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Child receiving an oral polio vaccine.

Vaccination is the administration of antigenic material (the vaccine) to produce immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens. There is strong evidence for the influenza vaccine[1], the HPV vaccine[2] and the chicken pox vaccine[3] among others. Vaccination is generally considered to be the most effective and cost-effective method of preventing infectious diseases. The material administered can either be live but weakened forms of pathogens (bacteria or viruses), killed or inactivated forms of these pathogens, or purified material such as proteins. Smallpox was the first disease people tried to prevent by purposely inoculating themselves with other types of infections; smallpox inoculation was started in China or India before 200 BC.[4] In 1718, Lady Mary Wortley Montagu reported that the Turks had a habit of deliberately inoculating themselves with fluid taken from mild cases of smallpox, and that she had inoculated her own children.[5] Before 1796 when British physician Edward Jenner tested the possibility of using the cowpox vaccine as an immunisation for smallpox in humans for the first time, at least six people had done the same several years earlier: a person whose identity is unknown, England, (about 1771); a Mrs. Sevel, Germany (about 1772); a Mr. Jensen, Germany (about 1770); Benjamin Jesty, England, in 1774; a Mrs. Rendall, England (about 1782); and Peter Plett, Germany, in 1791.[6]

The word vaccination was first used by Edward Jenner in 1796. Louis Pasteur furthered the concept through his pioneering work in microbiology. Vaccination (Latin: vacca—cow) is so named because the first vaccine was derived from a virus affecting cows—the relatively benign cowpox virus—which provides a degree of immunity to smallpox, a contagious and deadly disease. In common speech, 'vaccination' and 'immunization' generally have the same colloquial meaning. This distinguishes it from inoculation which uses unweakened live pathogens, although in common usage either is used to refer to an immunization. The word "vaccination" was originally used specifically to describe the injection of smallpox vaccine.[4][6]

Vaccination efforts have been met with some controversy since their inception, on ethical, political, medical safety, religious, and other grounds. In rare cases, vaccinations can injure people and they may receive compensation for those injuries. Early success and compulsion brought widespread acceptance, and mass vaccination campaigns were undertaken which are credited with greatly reducing the incidence of many diseases in numerous geographic regions.

Contents

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'. Stimulating immune response, via use of an infectious agent, is known as immunization. Vaccinations involve the administration of one or more immunogens, which can be administered in several forms.

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. The first rabies immunization was given by Louis Pasteur to a child bitten by a rabid dog, subsequently post-exposure immunization to rabies has generally been followed by survival. The essential empiricism behind such immunizations is that the vaccine triggers an immune response more rapidly than the natural infection itself.

Most vaccines are given by hypodermic injection as they are not absorbed reliably through the intestines. Live attenuated polio, some typhoid and some cholera vaccines are given orally in order to produce immunity based in the bowel.

Types of vaccinations

All vaccinations work by presenting a foreign antigen to the immune system in order to evoke an immune response, but there are several ways to do this. The four main types that are currently in clinical use are as follows:

  1. An inactivated vaccine consists of virus particles which are grown in culture and then killed using a method such as heat or formaldehyde. The virus particles are destroyed and cannot replicate, but the virus capsid proteins are intact enough to be recognized and remembered by the immune system and evoke a response. When manufactured correctly, the vaccine is not infectious, but improper inactivation can result in intact and infectious particles. Since the properly produced vaccine does not reproduce, booster shots are required periodically to reinforce the immune response.
  2. In an attenuated vaccine, live virus particles with very low virulence are administered. They will reproduce, but very slowly. Since they do reproduce and continue to present antigen beyond the initial vaccination, boosters are required less often. These vaccines are produced by passaging virus in cell cultures, in animals, or at suboptimal temperatures, allowing selection of less virulent strains, or by mutagenesis or targeted deletions in genes required for virulence. There is a small risk of reversion to virulence, this risk is smaller in vaccines with deletions. Attenuated vaccines also cannot be used by immunocompromised individuals.
  3. Virus-like particle vaccines consist of viral protein(s) derived from the structural proteins of a virus. These proteins can self-assemble into particles that resemble the virus from which they were derived but lack viral nucleic acid, meaning that they are not infectious. Because of their highly repetitive, multivalent structure, virus-like particles are typically more immunogenic than subunit vaccines (described below). The human papillomavirus and Hepatitis B virus vaccines are two virus-like particle-based vaccines currently in clinical use.
  4. A subunit vaccine presents an antigen to the immune system without introducing viral particles, whole or otherwise. One method of production involves isolation of a specific protein from a virus or bacteria (such as a bacterial toxin) and administering this by itself. A weakness of this technique is that isolated proteins may have a different three-dimensional structure than the protein in its normal context, and will induce antibodies that may not recognize the infectious organism. In addition, subunit vaccines often elicit weaker antibody responses than the other classes of vaccines.

