“The Speckled Monster”—it sounds like something children imagine lurking under their beds. Or maybe it’s the sort of creature that eats New York in a bad horror movie. In reality, the speckled monster was Edward Jenner’s name for smallpox, a disease caused by a virus. Up until the last century, smallpox was a very real threat to children and adults alike.

Jenner was a doctor in the late 1700s. In those days smallpox killed 10 percent of the population. It caused one-third of all deaths among children.

Jenner noticed that milkmaids who were exposed to another virus—cowpox—did not catch smallpox, even when they were exposed to it. Cowpox is a virus that infects cows. It is similar to smallpox, but it is much less dangerous to humans.

Jenner formed a hypothesis. He believed that catching cowpox made people immune to the deadly smallpox virus. To test this, he infected people with cowpox and then exposed them to smallpox.

They did not get sick.

Jenner’s discovery led to the first widespread vaccination program. Today, smallpox has been eliminated. There are samples of the virus in laboratories, but nobody catches the disease naturally anymore, thanks to the vaccine.

Vaccines work by preparing your immune system to fight. Your immune system is like an army that defends your body from invaders. When it detects an intruder—like the chicken pox virus, for instance—it launches an attack.

Your immune system makes antibodies that are specially designed to destroy chicken pox. After the virus is gone, the antibodies stay in your body. If you ever come in contact with chicken pox again, your body is ready to destroy it quickly and easily.

When you get a vaccine, your immune system thinks it is facing a real enemy. It produces the same antibodies it would make if you had a disease. But with a vaccine, you don’t have the pain and risk of getting sick.

Jenner was lucky to find a virus that was like smallpox to use in his vaccine. For other diseases, scientists make vaccines using germs that have been killed or weakened so that they don’t cause illness.

Once in a while, even the dead or weakened viruses can make people sick. In the 1980s, scientists found a way around this problem using genetic engineering. They created “subunit” vaccines, which use only part of a virus instead of the whole thing. They leave out the parts that make you sick. Most vaccines used today are subunit vaccines.

Here in the United States, most children are vaccinated at a young age. We don’t worry much about dangerous diseases like diphtheria, mumps and polio.

In poorer countries, however, these diseases are still a serious threat. The World Health Organization says that in 2002, about 2.1 million people died from diseases that could have been prevented by vaccines.

The most obvious reason for this is that people in poor countries can’t afford vaccines. Also, traditional vaccines must be refrigerated until they are used, and trained healthcare workers must give them out. In rural areas, where people live far apart and doctors are scarce, vaccines can be difficult to store, transport and dispense.

Another problem is that vaccines don’t exist for some of the diseases that are common in poorer countries. The biggest drug companies are based in wealthy countries like the U.S. They tend to focus their vaccine research on diseases that happen where they live.

Researchers at ASU are trying to develop new and better vaccines. Some are trying to develop vaccines for diseases we haven’t been able to prevent before. Others are working to make existing vaccines safer, cheaper, and more efficient. This will make them easier to deliver to less-developed countries, as well.

These scientists have to find creative new ways to produce and deliver vaccines. They are not afraid of trying ideas that might seem bizarre— like putting vaccines into tomato plants or Salmonella bacteria.