Vaccinations

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Introduction

Vaccines are liquid solutions containing dead or weakened forms of infectious microbes that are injected into the body to produce immunity from disease. Vaccinations typically work by inducing the immune system to generate antibodies that attack certain viruses or bacteria. Because the microorganisms contained in vaccines are weak or inactive, their presence can strengthen the body's natural defenses without causing illness. Vaccines also enable the immune system to react quickly and effectively when threatened by disease in the future.

The concept of immunization through inoculation is considered to be one of the most significant advances in scientific history. Western medicine's introduction to the practice most likely occurred in the eighteenth century, when traveling British aristocrat Mary Montagu reported her observations of Turkish children being injected with pus from smallpox victims. Most of these children would contract a mild version of the illness yet later retain a lifelong immunity to it. Similarly, in the United States, Puritan clergyman Cotton Mather learned about vaccination from his African slave Onesimus, who claimed that he had been inoculated with smallpox pus and had never caught the disease. Initially rejected by most Western doctors as a dangerous and barbarous practice, vaccination gained wide support at the turn of the nineteenth century when English physician Edward Jenner created a new smallpox vaccine made from the relatively mild cowpox virus.

During the twentieth century, scientific innovations led to the development of improved vaccines for several infectious diseases. Eventually, as a result of widespread immunizations, previously devastating illnesses such as diphtheria, whooping cough, and tetanus became rare. Smallpox was declared eradicated as a naturally occurring illness in 1980, and polio is expected to be abolished globally during the first decade of the twenty-first century. Most health experts also believe that the eradication of measles is possible.

Despite the general improvement in public health that has resulted from the practice of immunization, the issue of mandatory vaccination has become somewhat controversial in recent years. In the United States, most state laws require children to receive several doses of ten different viral and bacterial vaccines before entering kindergarten. As is the case with all medicines, vaccines can cause side effects in some people, including soreness at the injection site, fever, aches, and fatigue. Severe adverse effects, such as allergic reactions, convulsions, shock, and death are also possible but are reported to be statistically rare. It is these adverse reactions, along with the possibility that some reactions can lead to longterm health problems in certain individuals, that have stirred debate during the past decade.

Vaccination critics argue that the serious side effects associated with vaccines have been underreported and rarely researched. Several analysts have conducted studies that suggest that vaccines are a causal factor in chronic disorders such as asthma, autism, epilepsy, diabetes, learning disabilities, immune system dysfunction, and mental retardation. "Instead of epidemics of measles and polio, we have epidemics of chronic autoimmune and neurological disease," states Barbara Loe Fisher, cofounder of the National Vaccine Information Center in Vienna, Virginia. "In the last twenty years rates of asthma and attention-deficit disorder have doubled, diabetes and learning disabilities have tripled, chronic arthritis now affects nearly one in five Americans and autism has increased by 300 percent or more in many states." Fisher and her supporters claim that children with a family history of immune system disorders or other genetic vulnerabilities are more likely to experience severe vaccine reactions that could result in developmental disabilities or chronic illnesses. Vaccine critics contend that these children should not be forced to submit to a "one size fits all" immunization policy—an approach that ignores individual differences to fulfill legal public health requirements. Fisher and others insist that informed parental consent is preferable to legal mandate as a standard for national vaccination policy.

Most public health experts maintain that immunization critics have exaggerated the potential harms of vaccines and argue that the benefits of vaccination greatly exceed the dangers posed by adverse effects. In examining the risks of disease versus the risks of vaccine, the Centers for Disease Control and Prevention (CDC) reports that one out of every three thousand people who contract measles dies, and one out of every three hundred mumps victims develops encephalitis. However, only one out of every million people given the measles/mumps/rubella (MMR) vaccine develops encephalitis or a severe allergic reaction. In addition, several recent scientific studies have found no conclusive evidence linking vaccines to chronic illnesses and developmental disorders. In 2001, for example, the U.S. Institute of Medicine (IOM) conducted a review of current data and rejected claims of a causal relation between the MMR vaccine and autism. "The fact is that a child is far more likely to be seriously injured by one of these diseases than by any vaccine," the CDC states in a report published on its website. "While any serious injury or death caused by vaccines is too many, it is also clear that the benefits of vaccination greatly outweigh the slight risk, and that many, many more injuries and deaths would occur without vaccinations." Allowing individuals to decide if and when their child should be vaccinated, medical experts argue, would lower immunization rates and increase the possibility of disease outbreaks that could become epidemics. The CDC maintains that continuing research "will reduce even further the already low risk of serious vaccine-related injury."

