Antibodies, as their name implies, fight the virus, bacteria or parasite that enters your body. Your body produces specific antibodies against a particular germ. Once you have antibodies against virus X, for example, you are said to be immune from the disease caused by that virus. There are two ways in which this immunity comes about. First, the antibodies, which are produced, as a result of your vaccines will attack virus X if it should ever invade your body.
Vaccines protect most people from disease.
All of us react in different degrees to vaccines. Only a very small percentage of the population, which includes some smokers, people who are obese and others with underlying health problems, may not respond with sufficient antibodies to protect themselves fully against infections by bacteria or viruses. In general, vaccines are safe. But some may have side effects, such as soreness and swelling at the site of the injection. Some babies react with a fever, but anything more serious is rare and happens only if the person is hypersensitive to one or more of the components in the vaccine.