A number of other vaccine strategies are under experimental investigation. These include DNA vaccination and recombinant viral vectors.

History

Jenner's handwritten draft of the first vaccination.

Early forms of vaccination were developed in ancient China as early as 200 B.C.[4] Scholar Ole Lund comments: "The earliest documented examples of vaccination are from India and China in the 17th century, where vaccination with powdered scabs from people infected with smallpox was used to protect against the disease. Smallpox used to be a common disease throughout the world and 20% to 30% of infected persons died from the disease. Smallpox was responsible for 8% to 20% of all deaths in several European countries in the 18th century. The tradition of vaccination may have originated in India in AD 1000."[7] The mention of vaccination in the Sact'eya Grantham, an Ayurvedic text, was noted by the French scholar Henri Marie Husson in the journal Dictionaire des sciences me`dicales.[8] Almroth Wright, the professor of pathology at Netley, further helped shape the future of vaccination by conducting limited experiments on the professional staff at Netly, including himself. The outcome of these experiments resulted in further development of vaccination in Europe.[9] The Anatolian Ottoman Turks knew about methods of vaccination about a hundred years before Edward Jenner to whom the discovery is attributed. They called vaccination Ashi or engrafting, which they used to apply to their children with cowpox taken from the breast of cattle. This kind of vaccination and other forms of variolation were introduced into England by Lady Montagu, a famous English letter-writer and wife of the English ambassador at Istanbul between 1716 and 1718, who'd almost died from smallpox as a young adult and was physically scarred from it. She came across the Turkish methods of vaccination, consenting to have her son inoculated by the Embassy surgeon Charles Maitland in the Turkish way. Lady Montagu wrote to her sister and friends in England describing the process in details. On her return to England she continued to propagate the Turkish tradition of vaccination and had many of her relatives inoculated. The breakthrough came when a scientific description of the vaccination operation was submitted to the Royal Society in 1724 by Dr Emmanual Timoni, who had been the Montagu’s family physician in Istanbul. Inoculation was adopted both in England and in France nearly half a century before Jenner's famous smallpox vaccine of 1796.[10]

Since then vaccination campaigns have spread throughout the globe, sometimes prescribed by law or regulations (See Vaccination Acts). Vaccines are now used to fight a wide variety of disease threats besides smallpox. Louis Pasteur further developed the technique during the 19th century, extending its use to protecting against bacterial anthrax and viral rabies. The method Pasteur used entailed treating the infectious agents for those diseases so they lost the ability to cause serious disease. Pasteur adopted the name vaccine as a generic term in honor of Jenner's discovery, which Pasteur's work built upon.

A doctor performing a typhoid vaccination, 1943.

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; this carried the serious risk that the patient would be killed or seriously ill. The death rate from variolation was reported to be around a tenth of that from natural infection with Variola, and the immunity provided was considered quite reliable. Factors contributing to the efficacy of variolation probably include the choices of Variola Minor strains used, the relatively low number of cells infected in the first phase of multiplication following initial exposure, and the exposure route used, via the skin or nasal lining rather than inhalation of droplets into the lungs.

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[citation needed].

In modern times, the first vaccine-preventable disease targeted for eradication was smallpox. The World Health Organization (WHO) coordinated the global effort to eradicate this disease. The last naturally occurring case of smallpox occurred in Somalia in 1977.

