The induction of immunity against infectious agents. The name is derived from vaccinia or cowpox - the virus that was administered by Edward Jenner in 1792 to protect against smallpox. This was the first time the technique had been used in the West, though the Chinese had discovered the importance of inoculation against smallpox in the 16th-c, and in 1773 the Qing emperor had all his troops inoculated. It involves the introduction into the body of a small quantity of living or dead micro-organisms, or proteins (antigens) derived from them. This sensitizes the body to recognize the micro-organism as foreign and to mount an effective immune response against it in the event of a future infection, thereby preventing the development of the disease. Vaccines have been used successfully to protect against a variety of infectious diseases, including tuberculosis, poliomyelitis, tetanus, diphtheria, measles, mumps, and rubella. Smallpox has now been eradicated by a worldwide vaccination programme. In 1998 controversy arose in the UK when British surgeon Andrew Wakefield (1957 ) suggested a link between the MMR (measlesmumpsrubella) vaccine and autism, but other studies have so far not confirmed the link, and the three-in-one procedure continues to be widely used worldwide.
Vaccination is the process of administering weakened or dead pathogens to a healthy person or animal, with the intent of conferring immunity against a targeted form of a related disease agent.
The term was coined by Edward Jenner and adapted by Louis Pasteur for his pioneering work in vaccination. Vaccination (Latin: vacca—cow) is so named because the first vaccine was derived from a virus affecting cows: the cowpox virus, a relatively benign virus that provides a degree of immunity to smallpox, a contagious and deadly disease.
Vaccination efforts have been met with some resistance since its inception. Early success and compulsion brought widespread acceptance and mass vaccination campaigns were undertaken which have greatly reduced the incidence of many diseases in many areas. The eradication of smallpox, which was last seen in a natural case in 1977, is considered the most spectacular success of vaccination. Currently some people assert that childhood vaccination causes some autoimmune disease and autism. Scientific studies have not demonstrated a link, however, the assertion found space in a United States House of Representatives report in 2003 which included the suggestion that mercury derivatives in vaccines might have been a cause of autism.[]
Triggering immune sensitization
In the generic sense, the process of artificial induction of immunity, in an effort to protect against infectious disease, works by 'priming' the immune system with an 'immunogen'.
Some modern vaccines are administered after the patient already has contracted a disease, as in the cases of experimental AIDS, cancer and Alzheimer's disease vaccines. Vaccinia given after exposure to smallpox, within the first four days, is reported to attenuate the disease considerably, and vaccination within the first week is known to be beneficial to a degree.
Most vaccines are given by hypodermic injection as they are not absorbed reliably through the gut. Live attenuated Polio, some Typhoid and Cholera Vaccines are given orally in order to produce immunity based in the bowel.
History of vaccinations
Vaccination campaigns have spread throughout the globe since Jenner's smallpox vaccine of 1796, sometimes prescribed by law or regulations (See Vaccination Acts). Vaccines are now used to fight a wide variety of disease threats besides smallpox.
Prior to vaccination with cowpox, the only known protection against smallpox was inoculation or variolation (Variola - the Smallpox viruses) where a small amount of live smallpox virus was administered to the patient;
Consistency would suggest the activity should have predated Jenner's description of an effective vaccination system, and there is some history relating to opposition to the older and more hazardous procedure of variolation.
In 2000, the Global Alliance for Vaccines and Immunization was established to strengthen routine vaccinations and introduce new and under-used vaccines in countries with a per capita GDP of under US$1000.
Compulsory vaccination and opposition to vaccination
In an attempt to eliminate the risk of outbreaks of some diseases, several governments and other institutions have instituted policies requiring vaccination for all people. Compulsory vaccination is believed to have greatly reduced the rates of some infectious diseases.
Beginning with early vaccination in the nineteenth century, these policies led to resistance from a variety of groups, collectively called anti-vaccinationists, who objected on ethical, political, medical safety, religious, and other grounds. Many modern vaccination policies allow exemptions for people who have compromised immune systems, allergies to the components used in vaccinations or strongly-held objections.
In 1904 in the city of Rio de Janeiro, Brazil a government program of mandatory smallpox vaccination resulted in the so-called Vaccine Revolt, several days of rioting with considerable property damage and a number of deaths.
Herd immunity and medical risk management issues
Vaccination campaigns are generally accepted as having contributed to the worldwide elimination of smallpox, through herd immunity, and to the restriction of polio to isolated pockets in countries where healthcare access is difficult. The risk management practices of government health agencies' promoting widespread vaccination campaigns has prompted increasing controversy in recent years, despite the fact that many once-common childhood diseases, such as mumps, measles and rubella, are now relatively rare in developed countries.
Nevertheless, vaccination campaigns may have unfortunate co-evolutionary side-effects, particularly if they produce a selective pressure in favor of certain strains against which there are no vaccines or treatment. Another problem related to co-evolution is that vaccines that may eliminate one infectious diseases or another may, in turn, allow others to thrive in the ecological niche that has been vacated.
An incompletely-successful attempt at eradication of a disease through vaccination might increase the average age of contraction of the disease. In diseases such as measles, where there is a higher rate of complication in older people, the overall effect might, in theory, be to cause more deaths than before the vaccination was introduced.
Adjuvants and preservatives
Vaccines typically contain one or more adjuvants, used to boost the immune response.
In the preparation for the 1990 Gulf campaign, Pertussis vaccine (not acellular) was used as an adjuvant for Anthrax vaccine.
Vaccine research
Some major contemporary research in vaccination focuses on development of vaccinations for diseases including HIV and malaria.
Vaccine is an international peer-reviewed journal for vaccination researchers, indexed in Medline pISSN: 0264-410X.
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