As the latest crop of First Graders trundle off to school, I can’t help thinking back to my first year of school in Texas, and the badge of maturity I proudly wore on my left arm: the round scar produced by smallpox vaccination. It proved I was practically grown-up.
Today, kids no longer receive smallpox vaccinations. That’s because vaccination has eradicated the disease, which once killed millions.
But getting vaccinated is still a part of growing up. Canada’s National Advisory Committee on Immunization recommends that all children be immunized against polio, diptheria, tetanus, pertussis (whooping cough), Haemophilus influenzae type b (which caused meningitis), measles, mumps, rubella (German measles) and Hepatitis B.
Traditionally, most vaccinations have been given by injection, although a few can be given orally, as drops. Injections require trained technicians and special equipment, and most injectable vaccines must be refrigerated. These restrictions make mass immunization programs in developing countries difficult.
Last week, though, scientists at Stanford University Medical School reported that they were able to successfully vaccinate mice against the Hepatitis B virus simply by applying a solution of DNA and water to the mice’s skin. Dr. Paul Khavari, who led the group, says that in principle, the DNA solution could be put on a band-aid, spray or even in shampoo. Best of all, DNA can be stored indefinitely at room temperature.
To understand how this works, you need to understand how all vaccines work. Way back in 600 B.C., the Chinese attempted to immunize people against smallpox by putting smallpox material in their nostrils; modern immunization, however, got its start in 1796 when British physician Edward Jenner realized that people who had had cowpox, a similar but much milder disease that carries little risk of death or disfigurement, did not catch smallpox. He inserted material from cowpox sores into cuts he made on the arm of a healthy eight-year-old boy, who caught cowpox. When the boy was exposed to smallpox eight weeks later, he did not contract smallpox.
Vaccines trick the body’s immune system into treating them as a full-fledged infection. When the immune system detects foreign substances, called antigens, it creates antibodies or special white blood cells to attack them. Traditional vaccines consist of disease-causing organisms that have been either inactivated or killed. They trigger the immune system to produce antibodies, without causing disease. If full-strength bacteria or viruses of the same type enter the body in the future, the immune system has antibodies available to attack them immediately, destroying them before they can cause infection or disease.
With the Stanford approach, the DNA applied to the skin seeps into the hair follicles, causing them to produce the same antigens as the disease would, thus stimulating the immune system to make antibodies. The Stanford scientists will now carry out trials on larger animals and humans; if all goes well, the new type of vaccines may be available in just a few years.
The importance of immunization to public health is hard to overstate. Many diseases we no longer give a second thought were once major killers. Measles, for instance, which has been all but stamped out in North America–the U.S. recorded only 100 cases last year–still kills a million people every year, mostly in central Africa. Haemophilus influenzae type b meningitis and polio are two other diseases that have been nearly eliminated in this part of the world.
Despite these successes, some parents choose not to have their children vaccinated. The reasons range from the religious and philosophic (some feel government-mandated vaccination violates their rights) to concerns about vaccine safety and a feeling that, since we hardly ever see cases of the diseases for which vaccines exist, there’s no need to be vaccinated against them.
While it’s true vaccines pose a slight risk, that risk is far less than the risk of, say, driving the child to the doctor. In Canada, severe allergic reactions to vaccinations occur less often than once in every million doses of vaccine, and can almost always be effectively treated.
Meanwhile, the risk from the diseases vaccines prevent is very real, definite, and deadly. Stop vaccinations, and those diseases will return–as was proved in Great Britain in the 1970s. After a drop in whooping cough vaccinations in 1974, an epidemic of more than 100,000 cases, resulting in 36 deaths, occurred in 1978.
Vaccination is a wonderful tool in the fight against disease, but it must be used constantly and consistently. If it can also be made painless, all the better!
