Beginning in the weeks before your birth, a special miracle takes place inside your body. Specifically, your immune system is encoded with a basic message telling it whether each cell is “self,” and therefore friendly, or “not self,” and therefore a possible danger.
This important piece of information is key in the development of your body’s defense against disease. From this point on, any virus or bacterium that enters your body is seen as “not self” and the immune system rallies various defenses against it. Part of this defense involves “reading” the surface of the invading cell and calling for the reproduction of specific cells — antibodies — designed to fight that invader. If this works well, the foreign substance is destroyed and the new antibodies hang around in case it ever returns.
This important attack and counterattack happens nearly every day inside your body. Unfortunately, left to nature, the immune system sometimes comes up with too little, too late. You may suffer an uncomfortable illness or, with more virulent diseases, even death.
In this century, however, medical science has found ways to artificially “turn on” disease-fighting cells by way of vaccination, or immunization. Immunization uses the body’s natural defense system to bring about immunity, except that the innoculant, that is, the organism introduced, is first made as harmless as possible.
Traditionally, immunization has been accomplished through two major avenues, live and killed vaccines. Those from live sources are made safe by treating them to make the disease-producing cells helpless while leaving enough material to promote antibody formation.
Immunizations can also be developed to promote antibody formation from killed sources. Killed-organism immunizations are safer, but not always as effective as their live counterparts, and may require “booster” shots. Boosters are given some time after the first shot to increase immunity.
Immunization serves two important purposes. First, and most obvious, it protects each individual against a specific disease. But, in addition, it can serve to protect a much larger population by reducing the number of disease carriers. In some cases this number becomes so small that the tiny disease-causing organism is rendered extinct.
Widespread immunization of children and adults has eliminated smallpox, once the curse of the world, from the face of the earth. The last recorded case was in Africa in 1977, and now the bacterium exists only in a few laboratories — a necessary precaution should it unexpectedly recur.
Polio has been similarly driven out, at least in the United States. Just 40 years ago, parents lived in fear of polio. Thousands of children died or were crippled by the virus. In 1990 there were no reported cases of the disease in the United States — not a single one.
Similar progress has been made against tetanus, typhoid, diphtheria, mumps, whooping cough, and measles, although in recent years the number of cases of measles has increased dramatically, especially among college students. This is why some experts now recommend that children receive a second measles shot.
Why can’t we create immunizations against all diseases? First, some diseases are clever enough not to cause a strong natural immune response from the human body, so vaccines would do little to help fight them. Others, such as AIDS, quickly disarm whatever the body brings against them by changing the mechanisms of the immune system itself.
In some illnesses, such as influenza, the problem is combating the virus’ ability to “change its clothes.” It is relatively easy to make a vaccine against an influenza raging this year, but by next year the virus will have changed slightly. Whatever antibodies are “switched on” now may not figure into the battle in 1992.
What illnesses will we tackle next? Obviously, the rush to find a vaccine to combat AIDS occupies many laboratories throughout the world. Recent tests show promise, although no immunization is likely to be available for general use in the near future.
Chicken pox is a life-threatening disease for those with a compromised immune system, such as children with cancer, or AIDS patients. In addition, it re-emerges in many people as shingles, a painful condition for which there is only minimal treatment. An experimental vaccine is already being used, and a better one may be available soon.
Cytomegalovirus causes an estimated 5,000 cases of birth defects, mainly retardation, each year. Researchers are close to developing an effective vaccine that might one day be given to women and girls to protect their unborn babies. An inoculation against the herpes virus, another cause of birth defects, might also be available soon.
Many other illnesses for which immunizations are being created are more common in developing countries, where poverty, poor sanitation, and large population give rise to the spread of infection. Disease being tackled inclkude streptococcus, leprosy, dengue fever, and encephalitis.
The recent explosion of information about viruses, much of it a result of research centered around the virus that causes AIDS, is producing exciting ways to improve vaccines. Scientists are experimenting with ways to artificially encode cells with antibody-triggering messages and with methods of removing from a virus the portion of its genetic structure that allows it to reproduce itself. This last technique, already used successfully with animal vaccines, allows inoculation with strong and effective live viruses, but without the risk of causing a true infection.
Perhaps the most striking thing about future immunizations is the move toward easier ways to receive vaccines. Currently, nasal “injection” immunizations are being developed for measles, influenza, rubella, and some respiratory diseases. These would require the user to inhale the vaccine. In addition, scientists are using new high-tech methods to create an immunization that would allow a single shot to convey immunity to four or more diseases simultaneously.
Who knows? The children of the next decade may get a quick spray and a single injection and be protected from disease for life!