In 1988, the governing body of WHO targeted polio for eradication by the year 2000. Although the target was missed, eradication is very close. The next eradication target would most likely be measles, which has declined since the introduction of measles vaccination in 1963.

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. GAVI is now entering its second phase of funding, which extends through 2014.

Policies and enforcement

Poster for vaccination against smallpox.

In an attempt to eliminate the risk of outbreaks of some diseases, at various times several governments and other institutions have instituted policies requiring vaccination for all people. For example, an 1853 law required universal vaccination against smallpox in England and Wales, with fines levied on people who did not comply. Common contemporary U.S. vaccination policies require that children receive common vaccinations before entering school. Most other countries also have some compulsory vaccinations.

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. Common objections are that compulsory vaccination represents excessive government intervention in personal matters, or that the proposed vaccinations are not sufficiently safe.[11] Many modern vaccination policies allow exemptions for people who have compromised immune systems, allergies to the components used in vaccinations or strongly-held objections.[12]

Allegations of vaccine injuries in recent decades have appeared in litigation in the U.S. Some families have won substantial awards from sympathetic juries, even though most public health officials believed that the claims of injuries were unfounded.[13] In response, several vaccine makers stopped production, threatening public health, and laws were passed to shield makers from liabilities stemming from vaccine injury claims.[13]

In countries with limited financial resources, limited coverage is a major problem causing unnecessary morbidity and mortality.Mean coverage may often appear fairly adequate. However, when analyzed in detail, effective coverage may be nevertherless be rather be poor.[14]More affluent countries are able to subsidize vaccinations for at-risk groups, resulting in more comprehensive and effective cover. In Australia, for example, the Government subsidizes vaccinations for seniors and indigenous Australians.[15]

Public Health Law Research[16], an independent organization, reported in 2009 that there is insufficient evidence to assess the effectiveness of requiring vaccinations as a condition for specified jobs as a means of reducing incidence of specific diseases among particularly vulnerable populations[17]; that there is sufficient evidence supporting the effectiveness of requiring vaccinations as a condition for attending child care facilities and schools.[18]; and that there is strong evidence supporting the effectiveness of standing orders, which allow healthcare workers without prescription authority to administer vaccine as a public health intervention aimed at increasing vaccination rates.[19]

Adjuvants and preservatives

Vaccines 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 aqueous tetanus toxoid. 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 (not acellular) 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.

They may also contain preservatives, which are used 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 U.S. that contains thiomersal in greater than trace amounts is the influenza vaccine [1], which is currently recommended only for children with certain risk factors.[20] The UK is considering Influenza immunisation in children perhaps as soon as in 2006-7. Single-dose Influenza vaccines supplied in the UK do not list Thiomersal (its UK name) in the ingredients. Preservatives may be used at various stages of production of vaccines, and the most sophisticated methods of measurement might detect traces of them in the finished product, as they may in the environment and population as a whole [2].

Methods of administration

A vaccine administration may be oral, by injection (intramuscular, intradermal, subcutaneous), by puncture, transdermal or intranasal.[21]

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.

