A vaccine is a biological preparation that improves immunity to a specific disease by stimulating the body's immune system without causing the illness. It usually contains weakened or killed forms of the disease-causing microorganism, or parts of it, which allows the immune system to recognize, destroy, and remember the agent so it can respond quickly if exposed again in the future.
Vaccines work by triggering the immune system to produce a primary response, creating antibodies to fight the invader and special memory cells. These memory cells remember the pathogen, enabling a faster and stronger immune response if the real infection occurs later. This way, vaccines prepare the immune system to protect against serious disease without having to suffer from the actual infection.
Different types of vaccines use various forms of the pathogen, such as weakened live agents, inactivated (killed) agents, parts of the pathogen like proteins, or genetic material like mRNA, to safely stimulate immunity. Multiple doses may sometimes be required to build long-lasting immunity.
