a. Passive Immunity. Passive immunity differs from active immunity in that
antibodies from one person are given to another. In other words, antibodies produced
by active immunization in one person are transferred to a susceptible person. This type
of immunity provides immediate protection of short duration.
b. Natural Passive Immunity. Natural passive immunity is the process by
which antibodies are transferred to a baby from an immune mother by placental
transfer. This process forms complete, but temporary, immunity which may last from 6
to 12 months.
c. Artificial Passive Immunity. Artificial passive immunity is conferred by
injecting blood serum from an immune human into a susceptible person. This is used to
provide immediate protection in cases of known exposure or in the case of epidemics.
Complete protection is assured for 2 to 3 weeks.
a. Biologicals. The biologicals, or vaccines, are used as an artificial means to
augment the human resistance system to infectious organisms. Vaccines are dead or
living (but attenuated) suspensions of bacteria, rickettsiae, or viruses. In the
preparation of vaccines of living organisms, care must be taken to ensure that the
vaccine will cause antibody production, but not the disease itself. This is accomplished
by reducing the virulence of the microorganism through a multi-step dilution procedure.
b. Bacterial Vaccines. For the most part, bacterial vaccines are killed
suspensions of millions of the organism. For example, cholera vaccine is a suspension
containing eight billion killed Vibrio cholerae organisms per milliliter.
c. Protective Antibody Formation. The first attempt to induce protective
antibody formation in an individual was carried out by an English physician, Edward
Jenner, in 1796. Jenner inoculated an 8-year-old boy with pustular material from a
cowpox infection on the hand of a dairymaid. The boy experienced mild symptoms of
cowpox for about 8 days, then recovered completely. Later attempts to infect him with
the smallpox failed. This event is considered a major medical contribution; the last
naturally acquired case of smallpox in the world occurred in 1977. Global eradication
was certified two years later and confirmed in 1980 by the World Health Assembly.
a. Screen. Before a patient receives an immunization, certain precautions need
to be taken. The patient should be screened for possible allergies to the vaccine to be
used. Skin tests for sensitivity to horse serum antitoxins and antiserums should be
done prior to administration.