Inactivated whole agent. These vaccines are not designed for people who have
an abnormal immune system. The inactivated whole agent vaccine uses dead
microbes that were killed by phenol or formalin. Common inactivated whole
agent vaccines include those for pneumonia, Salk polio, rabies, influenza, typhoid,
and pertussis (commonly known as whooping cough).
Toxoids. The toxoid vaccine is made of toxins produced by a virus or bacteria
that has been inactive. They are then used against toxins that are produced by a
disease-causing microorganism. Patients require a booster vaccination every 10
years because the toxoid vaccine does not provide lifelong immunity. Common
toxoid vaccines include those for diphtheria and tetanus.
Subunit. These vaccines have few side effects. The subunit vaccine uses frag-
ments of a microorganism to create an immune response. Subunit vaccines are
produced by using genetic engineering techniques to insert the genes of an anti-
gen into another organism are called recombinant vaccines.Common subunit
vaccines include those for hepatitis B.
Conjugated. These are fairly new in development and are designed for children
under 24 months whose immune system normally does not respond well to vac-
cines based on capsular polysaccharides. These polysaccharides are T-independent
antigens. The vaccine is produced by combing the polysaccharides with a protein.
Nucleic acid. These vaccines are in the animal testing stage. The nucleic acid
vaccine, which is also called the DNA vaccine, contains plasmids of naked DNA
and is designed to produce protein that stimulates an immune response. The
nucleic acid vaccine has a strong effect on large parasites and viruses.
Developing a Vaccine
Vaccines are developed by cultivating a large quantity of pathogen, which is
a disease causing organism. Some pathogens, such as the rabies virus, can be
cultivated in animals. For example, a chick embryo is commonly used to grow
viruses and is the method used to develop the influenza vaccine.
When vaccines were first introduced against measles and polio they would
only grow in humans. However, with the development of cell culture tech-
niques, cells from humans and primates enable large-scale viral growth. Scientists
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