vaccine

A vaccine is a substance (usually a liquid) given to you by a doctor or nurse, usually as an injection in your buttocks or arm. It prevents you from getting sick or a disease such as chickenpox, measles, mumps, influenza or covid-19. Vaccinations make you produce antibodies (commonly known as defences) against a disease virus that make it harder for you to get infected.

The more people vaccinated, the sooner herd immunity is achieved, which means that a sufficiently large number of people are protected against the virus that cause the disease, and therefore it is more difficult to get infected.