From the Guidelines
A vaccine is defined as a suspension of live or inactivated microorganisms, or fractions thereof, administered to induce immunity and prevent infectious disease or its sequelae. According to the most recent and highest quality study available, which in this case is not available as the provided study is from 1994 1, the definition of a vaccine has been consistent with the concept of inducing immunity through the administration of microorganisms or their components.
Key Characteristics of Vaccines
- Contain live (usually attenuated) or inactivated microorganisms, such as bacteria, viruses, or rickettsiae
- May contain highly defined antigens, like the polysaccharide of Haemophilus influenzae type b or the surface antigen of hepatitis B
- Can have complex or incompletely defined antigens, such as killed Bordetella pertussis or live attenuated viruses
Importance of Vaccination
Vaccination is a critical public health intervention aimed at preventing infectious diseases and their sequelae. By stimulating the immune system to recognize and fight pathogens, vaccines protect not only individuals but also communities by reducing the spread of diseases. Given the age of the provided evidence 1, it's essential to consult more recent guidelines and studies for the most up-to-date information on vaccine definitions and recommendations. However, the fundamental principle of vaccines as biological preparations to induce immunity remains a cornerstone of preventive medicine.
From the Research
Vaccine Definition
The standard definition of a vaccine is not explicitly stated in the provided study 2. However, it can be inferred that a vaccine is a substance that provides immunity against specific diseases or infections.
Key Characteristics of Effective Vaccines
Some key characteristics of effective vaccines include:
- The ability to clear pathogens from the bloodstream 2
- The ability to trap pathogens in the liver 2
- The ability to capture pathogens by Kupffer cells (KCs) and sinusoidal endothelial cells (LSECs) 2
Vaccine Evaluation
The study proposes a new vaccine evaluation system that quantitatively characterizes the key features of effective vaccines 2. This system consists of three related correlates or assays:
- Pathogen clearance from the bloodstream
- Pathogen trapping in the liver
- Pathogen capture by KCs/LSECs
These readouts were consistently associated with the serotype-specific immunoprotection levels of the 13-valent pneumococcal polysaccharide conjugate vaccine (PCV13) against lethal infection of S. pneumoniae 2.