Vaccination
Article by: Saul Kit, Division of Biochemical Virology, Baylor College of Medicine, Houston, Texas.
Key Concepts
• Vaccinations serve to immunize people and other animals
against infectious bacteria, viruses, and parasites.
• In countries where vaccination programs seek to immunize
virtually all children under 2 years of age, most vaccine-
preventable diseases have been reduced by 95 percent or
more from prevaccine highs.
• Vaccines trigger an immune response against a particle
or a cell contained within the vaccine. This response leads
to an immunological memory and long-term protection
against the target pathogen.
• Attenuated-live vaccines, introduced by Pasteur in the
1880s, use live viruses that are made avirulent and thus
incapable of producing a disease. Today, such vaccines are
produced by removing the genes that promote virulence.
• Noninfectious vaccines—including inactivated killed
vaccines, subunit vaccines, DNA vaccines, and several
others—confer immunogenicity even after their infectivity
is inactivated by chemicals or radiation.
• Adjuvants—chemicals that enhance the potency of anti-
gens—are sometimes used as vehicles for vaccine delivery.
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Active immunization against a variety of microorganisms
or their components, with the ultimate goal of protecting
the host against subsequent challenge by the naturally oc-
curring infectious agent. The terms vaccination and vaccine
were originally used only in connection with Edward Jenner's
method for preventing smallpox, introduced in 1796. In 1881,
Louis Pasteur proposed that these terms should be used to de-
scribe any prophylactic immunization. Vaccination now refers
to active immunization against a variety of bacteria, viruses,
and parasites (for example, malaria and trypanosomes) [Fig. 1].
History
Over the course of more than 200 years, vaccination has
controlled nine major diseases: smallpox, diphtheria, tetanus,
yellow fever, whooping cough (pertussis), poliomyelitis (polio),
measles, mumps, and rubella. In addition, vaccinations against
influenza (flu), hepatitis B, pneumococci, and Haemophilus
influenzae type b have made major headway against these
infections. In the United States and other economically devel-
oped countries, where programs have been expanded to im-
munize virtually all children under 2 years of age, most vaccine-
preventable diseases have been reduced by 95% or more from
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Content
• History
• Attenuated-live vaccines
• Noninfectious vaccines
• Killed vaccines
• Polysaccharide vaccines
• Subunit vaccines
• Synthetic peptide vaccines
• Biosynthetic polypeptide vaccines
• Anti-idiotype antibody vaccines
• DNA vaccines
• Adjuvants
• Cytokines and immunomodulation
• Recombinant viral vectors and chimeric viruses
• Diarrheal disease vaccines
• Rotavirus vaccines
• Oral transgenic plant vaccines
• Cancer vaccines
