How were vaccines first developed?

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The roots of modern vaccine development stretch halfway across the world to ancient China and India where, as early as the 10th century BC, people inhaled pus from smallpox blisters to inoculate themselves against the deadly disease. But it wasn't until 1796 that a country doctor from England named Edward Jenner formally vaccinated a child against the disease.

Rather than using pus or scabs from individuals infected with smallpox, he used pus from a similar, but less virulent pox disease called cowpox. He hypothesized this would protect against smallpox because milkmaids infected with cowpox never caught smallpox, even during epidemics. Two weeks after inoculating an eight-year-old boy, Jenner tried to infect him with smallpox. Nothing happened. Voila! The first successful vaccination. (Indeed, the word vaccine comes from the Latin word "vacca" for cow).

However, it would be nearly two centuries later before smallpox was eradicated worldwide (the last known case occurred in Somalia in 1977). Its banishment (except for samples held in Russian and American laboratories) has been heralded as one of the most significant medical achievements in history.

We've come a long way from Jenner's days, when "vaccines" were given by using a quill or ivory point to transfer the infected pus into a healthy person's skin. Today, safe, hair-thin needles deliver nearly painless injections, and some vaccines can be swallowed as a liquid or sprayed into the nose.

Today we have vaccines against childhood illnesses such as diphtheria, mumps, rubella and measles, which used to kill millions of children each year; against tetanus and rabies; and even against cancer. Some are designed to protect against infection in the first place, while others keep viruses or bacteria from spreading in the body. In all, more than 300 approved vaccines protect against 30 diseases. Not only have vaccines saved lives, they have changed the very world in which we live.
Lawrence T. Chiaramonte, MD
Allergy & Immunology
Originally, vaccination took place naturally through exposure to certain germs. If you studied the history of smallpox in biology, you will recall that the effective elimination of this deadly disease began when scientist Edward Jenner learned that by exposing people to a weak virus called cowpox, which was found on dairy farms, the body would produce immunity to the virulent smallpox as well. People who worked with cows enjoyed this immunity without medical intervention. By encountering cowpox while milking cows, their bodies were prompted to make antibodies specific for killing the invading bacteria.

The trick -- and it's a big one -- is to find a vaccine that provokes the production of antibodies without causing the disease. The original polio vaccine developed by Jonas Salk did this by using dead polio virus, but it was only partially effective and needed to be administered repeatedly. The more potent vaccine, created by Albert Sabin, used a live virus that had certain disease-producing components removed.
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Vaccines & Immunizations

Vaccines & Immunizations

Vaccines are commonly given to children in the form of a shot to help prevent serious diseases like measles and mumps. Vaccines are developed using either dead strains of a disease, weakened strains, or strains of a different dise...

ase. As adults, we receive flu vaccines or may need a booster of childhood vaccines to retain immunity. Travelers may receive vaccines either as a condition of entry to a country, or on recommendation of health officials. Generally there is little or no reaction to a vaccine, but in some cases the vaccine may cause an allergic reaction or a temporary, mild illness. Some vaccines are not safe for pregnant women, so it’s important to check with a healthcare professional.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.