Vaccine is an injection that protects you against infectious diseases, which can make you very sick or even cause serious complications or death.
Most vaccines contain a small amount of bacteria, virus or toxin that has been weakened or killed in the lab. Chemicals may also be added that trick your immune system into thinking it’s coming into contact with the germ. These chemicals are called adjuvants.
Some vaccines contain antigens—things that provoke an immune response but don’t cause disease. These can be whole viruses or bacteria, weakened forms of toxins made by the bacteria or just parts of a virus or bacteria that look like the pathogen. Alternatively, some vaccines use the blueprint (DNA or RNA) for producing antigens instead of antigens themselves. These are called recombinant vaccines.
Scientists have been developing vaccines for more than a century. They can take decades to go from theory in the lab to testing in humans and then getting approved for use.
Vaccines help keep people healthy and able to do their jobs and care for their families, communities and the world. They reduce the number of people who get sick, which lowers health-care costs and allows children to attend school regularly and learn, adults to work and support their families and communities, and older people to stay active and live independently. Vaccines also help create herd immunity—when enough healthy people are vaccinated against a disease, it can’t spread from person to person and become an outbreak.
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