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Typical Disease Prevention


Every day, it seems, there are news reports or rumors suggesting that vaccines may cause death or autism or myriad other unfortunate results. And as they hold their children to receive shots or vaccine boosters, parents know that their child is at some risk. If I were a parent, I would be petrified at that doctor's appointment. But I would still make sure that my child was vaccinated because I believe the benefits of a life without fear of polio or smallpox or tetanus, for example, are well worth the risks.

8325vaccines_shot.tifcxd SCIENCE PHOTO LIBRARY

That's saying something. When I was a baby, I nearly died from my third DPT (diptheria-pertussis-tetanus) shot, and it's only because I turned blue while still in the doctor's office that I'm still alive. Given the dangers--some real and some imagined--it's sometimes difficult to remember that vaccinations, while not perfect, have saved hundreds of millions of lives from plagues that once swept the world.

The concept of injecting a modified version of an infectious agent into people to prevent them from later contracting a full-blown case of the disease sounds counterintuitive at first, but even the most ancient of civilizations must have observed that people couldn't get smallpox twice. That's because the human immune system has a long memory, making its response to a repeat attack especially efficient.

We now know that vaccines work by tricking the immune system into thinking it is under attack by foreign organisms. By using dead or attenuated disease-causing agents, or toxins isolated from them, vaccines goad the body into initiating a full-fledged immune response.

Macrophages, lymphocytes, and other frontline soldiers rush to the body's defense; eventually, B cells generate antibodies that tag or neutralize the "invaders." These B cells and their antibodies are quite specifically tuned to the structure of the particular antigen, and special B cells, known as "memory B cells," circulate in the blood long after the initial attack. If the same antigen presents itself later, the body's immune reaction is much quicker and more brutal; the tuned B cells proliferate and generate clouds of antibodies, which lead to the destruction of the disease-causing agent before symptoms can appear.

Early researchers didn't know the inner workings of the immune system, but immunity against disease had been observed long before Edward Jenner "discovered" vaccines. Some of the earliest attempts to artificially produce such immunity occurred in China in the 16th century, where dried powdered smallpox scabs were inhaled nasally to prevent the disease. In India, physicians put smallpox scabs on the scarified skin of healthy people to prevent them from becoming ill.

These crude techniques for preventing smallpox were mostly successful. They spread to Istanbul, where they came to the attention of Lady Mary Wortley Montague (1689-1762), wife of the British ambassador to Turkey. Lady Montague, a smallpox survivor, was desperate to inoculate her son against the disease because she was more terrified of smallpox than of the vaccination. She insisted that her son be "variolated," as the practice was called at the time; she soon followed suit with her daughter. When the Princess of Wales had her children treated with smallpox scabs, vaccination became socially acceptable in England.

In the U.S., Jenner (1749-1823) noticed that people who milked cows didn't get smallpox, though they did contract cowpox, a similar ailment with much milder symptoms. In 1796, Jenner tested a hunch by taking pus from a milkmaid's cowpox blisters and injecting it into a boy. After the boy recovered from cowpox, Jenner intentionally injected the boy with smallpox, and the boy did not catch the often fatal disease.

Jenner's discovery, used in a major immunization campaign in the mid-20th century, is still the only viable preventative treatment for smallpox. By 1980, modernized versions of Jenner's vaccine had effectively eradicated smallpox from the world, except for a few laboratory stocks.

Jenner's work also led to vaccines for many other scourges. There are currently 21 vaccine-preventable diseases, among them meningitis, hepatitis A and B, pneumonia, influenza, measles, and polio; scientists are working to add more to that list. Vaccine manufacturers still face a number of challenges in bringing a safe supply of existing vaccines to the public, however, as the recent crisis with the annual flu vaccine demonstrated (C&EN, Nov. 15, 2004, page 29).—LINDA RABER


The Top Pharmaceuticals
That Changed The World
Vol. 83, Issue 25 (6/20/05)
Table Of Contents


First introduced

  • 1798, smallpox; 1885, rabies; 1897, plague; 1923, diphtheria; 1926, pertussis; 1927, tuberculosis; 1927, tetanus; 1935, yellow fever; 1955, injectable polio vaccine; 1962, oral polio vaccine; 1964, measles; 1967, mumps; 1970 rubella; 1981, hepatitis B

In clinical trials

  • Vaccines for West Nile virus, avian flu, herpes virus (women), tuberculosis (recombinant)

In development

  • Vaccines for cytomegalovirus, group B streptococcus, chlamydial and other sexually transmitted infections, among others

Did you know that the word "vaccination" is derived from "vacca," Latin for cow, because Jenner inoculated humans with cowpox to prevent smallpox?