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Vaccine |
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A vaccine is an antigenic preparation used to establish immunity to a disease. The term derives from Edward Jenner's use of cowpox ("vacca" means cow in Latin), which, when administered to humans, provided them protection against smallpox, the work which Louis Pasteur and others carried on. Vaccines are based on the concept of variolation originating in China, in which a person is deliberately infected with a weak form of smallpox. Jenner realized that milkmaids who had contact with cowpox did not get smallpox. The process of distributing and administrating vaccines is referred to as vaccination. Since vaccination was much safer, smallpox inoculation fell into disuse and was eventually banned in England in 1840.
Vaccines can be prophylactic (e.g. to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine). Types of vaccines) Avian Flu vaccine development by reverse genetics techniques. There are four types of traditional vaccines[1]:
A number of innovative vaccines are also in development and in use:
Developing immunityThe immune system recognizes vaccine agents as foreign, destroys them, and 'remembers' them. When the virulent version of an agent comes along, the immune system is thus prepared to respond, by (1) neutralizing the target agent before it can enter cells, and (2) by recognizing and destroying infected cells before that agent can multiply to vast numbers.Vaccines have contributed to the eradication of smallpox, one of the most contagious and deadly diseases known to man. Other diseases such as rubella, polio, measles, mumps, chickenpox, and typhoid are nowhere near as common as they were just a hundred years ago. As long as the vast majority of people are vaccinated, it is much more difficult for an outbreak of disease to occur, let alone spread. This effect is called herd immunity. Polio, which is transmitted only between humans, is targeted by an extensive eradication campaign that has seen endemic polio restricted to only parts of four countries.[3] The difficulty of reaching all children, however, has caused the eradication date to be missed twice by 2006. Vaccination schedule
In order to provide best protection, children are recommended to receive vaccinations as soon as their immune systems are sufficiently developed to respond to particular vaccines, with additional 'booster' shots often required to achieve 'full immunity'. This has led to the development of complex vaccination schedules. In the United States, the Advisory Committee on Immunization Practices, which recommends schedule additions for the Center for Disease Control, recommends routine vaccination of children against: hepatitis A, hepatitis B, polio, mumps, measles, rubella, diphtheria, pertussis, tetanus, HiB, chicken pox, rotavirus, influenza, meningococcal disease and pneumonia. The large number of vaccines and boosters recommended (up to 24 injections by age two) has led to problems with achieving full compliance. In order to combat declining compliance rates, various notification systems have been instituted and a number of combination injections are now marketed (e.g., Prevnar and ProQuad vaccines), which provide protection against multiple diseases. Besides recommendations for infant vaccination boosters, many specific vaccines are recommended for repeated injections throughout life -- most commonly for measles, tetanus, influenza, and pneumonia. Pregnant women are often screened for continued resistance to rubella. In 2006, a vaccine was introduced against shingles, a disease caused by the chicken pox virus, which usually affects the elderly. Vaccine recommendations for the elderly concentrate on pneumonia and influenza, which are more deadly to that group. Vaccine controversiesOpposition to vaccination, from a wide array of vaccine critics, has existed since the earliest vaccination campaigns: [4]. A number of vaccines, including those given to very young children, have contained thiomersal, a preservative that metabolizes into ethylmercury. It has been used in some influenza, DTP (diphtheria, tetanus and pertussis) vaccine formulations. Since 1997, use of thimerosal has been gradually diminishing in western industrialized countries after recommendations by medical authorities, but trace amounts of thimerosal remain in many vaccines and in some vaccines, thimerosal has not yet been phased out despite recommendations. Some states in the USA have enacted laws banning the use of thimerosal in childhood vaccines. In the late 1990s, controversy over vaccines escalated in both the US and the United Kingdom when a study, published in the respected journal Lancet, by Dr. Andrew Wakefield suggested a possible link between bowel disorders, autism and the MMR vaccine, and urged further research.[1] His report garnered significant media attention, leading to a drop in the uptake of the MMR vaccine in the United Kingdom and some other countries. In response to the controversies, a number of studies with larger sample sizes were conducted, and failed to confirm the findings.[5] [6]. In 2004, 10 of the 13 authors of the original Wakefield study retracted the paper's "interpretation", or conclusion, section, which had claimed: "Interpretation. We identified associated gastrointestinal disease and developmental regression in a group of previously normal children, which was generally associated in time with possible environmental triggers." The retraction of this claim stated that the data were insufficient to establish a causal link between MMR vaccine and autism.[7] Wakefield was later found to have received £435,000 in fees from trial lawyers attempting to show the vaccine was dangerous [8] [9]. Also in 2004, the United States' Institute of Medicine reported that evidence "favors rejection" of any link between vaccines containing thimerosal, or MMR, and the development of autism [10]. In 2004 and 2005, England and Wales experienced an increase in the incidence of mumps infections among adolescents and young adults. The age group affected were too old to have received the routine MMR immunisations around the time the paper by Wakefield et al was published, and too young to have contracted natural mumps as a child, and thus to achieve a herd immunity effect. With the decline in mumps that followed the introduction of the MMR vaccine, these individuals had not been exposed to the disease, but still had no immunity, either natural or vaccine induced. Therefore, as immunization rates declined following the controversy and the disease re-emerged, they were susceptible to infection. [11] [12]. This and similar examples indicate the importance of:
There is opposition to any type of vaccination from some sectors of the community, particularly those who favor 'alternative' health care. Some skeptics claim that mass immunization is a eugenics program. Naturopaths and other alternative health care practitioners sometimes offer their own, alternative treatments to conventional vaccination. In Australia, a massive increase in vaccination rates was observed when the federal government made certain benefits (such as the universal 'Family Allowance' welfare payments for parents of children) dependent on vaccination. As well, children were not allowed into school unless they were either vaccinated or their parents completed a statutory declaration refusing to immunize them, after discussion with a doctor, and other bureaucracy. (Similar school-entry vaccination regulations have been in place in some parts of Canada for several years.) It became easier and cheaper to vaccinate one's children than not to. When faced with the annoyance, many more casual objectors simply gave in. Another vaccination controversy concerns smallpox. Since it has been eradicated, some suggest that the stores of smallpox virus should be destroyed. In an article on Newswise [13] both sides debate the issue: "The destruction of remaining smallpox virus stocks is an overdue step forward for public health and security that will dramatically reduce the possibility that this scourge will kill again, either by accident or design, argues Edward Hammond of The Sunshine Project, an organisation seeking international consensus against biological weapons." "But John Agwunobi of the US Department of Health and Human Services believes that clandestine stocks almost certainly exist and that destroying the virus would be “irreversible and short sighted.” [14] Efficacy of vaccinesVaccines do not guarantee complete protection from a disease. Sometimes this is because the host's immune system simply doesn't respond adequately or at all. This may be due to a lowered immunity in general (diabetes, steroid use, HIV infection) or because the host's immune system does not have a B-cell capable of generating antibodies to that antigen.Even if the host develops antibodies, the human immune system is not perfect and in any case the immune system might still not be able to defeat the infection. Adjuvants are typically used to boost immune response. Adjuvants are sometimes called the dirty little secret of vaccines [15] in the scientific community, as not much is known about how adjuvants work. Most often aluminium adjuvants are used, but adjuvants like squalene are also used in some vaccines and more vaccines with squalene and phosphate adjuvants are being tested. The efficacy or performance of the vaccine is dependent on a number of factors:
Economics of vaccine developmentOne challenge in vaccine development is economic: many of the diseases most demanding a vaccine, including HIV, malaria and tuberculosis, exist principally in poor countries. Although some contend pharmaceutical firms and biotech companies have little incentive to develop vaccines for these diseases, because there is little revenue potential, the number of vaccines actually administered has risen dramatically in recent decades. This increase, particularly in the number of different vaccines administered to children before entry into schools may be due to government mandates, rather than economic incentive. Most vaccine development to date has relied on 'push' funding by government and non-profit organizations, of government agencies, universities and non-profit organizations.Many researchers and policymakers are calling for a different approach, using 'pull' mechanisms to motivate industry. Mechanisms such as prizes, tax credits, or advance market commitments could ensure a financial return to firms that successfully developed a HIV vaccine. If the policy were well-designed, it might also ensure people have access to a vaccine if and when it is developed. Statistics from the government agencies of the U.S., the British Commonwealth and the U.K. show that between the 1800s and the time various vaccines were introduced, the incidences of the diseases for which vaccines were provided were reduced by 70%-90%. For some, this prompts the question as to whether the reduction in the morbidity and mortality due to these diseases is owed to improved sewage systems, food refrigeration, improved home and work environments, and the introduction of antibiotics, all of which occurred during the same period. PreservativesIn order to extend shelf life and reduce production and storage costs, thimerosal, a preservative containing about 49% of a form of mercury called ethylmercury, was used routinely until recent years.[16] Thimerosal has been phased out in the U.S. in all but a few flu vaccines [17] (it has been phased out earlier in other countries, e.g. Denmark in 1992), but may be used in stages of manufacture. Parents wishing to avoid this preservative, most common in multi-dose containers of influenza vaccine, may specifically ask for thimerosal-free alternatives that contain only trace amounts.[18]A study published in the September 2007 New England Journal of Medicine reported no causal association between early exposure to mercury from thimerosal-containing vaccines and neurological problems by the age of 7 to 10 years old.[2] Vaccines for nonhumans
See also
References1. ^ Wakefield A, Murch S, Anthony A et al. (1998). "Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children". Lancet 351 (9103): 637–41. DOI:10.1016/S0140-6736(97)11096-0. PMID 9500320. Retrieved on 2007-09-05.
2. ^ William W. Thompson, Ph.D., et al. (2007). "Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 years". New England Journal of Medicine 357 (13): 1281-1292.
External linksGeneral
Vaccine proponent views
Vaccine safety critical views
An antigen or immunogen is a molecule that stimulates an immune response. The word originated from the notion that they can stimulate antibody generation. We now know that the immune system does not only consist of antibodies. ..... Click the link for more information. Immunity is a medical term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. ..... Click the link for more information. Edward Jenner, FRS, (17 May, 1749 – 26 January, 1823) was an English country doctor who studied nature and his natural surroundings from childhood and practiced medicine in Berkeley, Gloucestershire, England. ..... Click the link for more information. Cowpox Classification & external resources ICD-10 B08.0 ICD-9 051.0 MeSH D015605 Cowpox virus Virus classification Group: Group I (dsDNA) Family: Poxviridae ..... Click the link for more information. Latin}}} Official status Official language of: Vatican City Used for official purposes, but not spoken in everyday speech Regulated by: Opus Fundatum Latinitas Roman Catholic Church Language codes ISO 639-1: la ISO 639-2: lat ..... Click the link for more information. Smallpox Classification & external resources A child infected with smallpox ICD-10 B 03. ICD-9 050 DiseasesDB 12219 MedlinePlus 001356 eMedicine emerg/885 MeSH D012899 Main characteristics ..... Click the link for more information. Louis Pasteur (December 27 1822 – September 28 1895) was a French chemist best known for his remarkable breakthroughs in microbiology. His experiments confirmed the germ theory of disease, also reducing mortality from puerperal fever (childbed), and he created the first ..... Click the link for more information. The word "Inoculation" refers to the placement of something to where it will grow or reproduce, and is most commonly used in respect of the introduction of a serum, vaccine, or antigenic substance into the body of a human or animal, especially to produce or boost immunity to a ..... Click the link for more information. Vaccination is the administration of antigenic material to produce immunity to a disease. This will prevent or ameliorate the effects of infection by a pathogen. The material administrated can either be live, but weakened forms of pathogens such as bacteria or viruses, ..... Click the link for more information. Prophylaxis (Greek "προφύλαξις" to guard or prevent beforehand) is any medical or public health procedure whose purpose is to prevent, rather than treat or cure, disease. ..... Click the link for more information. An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply (usually at the expense of the host). ..... Click the link for more information. A pathogen or infectious agent is a biological agent that causes disease or illness to its host.[1] The term is most often used for agents that disrupt the normal physiology of a multicellular animal or plant. ..... Click the link for more information. Pharmacotherapy is the practice of treating diseases with medication. See also
External links
..... Click the link for more information. The term cancer vaccine is often used to describe a process whereby a person's immune system is coaxed into recognizing and destroying malignant cells without harming normal cells. ..... Click the link for more information. Flu
The flu vaccine is a vaccine to protect against the highly variable influenza virus. ..... Click the link for more information. Cholera Classification & external resources Vibrio cholerae: The bacterium that causes cholera (SEM image) ICD-10 A 00. ICD-9 001 DiseasesDB 2546 MedlinePlus 000303 eMedicine med/351 ped/382 MeSH C01.252.400. ..... Click the link for more information. Bubonic Plague Classification & external resources Yersinia pestis'' seen at 2000x magnification with a fluorescent label. This bacterium, carried and spread by fleas, is the cause of the various forms of the disease plague. ICD-10 A 20. ..... Click the link for more information. Hepatitis A Classification & external resources ICD-10 B 15. - ICD-9 070.1 DiseasesDB 5757 MedlinePlus 000278 eMedicine med/991 ped/977 MeSH D006506 Hepatitis A virus ..... Click the link for more information. Attenuation in virology is reducing the virulence of a virus, whilst keeping it viable (or 'live'), for the purpose of creating a vaccine. It is the counterpart of the vaccines produced by 'killing' the virus (inactivated vaccine) ..... Click the link for more information. yellow fever Classification & external resources ICD-10 A 95. ICD-9 060 eMedicine med/2432 emerg/645 Yellow fever virus TEM micrograph: Multiple yellow fever virions (234,000x magnification). ..... Click the link for more information. Measles Classification & external resources How Measles affects the skin. ICD-10 B 05. .- ICD-9 055 DiseasesDB 7890 MedlinePlus 001569 eMedicine derm/259 emerg/389 Measles virus ..... Click the link for more information. Rubella Classification & external resources ICD-10 B 06. ICD-9 056 DiseasesDB 11719 MedlinePlus 001574 eMedicine emerg/388 peds/2025 derm/259 Rubella virus ..... Click the link for more information. Mumps virus For other uses of the word MUMPS, see . Mumps or epidemic parotitis is a viral disease of humans. ..... Click the link for more information. A toxoid is a bacterial toxin whose toxicity has been weakened or suppressed either by chemical (formalin) or heat treatment, while other properties, typically immunogenicity, are maintained. ..... Click the link for more information. Tetanus Classification & external resources Muscular spasms in a patient suffering from tetanus. Painting by Sir Charles Bell, 1809. ICD-10 A 33. -A 35. ICD-9 037 , 771. ..... Click the link for more information. MeSH D004165 Diphtheria (Greek διφθερα (diphthera) — “pair of leather scrolls”), is an upper respiratory tract illness characterized by sore throat, low-grade fever, and an adherent membrane (a ..... Click the link for more information. In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles (or "coassembles") with other protein molecules to form a multimeric or oligomeric protein. ..... Click the link for more information. Ascomycota (sac fungi)
..... Click the link for more information. Virus like particles (VLPs) consist of viral protein(s) derived from the structural proteins of a virus. In some cases these proteins are embedded within a lipid bilayer. These particles resemble the virus from which they were derived but lack viral nucleic acid, meaning that they ..... Click the link for more information. Papillomaviruses were first identified in the early 20th century, when it was shown that skin warts, or papillomas, could be transmitted between individuals by a filterable infectious agent. ..... Click the link for more information. This article is copied from an article on Wikipedia® - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the Wikipedia® encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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Most scientists believe that an effective preventive AIDS vaccine is challenging but feasible. Each vaccine prompts the immune system to produce antibodies against the hemagglutinin and, therefore, against the virus. has entered into a supply contract with the UK government for pre-pandemic influenza vaccine for a stockpile based on the H5N1 avian influenza virus strain. |
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Vaccine
