How is a new vaccine developed?

COVID-19 vaccines are our best hope to end the pandemic – but how are they developed, and how do we know they are safe?

With so much misinformation out there about vaccines, it’s important to understand the scientific process that researchers around the world follow as they develop new vaccines.

A new vaccine goes through four stages of testing, from pre-clinical tests through to human trials. At each stage, scientists measure its effectiveness and safety. If a vaccine causes harmful side effects, or does not trigger an immune response, the vaccine trial is cancelled.

There are many COVID-19 vaccines currently in use. Dozens more are being trialled. Our video explains the journey that each of the candidate vaccines will go through to ensure they are safe and effective.