Summary
Highlights
Immunization is the process of becoming immune or protected against a disease, typically through a vaccine. Vaccines stimulate the immune system to defend the body against illness. The immune system identifies and destroys harmful germs based on antigens on their surfaces. After an infection, the immune system creates memory cells, providing natural immunity. However, relying on natural immunity from getting the disease can lead to severe complications or death, as seen with polio, measles, and whooping cough.
Vaccines protect against diseases and their harmful symptoms. They usually contain weakened or killed germs, or genetic material that instructs the body to produce the germ's antigen. When vaccinated, the immune system learns to recognize and fight these germs by creating memory cells and antibodies without causing illness, preparing the body to effectively combat future infections.
There are several types of vaccines. Live attenuated vaccines use weakened live germs for strong immunity (e.g., MMR, chickenpox). Inactivated vaccines use killed germs, often requiring booster shots (e.g., hepatitis A, polio). Toxoid vaccines target harmful toxins produced by germs and also need boosters (e.g., diphtheria, tetanus). Subunit and conjugate vaccines use specific parts of a germ and may also require boosters (e.g., pertussis, hepatitis B). mRNA vaccines instruct cells to make antigens to trigger an immune response (e.g., certain COVID-19 vaccines). Viral vector vaccines use a safe virus to deliver genetic material for antigen production (e.g., certain COVID-19 vaccines).
Vaccines not only protect individuals but also the community through herd immunity. When a large percentage of the population is vaccinated, the spread of disease is significantly reduced, protecting those who cannot be vaccinated due to weakened immune systems, allergies, or other health conditions. Vaccination is crucial for safeguarding individual, family, and community health against dangerous and potentially deadly diseases.