This article is part of a series of explainers on vaccine development and distribution. Learn more about vaccines – from how they work and how they’re made to ensuring safety and equitable access – in WHO’s Vaccines Explained series. Vaccines are supported by decades of medical research. They work by preparing the body's own immune system to recognise and defend against a specific disease. The volume of information available about vaccination can be overwhelming, so it’s important to talk through the topic. Available in different languages