evidence from Israel shows the risk of severe COVID-19 was reduced by 92%, 7 days after 2 doses of the Pfizer/BioNTech vaccine.
This content was fact checked by vaccine experts working in Ireland
Last updated: 29 March 2021 at 12pm