Ask the doctor
Q. Fancy new technologies keep appearing in medicine. Are there any innovative new kinds of vaccines?
A. There sure are. Vaccines are one of the greatest inventions in history. The smallpox vaccine campaign conducted by the World Health Organization eradicated the disease from the face of the earth by 1980. How much good did that do? From 1900 to 1980, 300 million people died from smallpox. Since 1980, not one death.
All vaccines for infectious diseases stimulate the immune system to attack a specific microbe. The vaccine typically includes a killed or weakened microbe, or a protein from the microbe. When the vaccine enters the body, the immune system “sees” and remembers it. Then, if the real microbe enters the body later in life, the primed immune system attacks and eradicates it.
As for new approaches, scientists are developing skin patches and inhaled aerosols to deliver vaccines, and genetically engineering plants to make vaccines. Work is under way on vaccines that reduce the damage done by infections people already have, and vaccines against some non-infectious illnesses, such as certain cancers and high blood pressure.
Instead of injecting a protein from a microbe, as traditional vaccines do, a new type of vaccine injects the DNA that directs the making of the protein. The DNA enters some of a person’s cells, and the cells then make the protein. One virtue of such DNA vaccines is that, in contrast to typical vaccines, they don’t require refrigeration — which is important in hot, poorly electrified developing countries.
Some microbes (like influenza virus and HIV) keep changing their protein “coats.” Those protein coats are the usual target of vaccines, and it’s hard to hit a moving target. So scientists are creating vaccines that cause the immune system to make “neutralizing” antibodies against the parts of the protein coat that do not keep changing. If this approach works, for example, we might be able to avoid having to get a new flu shot every year.
How did vaccines begin? In the mid-18th century, an apprentice surgeon named Edward Jenner was studying dairy workers exposed to cows that suffered from a disease called cowpox. Jenner noticed that, while the workers might become mildly ill, thereafter they didn’t get smallpox. His curiosity piqued, Jenner took pus from a young woman with cowpox and scratched it on the skin of healthy children and adults: it protected them during the next outbreak of smallpox. Jenner had discovered vaccines. While the spirit of innovation is alive and well in the modern vaccine era, it will be hard to match the impact of that first innovation by a curious young apprentice surgeon. It changed our world.
— by Anthony L. Komaroff, M.D.
Editor in Chief, Harvard Health Letter
Image: © gorodenkoff/Getty Images
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