Simply Science 12
Vaccines work by stimulating the immune system to recognize and defend against specific pathogens, such as viruses or bacteria, without causing the disease itself. They do this by introducing a harmless part of the pathogen or a weakened or inactivated version of the pathogen into the body. When the immune system encounters these components, it learns to recognize and remember them.
Here’s a simple guide on how vaccines work.:
Exposure to the Antigen: A vaccine contains an antigen, which is a small piece of the pathogen that triggers an immune response. This antigen can be a weakened or inactivated form of the pathogen, a piece of the pathogen (e.g., a protein), or even genetic material (e.g., RNA or DNA) that codes for a part of the pathogen. Importantly, the antigen in the vaccine cannot cause the disease.
Immune Response: Once the vaccine is administered (typically through injection), the immune system recognizes the antigen as foreign and starts mounting an immune response. This response involves several key components:
Antigen-Presenting Cells (APCs): These cells, such as dendritic cells, engulf and break down the antigen. They then present fragments of the antigen (called antigens) on their surfaces.
Activation of Helper T-Cells: Antigen presentation activates helper T-cells, which play a central role in coordinating the immune response. They help activate other immune cells, including B-cells and cytotoxic T-cells.
Production of Antibodies: B-cells are activated and differentiate into plasma cells, which produce antibodies. Antibodies are proteins that specifically target and neutralize the pathogen or antigen. They can bind to the pathogen's surface and prevent it from infecting host cells.
Memory Cells: Some of the activated B and T-cells become long-lived memory cells. These cells "remember" the antigen and provide long-term immunity. If the same pathogen ever enters the body in the future, the immune system can quickly mount a strong response, often preventing illness.
Immune Memory: After the initial exposure to the antigen through vaccination, memory cells remain in the body for a long time, sometimes for years or even a lifetime. If the person is exposed to the actual pathogen in the future, the immune system can recognize it quickly and mount a rapid and effective response, preventing or reducing the severity of the disease.
Vaccines are designed to mimic natural infections without causing the disease itself. By training the immune system to recognize and remember specific pathogens, vaccines help protect us from infectious diseases.