How Do Vaccines Work?
Vaccines are biological preparations that provide active acquired immunity to a particular infectious disease. They contain antigens, which are parts of the pathogen (virus or bacteria) that stimulate the immune system to recognize and combat the disease.
Mechanism of Action
When a vaccine is administered, it introduces a harmless component of the pathogen, such as a killed or weakened form of the germ, or a piece of its structure like a protein. This exposure prompts the immune system to respond as it would during an actual infection.
Creating Immunity
Following vaccination, the body produces antibodies and trains immune cells, such as T and B lymphocytes, to recognize and attack the pathogen in future encounters. This generates immunological memory, allowing the body to respond more swiftly and effectively if exposed to the disease later on.
Types of Vaccines
There are several types of vaccines:
- Inactivated or killed vaccines: Contain pathogens that have been killed or inactivated.
- Live attenuated vaccines: Use a weakened form of the germ.
- Subunit, recombinant, or conjugate vaccines: Include only parts of the pathogen.
- mRNA vaccines: Deliver genetic instructions to produce a harmless piece of the pathogen.
Public Health Impact
Vaccination programs have played a pivotal role in controlling and even eradicating diseases such as smallpox and polio, significantly improving global health outcomes and reducing healthcare costs.