Right: this Australian woman, June Middleton, who died in 2009, contracted polio at the age of 22 and spent more than 60 years in an "iron lung", a machine that "breathed" for its paralysed occupant.
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Background information
Note: much of the following information is abbreviated from the Wikipedia entry titled 'Vaccination'. The full text of this entry can be found at http://en.wikipedia.org/wiki/Vaccination
Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen (disease-causing agent).
Vaccines can prevent or reduce the severity of diseases that result from infection. The effectiveness of vaccination has been widely studied and verified; for example, the influenza vaccine, the HPV vaccine, and the chicken pox vaccine have all been shown to work extremely well in guarding against infection.
Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the restriction of diseases such as polio, measles, and tetanus from much of the world.
The active agent of a vaccine may be forms of the causative pathogens, or purified components of the pathogen that have been left intact but inactivated (non-infective) or attenuated (treated so that their capacity to infect has been reduced).
Exposure to non-harmful variants of disease-causing agents stimulates the body's immune response, so that when harmful disease-causing agents are encountered the body will be able to combat them.
This process of artificially inducing immunity, in an effort to protect against infectious disease, works by 'priming' the immune system with an 'immunogen', that is, a substance that is able to provoke an adaptive immune response. Stimulating immune responses with an infectious agent is known as immunisation.
Adjuvants and preservatives
Vaccines (the immune-boosting cocktail injected into the subject) typically contain one or more adjuvants, used to boost the immune response. Tetanus toxoid, for instance, is usually adsorbed onto alum. This presents the antigen in such a way as to produce a greater action than the simple tetanus toxoid suspended in water. People who get an excessive reaction to adsorbed tetanus toxoid may be given the simple vaccine when time for a booster occurs.
In the preparation for the 1990 Gulf campaign, Pertussis vaccine was used as an adjuvant for Anthrax vaccine. This produces a more rapid immune response than giving only the Anthrax, which is of some benefit if exposure might be imminent.
Vaccines may also contain preservatives to prevent contamination with bacteria or fungi. Until recent years, the preservative thiomersal was used in many vaccines that did not contain live virus. As of 2005, the only childhood vaccine in the United States that contains thiomersal in greater than trace amounts is the influenza vaccine, which is currently recommended only for children with certain risk factors.
Preservatives may be used at various stages in the production of vaccines, and sophisticated methods of measurement might detect traces of them in the finished product.
Accusations of harm from vaccinations
Allegations of vaccine injuries in recent decades have appeared in litigation in the United States. Some families have won substantial awards from sympathetic juries, even though most public health officials have said that the claims of injuries were unfounded. In response, several vaccine makers stopped production, which the United States government believed could be a threat to public health, so laws were passed to shield makers from liabilities stemming from vaccine injury claims.
One of the most noteworthy allegations of vaccine-induced injury is the MMR vaccine controversy. A fraudulent 1998 paper by Andrew Wakefield, originally published in The Lancet, presented supposed evidence that the MMR Vaccine (an immunization against measles, mumps and rubella that is typically first administered to children before their first birthday) was linked to the onset of autism spectrum disorders. The article was partially retracted in 2004 by Wakefield's co-authors, and was fully retracted by The Lancet in 2010.
Following the initial claims in 1998, multiple large epidemiological studies were undertaken. Reviews of Wakefield's evidence by the Centers for Disease Control and Prevention, the American Academy of Pediatrics, the Institute of Medicine of the United States National Academy of Sciences, the United Kingdom National Health Service, and the Cochrane Library all found no link between the vaccine and autism. While the Cochrane review expressed a need for improved design and reporting of safety outcomes in MMR vaccine studies, it concluded that the evidence of the safety and effectiveness of MMR in the prevention of diseases that still carry a heavy burden of disease and mortality justifies its global use, and that the lack of confidence in the vaccine has damaged public health. A special court convened in the United States to review claims under the National Vaccine Injury Compensation Program rejected compensation claims from parents of autistic children.
The claims in Wakefield's 1998 The Lancet article were widely reported; vaccination rates in the United Kingdom and Ireland dropped sharply, which was followed by a significantly increased incidence of measles and mumps, resulting in deaths and severe and permanent injuries. Physicians, medical journals, and editors have described Wakefield's actions as fraudulent and tied them to epidemics and deaths, and a 2011 journal article described the vaccine-autism connection as 'the most damaging medical hoax of the last 100 years'.