Nevertheless, many observers remain concerned about the side effects of vaccines, partly because the recent immunization safety studies have methodological limitations. For example, the scientific experts who took part in the 2001 IOM study warned that they could not absolutely rule out that the MMR vaccine "may contribute to autistic spectrum disorders" because epidemiological reviews [epidemiology is the study of diseases and their spread] lack the precision to assess rare adverse effects. Furthermore, as Seattle immunologist Gerald T. Nepom admits, "in theory . . . a link between vaccines and autoimmune disease is biologically plausible." So, although no connection between vaccines and chronic illness has been established, neither is there evidence that completely disproves such a connection, critics point out.

Reflecting the growing skepticism about vaccine safety is the recent debate about the distribution of the smallpox vaccine—one of the riskiest of the licensed vaccines—in the United States. Routine smallpox vaccinations ended in 1972, when immunologists determined that the health risk of the vaccine had exceeded the risk of contracting the virus. The last case of smallpox in the United States had occurred in 1947, and since the vaccine is associated with a certain number of serious side effects—including disfiguring rashes, encephalitis, neurological damage, and death—experts concluded that the virtual eradication of the disease had made smallpox vaccination an unnecessary hazard. However, after the September 11 terrorist attacks on the World Trade Center and the Pentagon and the subsequent anthrax mailings during the fall of 2001, the American public became increasingly concerned about the possibility of smallpox-wielding bioterrorists striking the United States. Since many Americans have never received the vaccine, and since those who were vaccinated prior to 1972 may no longer be immune, a smallpox terrorist attack could be catastrophic. "Smallpox mortality rates in the unvaccinated top 50 percent," reports Los Angeles Times staff writer Edmund Sanders. "On the other hand, if the government resumed smallpox vaccines for the entire U.S. population today, an estimated 300 citizens could die of complications and thousands more would have serious health problems."

In October 2001, the U.S. government contracted with Acambis and Acambis-Baxter Pharmaceuticals to produce enough smallpox vaccine to inoculate every American by the beginning of 2003 or soon thereafter. However, in June 2002, the federal Advisory Committee on Immunization Practices (ACIP) assessed the risk of a smallpox attack as low and recommended against vaccinating the general population. The ACIP instead endorses vaccination for selected emergency medical personnel who can be called upon to respond in case of a bioterrorist attack. If such an event occurs, these personnel would distribute the vaccine only to those who come into direct contact with infected people. This technique, known as "ring vaccination," helped health officials tackle naturally occurring global outbreaks of smallpox in the mid-twentieth century.

Some analysts, however, fear that the ring vaccination strategy would be less effective against a deliberate biological attack, particularly in countries with highly mobile populations. "For example," asks Sanders, "if a terrorist infected with smallpox traveled on New York City subways for a week during rush hour, how would health officials be able to track down all potential contacts"" With such a scenario in mind, some public health officials advocate a gradual resumption of smallpox vaccinations for all Americans—excepting small children, who are more susceptible to health complications. As the controversy over the smallpox vaccine reveals, balancing the risk of vaccinations against the risk of infectious epidemics can be a trou- blingly complex issue. For the time being, Health and Human Services secretary Tommy G. Thompson has decided to accept the ACIP recommendation of selective smallpox vaccination for medical personnel, establishing this proposal as official U.S. policy. The authors in.....

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