Introduction to Vaccines and Vaccination

Introduction to Vaccines and Vaccination

VACCINE

  • A vaccine is a biological preparation that provides active acquired immunity to a particular disease.

  • A vaccine typically contains an agent that resembles a disease-causing microbe (MO) and is often made from weakened or killed forms of the microbe, its toxin, or one of its surface proteins.

  • The agent stimulates the body’s immune system (IS) to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future.

  • Types of Vaccines (PT):

    • Prophylactic Vaccine:

      • Designed to prevent or ameliorate the effects of a future infection by a natural or “wild” pathogen.

      • Examples include vaccines for influenza, measles, and polio.

    • Therapeutic Vaccine:

      • Currently being investigated for potential treatments against cancers and chronic diseases.

      • They aim to enhance the immune response against already established diseases.

VACCINATION

  • The administration of vaccines is called vaccination.

  • Vaccination is the most effective method of preventing infectious diseases.

  • Widespread immunity due to vaccination has largely contributed to the worldwide eradication of smallpox and the restriction of diseases such as polio, measles, and tetanus from much of the world.

  • The effectiveness of vaccination has been widely studied and verified.

    • Notable examples include the influenza vaccine, the HPV vaccine, and the chickenpox vaccine.

  • The World Health Organization (WHO) reports that licensed vaccines are currently available for 25 different preventable infections, showcasing the progress made in immunization practices.

  • The term "vaccine" and "vaccination" are derived from Variolae vaccinae (smallpox of the cow), a term that Edward Jenner devised to denote cowpox in his works.

    • In 1798, Jenner used this term in the long title of his "Inquiry into the Variolae vaccinae knows as the Cow Pox" to describe the protective effect of cowpox against smallpox, which laid the foundation for modern vaccination.

  • In 1881, to honor Jenner's contributions, Louis Pasteur proposed that these terms should be extended to cover the new protective inoculations being developed.

Historical Context (EL)

  • Edward Jenner (1749-1823):

    • Known as the Father of Vaccination/Immunization, Jenner noticed that milkmaids who developed cowpox were immune to smallpox.

    • He successfully protected susceptible individuals by vaccinating them with cowpox.

  • Louis Pasteur (1822-1895):

    • Known as the Father of Bacteriology, Pasteur significantly advanced the field of microbiology.

    • In the 1850s, he was able to filter microorganisms from the air and concluded this was the source of contamination.

    • Developing an aseptic technique using heat (called Pasteurization), he was able to work safely with microbes.

    • Pasteur prepared boiled broths in flasks with long narrow gooseneck tubes that were open to the air, allowing air to pass through while preventing microbial growth in the flasks.

    • His studies on the diseases of wine from 1850-1880 demonstrated that the alcoholic fermentation of grapes, fruits, and grains was caused by microbes, particularly yeasts in alcohol fermentation and Lactobacilli in lactic acid fermentation.

    • In 1877, he developed a vaccine for chicken cholera, further establishing the principles of vaccination and setting the stage for future vaccine development.