Vaccination (redirected from vaccinated)

vaccination, means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of live, killed, or altered antigens that stimulate the body to produce antibodies against more dangerous forms. Vaccination was used in ancient times in China, India, and Persia, and was introduced in the West in 1796 by Edward Jenner. Jenner demonstrated that rubbing or scraping the cowpox virus (the term vaccine comes from the Latin vacca, cow) into the skin produced only a local lesion but was sufficient to stimulate the production of antibodies that would defend the body against the more virulent smallpox.

Vaccination has eradicated smallpox worldwide and prevents such diseases as cholera, rabies, and typhoid fever. Vaccines work with the immune system's ability to recognize and destroy foreign proteins (antigens) that it determines are "nonself." Scientists are using this same principle to help the body recognize antigens peculiar to cancer cells. It is also applied in an experimental birth control vaccine that tricks the immune system into believing that human chorionic gonadotropin (HCG), a hormone secreted by a developing fertilized egg, is foreign, thus inactivating it and inducing menstruation even if fertilization has occurred. Vaccines are also used to control animal pests by conferring temporary infertility.

Vaccination programs have been notably successful in the United States. For example, in 1998 the Centers for Disease Control and Prevention reported only one case of poliomyelitis, one of diphtheria, 34 of tetanus, and 89 of measles. Despite the availability of vaccines, many thousands of people in the United States still die each year from vaccine-preventable diseases such as hepatitis and influenza.

Immunization against 17 diseases is recommended for young children and adolescents: hepatitis B (HepB); rotavirus; diphtheria, tetanus (lockjaw), and pertussis (whooping cough), given together as DTaP (formerly DTP) and, for older children, Tdap; Haemophilus influenzae b (Hib); poliomyelitis (IPV); pneumococcal infections, including pneumonia, meningitis, and bacteremia (PCV and PPV); measles, mumps, and rubella, given together as MMR; chicken pox (Var); hepatitis A (HepA); influenza; Neisseria meningitidis (meningococcal meningitis; MCV4, MPSV4); and, for girls only, human papillomavirus (HPV). Researchers are working to develop combination vaccines that would simplify vaccine administration. Immunization against diseases such as yellow fever may be necessary before traveling to some countries. In 2002 the U.S. government decided to reinstitute smallpox vaccination for many military, health-care, and emergency personnel because of concern about a possible bioterror attack using smallpox.

See also inoculation.

Bibliography

See study by A. Allen (2007).

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vaccination [‚vak·sə′nā·shən]

(immunology)

Inoculation of viral or bacterial organisms or antigens to produce immunity in the recipient.

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Vaccination

Active immunization against a variety of microorganisms or their components, with the ultimate goal of protecting the host against subsequent challenge by the naturally occurring infectious agent. The terms vaccine and vaccination were originally used only in connection with Edward Jenner's method for preventing smallpox, introduced in 1796. In 1881 Louis Pasteur proposed that these terms should be used to describe any prophylactic immunization. Vaccination now refers to active immunization against a variety of bacteria, viruses, and parasites (for example, malaria and trypanosomes). See Smallpox

Implicit within Jenner's method of vaccinating against smallpox was the recognition of immunologic cross-reactivity together with the notion that protection can be obtained through active immunization with a different, but related, live virus. It was not until the 1880s that the next immunizing agents, vaccines against rabies and anthrax, were introduced by Pasteur. Two facts of his experiments on rabies vaccines are particularly noteworthy.

First, Pasteur found that serial passage of the rabies agent in rabbits resulted in a weakening of its virulence in dogs. During multiple passages in an animal or in tissue culture cells, mutations accumulate as the virus adapts to its new environment. These mutations adversely affect virus reproduction in the natural host, resulting in lessened virulence. Only as the molecular basis for virulence has begun to be elucidated by modern biologists has it become possible to deliberately remove the genes promoting virulence so as to produce attenuated viruses.

