Vaccines are one of our most powerful tools against infectious diseases, including zoonoses. They work by stimulating the body's immune system to recognize and fight specific pathogens.
Key Components of Vaccines:
Antigens: Specific parts of pathogens that trigger an immune response
Nucleic Acids: Some modern vaccines use DNA or RNA that code for antigens
How Vaccines Work:
Introduce antigens or genetic material coding for antigens
Stimulate immune system to produce antibodies and memory cells
Provide immunity without causing the disease
Types of Vaccines:
Live attenuated (weakened pathogens)
Inactivated (killed pathogens)
Subunit (specific parts of pathogens)
Toxoid (inactivated toxins)
Conjugate (combining antigens)
mRNA (genetic instructions for antigen production)
Herd immunity
Herd immunity occurs when a large portion of a population becomes immune to a disease, making its spread from person to person unlikely.
Interdependence:
Members of a population are interconnected in building herd immunity. Each immune individual helps protect others who are not immune.
Threshold:
A certain percentage of the population must be immune to effectively impede transmission. This threshold varies depending on the disease's infectiousness.
Calculation:
The herd immunity threshold (HIT) can be estimated using the basic reproduction number (R₀) of a disease:
