Sabin, Albert WORLD OF MICROBIOLOGY AND IMMUNOLOGY500•
the virus and thus did not develop a natural immunity. As a
result, polio became an epidemic disease and spread quickly
through communities to other children without immunity,
regardless of race, creed, or social status. Often victims of
polio would lose complete control of their muscles and had
to be kept on a respirator, or in a low-pressure iron lung, to
help them breathe.
In 1936, Sabin and Peter K. Olitsky used a test tube to
grow some poliovirus in the central nervous tissue of human
embryos. Not a practical approach for developing the huge
amounts of virus needed to produce a vaccine, this research
nonetheless opened new avenues of investigation for other sci-
entists. However, their discovery did reinforce the mistaken
assumption that polio only affected nerve cells.
Although primarily interested in polio, Sabin was
“never able to be a one-virus virologist,” as he told Donald
Robinson in an interview for Robinson’s book The Miracle
Finders. Sabin also studied how the immune systembattled
viruses and conducted basic research on how viruses affect
the central nervous system. Other interests included investi-
gations of toxoplasmosis, a usually benign viral disease that
sometimes caused death or severe brain and eye damage in
prenatal infections. These studies resulted in the develop-
ment of rapid and sensitive serologic diagnostic tests for
the virus.
During World War II, Sabin served in the United States
Army Medical Corps. He was stationed in the Pacific theater
where he began his investigations into insect-borne encephali-
tis, sandfly fever, and dengue. He successfully developed a
vaccine for dengue fever and conducted an intensive vaccina-
tionprogram on Okinawa using a vaccine he had developed at
Children’s Hospital of Cincinnati that protected more than
65,000 military personnel against Japanese encephalitis. Sabin
eventually identified a number of antigenic (or immune
response-promoting) types of sandfly fever and dengue
viruses that led to the development of several attenuated (avir-
ulent) live-virus vaccines.
After the war, Sabin returned to the University of
Cincinnati College of Medicine, where he had previously
accepted an appointment in 1937. With his new appointments
as professor of research pediatrics and fellow of the Children’s
Hospital Research Foundation, Sabin plunged back into polio
research. Sabin and his colleagues began performing autopsies
on everyone who had died from polio within a four-hundred-
mile radius of Cincinnati, Ohio. At the same time, Sabin per-
formed autopsies on monkeys. From these observations, he
found that the poliovirus was present in humans in both the
intestinal tract and the central nervous system. Sabin dis-
proved the widely held assumption that polio entered humans
through the nose to the respiratory tract, showing that it first
invaded the digestive tract before attacking nerve tissue. Sabin
was also among the investigators who identified the three dif-
ferent strains of polio.
Sabin’s discovery of polio in the digestive tract indi-
cated that perhaps the polio virus could be grown in a test tube
in tissue other than nerve tissue, as opposed to costly and dif-
ficult-to-work-with nerve tissue. In 1949, John Franklin
Enders, Frederick Chapman Robbins, and Thomas HuckleSweller grew the first polio virus in human and monkey non-
nervous tissue cultures, a feat that would earn them a Nobel
Prize. With the newfound ability to produce enough virus to
conduct large-scale research efforts, the race to develop an
effective vaccine accelerated.
At the same time that Sabin began his work to develop
a polio vaccine, a young scientist at the University of
Pittsburgh, Jonas Salk, entered the race. Both men were enor-
mously ambitious and committed to their own theory about
which type of vaccine would work best against polio. While
Salk committed his efforts to a killed polio virus, Sabin openly
expressed his doubts about the safety of such a vaccine as well
as its effectiveness in providing lasting protection. Sabin was
convinced that an attenuated live-virus vaccine would provide
the safe, long-term protection needed. Such a vaccine is made
of living virus that is diluted, or weakened, so that it spurs the
immune system to fight off the disease without actually caus-
ing the disease itself.
In 1953, Salk seemed to have won the battle when he
announced the development of a dead virus vaccine made
from cultured polio virus inactivated, or killed, with
formaldehyde. While many clamored for immediate mass
field trials, Sabin, Enders, and others cautioned against mass
inoculation until further efficacy and safety studies were con-
ducted. Salk, however, had won the entire moral and financial
support of the National Foundation for Infantile Paralysis,
and in 1954, a massive field trial of the vaccine was held. In
1955, to worldwide fanfare, the vaccine was pronounced
effective and safe.
Church and town hall bells rang throughout the country,
hailing the new vaccine and Salk. However, on April 26, just
fourteen days after the announcement, five children in
California contracted polio after taking the Salk vaccine. More
cases began to occur, with eleven out of 204 people stricken
eventually dying. The United States Public Health Service
(PHS) ordered a halt to the vaccinations, and a virulent live
virus was found to be in certain batches of the manufactured
vaccine. After the installation of better safeguards in manufac-
turing, the Salk vaccine was again given to the public and
greatly reduced the incidence of polio in the United States. But
Sabin and Enders had been right about the dangers associated
with a dead-virus vaccine; and Sabin continued to work
toward a vaccine that he believed would be safe, long lasting,
and orally administered without the need for injection like
Salk’s vaccine.
By orally administering the vaccine, Sabin wanted it to
multiply in the intestinal tract. Sabin used Enders’s technique
to obtain the virus and tested individual virus particles on the
central nervous system of monkeys to see whether the virus
did any damage. According to various estimates, Sabin’s
meticulous experiments were performed on anywhere from
nine to fifteen thousand monkeys and hundreds of chim-
panzees. Eventually, he diluted three mutant strains of polio
that seemed to stimulate antibody production in chim-
panzees. Sabin immediately tested the three strains on him-
self and his family, as well as research associates and
volunteer prisoners from Chillicothe Penitentiary in Ohio.
Results of these tests showed that the viruses producedwomi_S 5/7/03 8:20 AM Page 500