By Lt. Col. Brad S. Winterton, 1st Air Force Epidemiologist
/ Published September 16, 2009
TYNDALL AIR FORCE BASE, Fla -- Two hundred years ago, the average life expectancy was about 40 years. Today, it is nearly 80 years. That doubling of life expectancy can be almost entirely attributed to just two things: improved sanitation and immunizations. All other medical advances combined don't even begin to come close to the effects of those two.
The success of vaccines has become their biggest stumbling block. Only the very oldest Americans have seen family members die of diphtheria, measles, mumps, smallpox, tetanus, or whooping cough. I remember my father telling me that his greatest childhood fear was contracting polio and spending the rest of his life in an iron lung; however, we no longer see children or adults crippled or dead from polio in our country. Thanks to vaccines, we are insulated from most of the illness and death that was part of everyday life for almost the entire history of mankind (and still is in many parts of the world). Those who decry vaccines as dangerous or even as an evil conspiracy are able to do so precisely because of the success of vaccines; without vaccines there is a very high probability many of those individuals would not have lived past age 10 and, therefore, would not have had the opportunity to complain about vaccines.
Is immunization 100 percent effective? No. A few people can receive multiple doses of a vaccine and never develop immunity to that disease. Are vaccines 100 percent safe? No. No medical procedure is 100 percent safe. A few people have negative reactions to vaccines that cause serious illness or even death. However, given the choice of having a quarter to half of all children die before reaching adolescence (as still happens today in countries where sanitation is poor and vaccines are not available) versus having one child in a million suffer a serious negative effect of a vaccine, the choice is pretty obvious. It is a genuine tragedy for that one; it is literally lifesaving for the other hundreds of thousands.
Immunization is largely an individual choice. Those who do not wish to be immunized can refuse based on religious or philosophical objections. However, such individuals are still protected by the very vaccines they refuse - by being surrounded with people who are immunized; it's called "population immunity." Once a certain percentage of the population is immune, diseases can no longer circulate because they can't find enough susceptible individuals to propagate effectively.
For most diseases, population immunity is achieved when about 80 percent of the population is immune. If the level dips below that, the disease has enough susceptible hosts to circulate again. But even when population immunity is reached, unimmunized individuals are still at risk and can (and often do) contract the disease when exposed to an active case.
This year, we face a new influenza virus circulating across the globe. We know it as H1N1, novel, or "swine" flu. It spreads easily from person to person but, gratefully, causes mostly non-life-threatening illness, similar to seasonal flu. Still, seasonal flu sickens about 10 percent of the population and causes an estimated 36,000 deaths in the U.S. every year. The H1N1 virus is expected to sicken more than 100 million Americans over the next two years, and could take the lives of 100,000. In addition, there is always a chance H1N1 could mutate to cause much more serious illness and much greater loss of life.
In response to this new flu, government agencies and vaccine manufacturers have partnered to prepare a vaccine against it. U.S. and European companies have been manufacturing seasonal flu vaccines for many years. The process is well developed and well understood, and generally takes about six months from beginning to end. This year has been a challenge because the companies making the H1N1 flu vaccine are the same ones that also make the seasonal flu vaccine. They cranked up their capacity and completed the seasonal flu vaccine as quickly as possible, so they could then turn their efforts and resources to the H1N1 vaccine. Seasonal flu vaccine is available now across most of the U.S. and there is plenty for everyone who wants it. The H1N1 flu vaccine should begin to be available by mid-October; however, because there may not be enough for everyone, health officials have identified those groups who should receive first priority for the vaccine.
The Centers for Disease Control and Prevention strongly recommends the H1N1 vaccine for pregnant women, parents of infants less than 6 months old, children and young adults 6 months to 24 years, and adults under 65 with underlying illness that places them at higher risk for complications from flu. These CDC recommendations are based entirely on what has been observed with this virus so far. A disproportionately high percentage of the serious illness and death due to H1N1 has been among pregnant women. It also affects children and young people up to age 24 more than adults, and causes more serious illness in children, young people, and adults with underlying illness. Adults over age 65 seem to have some immunity to H1N1, probably from exposure to a similar flu virus in the 1930s and/or early 1940s.
I believe in immunization. I believe Edward Jenner, the doctor who developed the very first vaccine--against smallpox 200 years ago--was inspired to do what he did. I believe vaccines are a great blessing to those who live in our day, allowing us to avoid many of the things that routinely killed our ancestors and their children. Jenner's vaccine led to the eradication of smallpox from the face of the earth and the development of other vaccines against diseases such as anthrax, chicken pox, diphtheria, hepatitis A and B, measles, rubella, whooping cough, yellow fever, and now even some types of cancer.
The Salk and Sabin polio vaccines led to the near-eradication of polio; only Afghanistan, Pakistan, India and Nigeria still have circulating polio virus, and intense efforts are underway to complete the eradication process there. Once polio is gone, the World Health Organization plans to focus on the global eradication of measles. Vaccines against malaria and other illnesses are in development, will further benefit mankind, and may lead to the eradication of even more diseases.
Vaccine-preventable illnesses have caused unimaginable suffering and death; now most of them seem like ancient history. I will be in line, with my family in tow, to receive our shots as they become available, including the H1N1 vaccine.