Second, Pasteur demonstrated that rabies virus retained immunogenicity even after its infectivity was inactivated by formalin and other chemicals, thereby providing the paradigm for one class of noninfectious virus vaccine, the “killed”-virus vaccine.

Attenuated-live and inactivated vaccines are the two broad classifications for vaccines. Anti-idiotype antibody vaccines and deoxyribonucleic acid (DNA) vaccines represent innovations in inactivated vaccines. Recombinant-hybrid viruses are novel members of the live-virus vaccine class recently produced by genetic engineering.

Because attenuated-live-virus vaccines reproduce in the recipient, they provoke both a broader and more intense range of antibodies and T-lymphocyte-associated immune responses than noninfectious vaccines. Live-virus vaccines have been administered subdermally (vaccinia), subcutaneously (measles), intramuscularly (pseudorabies virus), intranasally (infectious bovine rhinotracheitis), orally (trivalent Sabin poliovirus), or by oropharyngeal aerosols (influenza). Combinations of vaccines have also been used. Live-virus vaccines administered through a natural route of infection often induce local immunity, which is a decided advantage. However, in the past, attenuated-live virus vaccines have been associated with several problems, such as reversion to virulence, natural spread to contacts, contaminating viruses, lability, and viral interference. See Animal virus, Virulence, Virus classification, Virus interference

Noninfectious vaccines include inactivated killed vaccines, subunit vaccines, synthetic peptide and biosynthetic polypeptide vaccines, oral transgenic plant vaccines, anti-idiotype antibody vaccines, DNA vaccines, and polysaccharide-protein conjugate vaccines. With most noninfectious vaccines a suitable formulation is essential to provide the optimal antigen delivery for maximal stimulation of protective immune responses. Development of new adjuvant (a substance that enhances the potency of the antigen) and vector systems is pivotal to produce practical molecular vaccines. See Antibody, Antigen, Immunity

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Vaccination 

a method of preventing smallpox by artificially infecting a person with vaccinia virus; it is a form of active immunization.

The method of variolation was used in ancient China, India, and Africa. A healthy person was injected subcutaneously or in his nasal mucosa with the contents of smallpox vesicles and pustules, or with dried smallpox pus. This gave him the disease, usually in a mild form, after which he acquired immunity. In the 18th century, variolation was also used in European countries, including Russia. However, it sometimes caused a severe form of the disease. Moreover, a person with the mild form could become a source of infection for those around him. Finally, variolation can also cause other infectious diseases. In 1796 the English physician E. Jenner proposed immunization with the contents of cowpox vesicles; he had observed that milkmaids infected by sick cows suffered a mild, local form of smallpox, with rashes only on the arms, and did not contract the disease subsequently. Jenner’s method was called vaccination.

Modern vaccine is prepared by infecting calves with vaccinia virus (smallpox virus repeatedly passaged in calves and having as a result all the properties of cowpox virus). The contents of an infected calfs pockmarks are ground and mixed with glycerin, which kills foreign microorganisms without destroying the vaccinia virus. Special regulations set forth the main requirements for the production, control, and storage of smallpox vaccine.

The introduction of vaccination in public health practice sharply lowered the incidence of smallpox. However, vaccination is not compulsory in many countries. According to regulations now in effect in the USSR, all children are vaccinated at the age of one or two years or earlier if there is the threat of an epidemic. Vaccination is repeated at the ages of eight and 16; medical personnel, communal service personnel, and some other groups are revaccinated every five years thereafter. Travelers to countries where smallpox exists or persons who have come in contact with those suffering from the disease must also be vaccinated. Vaccination is performed epicutaneously: the skin is disinfected, vaccine applied, and the skin scarified. Bathing is forbidden until the crust falls off. If the skin remains smooth and a scar does not form, the vaccination is considered unsuccessful and is repeated. A vaccination sometimes has severe side effects such as fever, pronounced local reddening, and edema, which soon pass spontaneously. Antivariolic gamma globulin is used if there are complications, which rarely occur.

V. L. VASILEVSKII