In 1885, French chemist Louis Pasteur successfully treated a patient with his anti-rabies vaccine.

CNN: Monday,

Between 20, 000 and 40, 000 people in the U.S. receive the rabies vaccine each year, usually after being bitten by an animal.

CNN: Four shots enough to ward off rabies

For nearly a century after Louis Pasteur invented it in 1885, the rabies vaccine was made from ground-up animal brains and spinal cords.

CNN: Four shots enough to ward off rabies

They show no signs of rabies but are being treated with five doses of the rabies vaccine and rabies immune globulin, which gives the body antibodies to protect itself against the rabies virus.

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If there is concern about an exposure to rabies, prophylaxis consisting of rabies immune globulin (an injection that contains human antibodies against the rabies virus) and rabies vaccine (four injections over the course of two weeks) is recommended.

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The vaccine was created by taking a glycoprotein antigen from the rabies virus and inserting it into Vaccinia virus, the same one used for smallpox inoculation.

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The rabies virus causes brain swelling that is almost always fatal, but the vaccine is 100% effective when given in time.

CNN: Four shots enough to ward off rabies