As with all new medicines, all vaccines are extensively tested for safety before they're made routinely available to the general public.
Safety monitoring continues even after a vaccine has been made available. That's because not all side effects are always noticed during the vaccine's development, especially if they're very rare side effects. All vaccines in general use are continually and carefully monitored to identify such side effects.
The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for checking the safety of medicines (including vaccines) that have been made available to the public.
The MHRA collects important information on vaccine safety via the Yellow Card Scheme, whereby anyone can report a suspected side effect to the MHRA. For more information on how to use it, go to our page on how to report a vaccine side effect.
As well as the Yellow Card Scheme, the MHRA uses a variety of other sources of safety information, including medical literature, safety studies done by vaccine makers, databases that track trends in illnesses, and other worldwide organisations.
Now, read about how vaccines work.
