WORLD OF MICROBIOLOGY AND IMMUNOLOGY Vaccine569•
Contemporary researchers are continually attempting to
develop new vaccinations against such diseases as Acquired
Immune Deficiency Syndrome (AIDS), cancer, influenza, and
other diseases.
Physicians have long observed that individuals who
were exposed to an infectious disease and survived were
somehow protected against that disease in the future. Prior to
the invention of vaccines, however, infectious diseases swept
through towns, villages, and cities with a horrifying
vengeance.
The first effective vaccine was developed against small-
pox, an international peril that killed thousands of its victims
and left thousands of others permanently disfigured. The dis-
ease was so common in ancient China that newborns were not
named until they survived the disease. The development of the
vaccine in the late 1700s followed centuries of innovative
efforts to fight smallpox.
The ancient Chinese were the first to develop an effec-
tive measure against smallpox. A snuff made from powdered
smallpox scabs was blown into the nostrils of uninfected indi-
viduals. Some individuals died from the therapy; however, in
most cases, the mild infection produced offered protection
from later, more serious infection.
By the late 1600s, some European peasants employed a
similar method of immunizing themselves against smallpox.
In a practice referred to as “buying the smallpox,” peasants in
Poland, Scotland, and Denmark reportedly injected the small-
pox virus into the skin to obtain immunity. At the time, con-
ventional medical doctors in Europe relied solely on isolation
and quarantine of people with the disease.
Changes in these practices took place, in part, through
the vigorous effort of Lady Mary Wortley Montague, the wife
of the British ambassador to Turkey in the early 1700s.
Montague said the Turks injected a preparation of small pox
scabs into the veins of susceptible individuals. Those injected
generally developed a mild case of smallpox from which they
recovered rapidly, Montague wrote.
Upon her return to Great Britain, Montague helped con-
vince King George I to allow trials of the technique on inmates
in Newgate Prison. Success of the trials cleared the way for
variolation, or the direct injection of smallpox, to become
accepted medical practice in England until a vaccinationwas
developed later in the century. Variolation also was credited
with protecting United States soldiers from smallpox during
the Revolutionary War.
Regardless, doubts remained about the practice.
Individuals were known to die after receiving the smallpox
injections.
The next leap in the battle against smallpox occurred
when Edward Jenner(1749–1823) acted on a hunch. Jenner
observed that people who were in contact with cows often
developed cowpox, which caused pox but was not life threat-
ening. Those people did not develop smallpox. In 1796, Jenner
decided to test his hypothesis that cowpox could be used to
protect humans against smallpox. Jenner injected a healthy
eight-year-old boy with cowpox obtained from a milkmaid’s
sore. The boy was moderately ill and recovered. Jenner theninjected the boy twice with the smallpox virus, and the boy did
not get sick.
Jenner’s discovery launched a new era in medicine, one
in which the intricacies of the immune system would become
increasingly important. Contemporary knowledge suggests
that cowpox was similar enough to smallpox that the antigen
included in the vaccine stimulated an immune response to
smallpox. Exposure to cowpox antigen transformed the boy’s
immune system, generating cells that would remember the
original antigen. The smallpox vaccine, like the many others
that would follow, carved a protective pattern in the immune
system, one that conditioned the immune system to move faster
and more efficiently against future infection by smallpox.
The term vaccination, taken from the Latin for cow
(vacca) was developed by Louis Pasteur(1822–1895) a cen-
tury later to define Jenner’s discovery. The term also drew
from the word vaccinia, the virus drawn from cowpox and
developed in the laboratory for use in the smallpox vaccine. In
spite of Jenner’s successful report, critics questioned the wis-
dom of using the vaccine, with some worrying that people
injected with cowpox would develop animal characteristics,
such as women growing animal hair. Nonetheless, the vaccine
gained popularity, and replaced the more risky direct inocula-
tion with smallpox. In 1979, following a major cooperative
effort between nations and several international organizations,
world health authorities declared smallpox the only infectious
disease to be completely eliminated.
The concerns expressed by Jenner’s contemporaries
about the side effects of vaccines would continue to follow the
pioneers of vaccine development. Virtually all vaccinations
continue to have side effects, with some of these effects due to
the inherent nature of the vaccine, some due to the potential
for impurities in a manufactured product, and some due to the
potential for human error in administering the vaccine.
Virtually all vaccines would also continue to attract
intense public interest. This was demonstrated in 1885 when
Louis Pasteur (1822–1895) saved the life of Joseph Meister, a
nine year old who had been attacked by a rabid dog. Pasteur’s
series of experimental rabiesvaccinations on the boy proved
the effectiveness of the new vaccine.
Until development of the rabies vaccine, Pasteur had
been criticized by the public, though his great discoveries
included the development of the food preservationprocess
called pasteurization. With the discovery of a rabies vaccine,
Pasteur became an honored figure. In France, his birthday
declared a national holiday, and streets renamed after him.
Pasteur’s rabies vaccine, the first human vaccine cre-
ated in a laboratory, was made of an extract gathered from the
spinal cords of rabies-infected rabbits. The live virus was
weakened by drying over potash. The new vaccination was far
from perfect, causing occasional fatalities and temporary
paralysis. Individuals had to be injected 14–21 times.
The rabies vaccine has been refined many times. In the
1950s, a vaccine grown in duck embryos replaced the use of
live virus, and in 1980, a vaccine developed in cultured human
cells was produced. In 1998, the newest vaccine technology—
genetically engineered vaccines—was applied to rabies. The
new DNAvaccine cost a fraction of the regular vaccine. Whilewomi_V 5/7/03 10:59 AM Page 569