The Journal of the American Medical Association has written, “Vaccines are among the greatest achievements of biomedical science and public health, stimulating protective immune responses against acute and chronic infectious diseases as well as some that result in cancer.”

It has long been known that a group of people – all exposed to a disease – will not all get the same degree of illness, and some will not get it at all. The reason for this is related to the body’s immune system. Studies have found that the system can be weakened by stresses, diseases like HIV, lack of sleep, and drugs. Conversely, the system may be strengthened through exercise, eating a healthy diet, and avoiding tobacco and excessive alcohol consumption.

The immune system can also be “tricked” into resisting a particular disease by exposure to it. This can be done by actually getting the illness through contact, or through immunization. This is a process by which a mild form of the disease is introduced into the body using a vaccine, usually administered by injection, but can also be given orally or inhaled. When this “trick” occurs, the body produces antibodies that are utilized to fight that particular infection if another contact happens.

Smallpox was the first disease for which a vaccine was tried. Unsuccessful experiments to come up with a prevention date back to 10th century China. Over the ages, that illness has killed billions of people. It is highly contagious, caused by the Variola virus. The disease was originally known as the “pox or red plague.” The term smallpox was first used in the 15th century to distinguish it from the large pox, syphilis.

Smallpox holds a unique place in American history. It was responsible for the decimation of many Native American tribes through exposure from European settlers.

The first successful use of smallpox vaccine was in 1796, when an English physician, Edward Jenner, inoculated a boy, preventing him from getting the disease. The doctor used a scalpel to scratch some infected material (which he named “vaccine’) from a person with cowpox, a mild form of smallpox, under the boy’s skin.

One of the deadliest of diseases known to humans, smallpox is also the only one to have been fully eradicated by vaccination. The last known case of the illness in the world occurred in 1977.

Vaccine development for other infections started in earnest in the late 19th century. Almost all of the early work focused on bacterial caused diseases, such as cholera and typhoid, because little was known of viruses. One exception was rabies, a fatal viral illness caused by a bite from an infected animal. In 1885, Louis Pasteur successfully immunized a boy using weakened material from a dead rabbit. The early 1900s saw many new vaccines, such as diphtheria, tuberculosis and pertussis (whooping cough). Later in that century, vaccines for viral illnesses like influenza, polio, measles, mumps and many others followed. Today, although none of these diseases have been completely eliminated, their occurrence has been drastically reduced.

There are still many other infections for which vaccines have been developed, but to be effective in eliminating a disease in any population, vaccinations for a particular illness must be given to a large percentage of the people.

For instance, measles had been almost non-existent in this country for many years until a recent outbreak, starting in California, quickly spread to many states. It did so because some children and young adults had not yet been vaccinated.

There have been multiple studies showing that measles vaccine is safe and poses little, if any threat for serious side-effects. However, there is a very active group of parents who are convinced that measles in particular and vaccines in general cause various maladies like autism or multiple sclerosis, even though no evidence exists. They resent and resist laws that mandate vaccinations, insisting that they know what’s best for their children. The problem with this rationale is that it puts not just their kids at risk, but everyone else who is unvaccinated. Measles can lead to serious complications including pneumonia, deafness and encephalitis (swelling of the brain).

The flu vaccine given every year is multi-variant, which means it is designed to fight several different forms of the disease. Sometimes, the virus mutates into a different form between the time the vaccine is developed early in the year and it is available later in the fall. That’s what happened last year, and as a result, the vaccine was largely ineffective.

The recent outbreak of Ebola in West Africa shows us how easily a deadly virus can spread. A vaccine for it has been developed and is now in early testing, showing some promise.

The world is a safer place because of vaccines. Through education and the tireless work of many doctors, nurses and volunteers, most infectious diseases, known and yet to come, can be limited or even eliminated.

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Marcus Goodkind of Tuckasegee, a retired aerospace engineer, worked with the National Aeronautics and Space Administration as a manager at Kennedy Space Center on all the manned programs from Mercury to Shuttle, including Apollo 11, the first manned lunar landing.