See also

References

  1. ^ Fiore AE, Bridges CB, Cox NJ (2009). "Seasonal influenza vaccines". Curr. Top. Microbiol. Immunol. 333: 43–82. doi:10.1007/978-3-540-92165-3_3. PMID 19768400. 
  2. ^ Chang Y, Brewer NT, Rinas AC, Schmitt K, Smith JS (July 2009). "Evaluating the impact of human papillomavirus vaccines". Vaccine 27 (32): 4355–62. doi:10.1016/j.vaccine.2009.03.008. PMID 19515467. 
  3. ^ Liesegang TJ (August 2009). "Varicella zoster virus vaccines: effective, but concerns linger". Can. J. Ophthalmol. 44 (4): 379–84. doi:10.1139/i09-126. PMID 19606157. 
  4. ^ a b c Lombard M, Pastoret PP, Moulin AM (2007). "A brief history of vaccines and vaccination". Rev. - Off. Int. Epizoot. 26 (1): 29–48. PMID 17633292. 
  5. ^ Behbehani AM (1983). "The smallpox story: life and death of an old disease". Microbiol. Rev. 47 (4): 455–509. PMID 6319980. http://mmbr.asm.org/cgi/pmidlookup?view=long&pmid=6319980. 
  6. ^ a b Plett PC (2006). "[Peter Plett and other discoverers of cowpox vaccination before Edward Jenner"] (in German). Sudhoffs Arch 90 (2): 219–32. PMID 17338405. http://lib.bioinfo.pl/meid:4459. Retrieved 2008-03-12. 
  7. ^ Lund, Ole; Nielsen, Morten Strunge and Lundegaard, Claus (2005). Immunological Bioinformatics. MIT Press. ISBN 0262122804
  8. ^ Chaumeton, F.P.; F.V. Me`rat de Vaumartoise. Dictionaire des sciences me`dicales. Paris: C.L.F. Panckoucke, 1812-1822, lvi (1821).
  9. ^ Curtin, Phillip (1998). "Disease and Empire: The Health of European Troops in the Conquest of Africa". Cambridge University Press. ISBN 0521598354
  10. ^ Anthony Henricy (ed.) (1796). Lady Mary Wortley Montagu,Letters of the Right Honourable Lady Mary Wortley Montagu:Written During her Travels in Europe,Asia and Africa. 1. pp. 167–169. 
  11. ^ Wolfe R, Sharp L (2002). "Anti-vaccinationists past and present". BMJ 325 (7361): 430–2. doi:10.1136/bmj.325.7361.430. PMID 12193361. http://bmj.bmjjournals.com/cgi/content/full/325/7361/430. 
  12. ^ Salmon DA, Teret SP, MacIntyre CR, Salisbury D, Burgess MA, Halsey NA (2006). "Compulsory vaccination and conscientious or philosophical exemptions: past, present, and future". Lancet 367 (9508): 436–42. doi:10.1016/S0140-6736(06)68144-0. PMID 16458770. 
  13. ^ a b Sugarman SD (2007). "Cases in vaccine court—legal battles over vaccines and autism". N Engl J Med 357 (13): 1275–7. doi:10.1056/NEJMp078168. PMID 17898095. http://content.nejm.org/cgi/content/full/357/13/1275. 
  14. ^ The fallacy of coverage: uncovering disparities to improve immunization rates through evidence. Results from the Canadian International Immunization Initiative Phase 2 - Operational Research Grants. Sharmila L Mhatre and Anne-Marie Schryer-Roy. BMC International Health and Human Rights 2009, 9(Suppl 1):S1. doi:10.1186/1472-698X-9-S1-S1
  15. ^ "Time to think about vaccinations again", Medicines Talk, Sydney, 3 February 2010.
  16. ^ Public Health Law Research
  17. ^ Laws and Policies Requiring Specified Vaccinations among High Risk Populations
  18. ^ Vaccination Requirements for Child Care, School and College Attendance
  19. ^ Standing Orders for Vaccination
  20. ^ Melinda Wharton. National Vaccine Advisory committee U.S.A. national vaccine plan
  21. ^ Plotkin, Stanley A. (2006). Mass Vaccination: Global Aspects - Progress and Obstacles (Current Topics in Microbiology & Immunology). Springer-Verlag Berlin and Heidelberg GmbH & Co. K. ISBN 978-3540293828. 

External links

  • Vaccine Research Center: Information regarding preventative vaccine research studies
  • The Vaccine Page links to resources in many countries.
  • Immunisation Immunisation schedule for children in the UK. Published by the UK Department of Health.
  • CDC.gov - 'National Immunization Program: leading the way to healthy lives', US Centers for Disease Control (CDC information on vaccinations)
  • CDC.gov - 'Mercury and Vaccines (Thimerosal)', US Centers for Disease Control
  • Immunize.org - Immunization Action Coalition' (nonprofit working to increase immunization rates)
  • WHO.int - 'Immunizations, vaccines and biologicals: Towards a World free of Vaccine Preventable Diseases', World Health Organization (WHO's global vaccination campaign website)
  • Health-EU Portal Vaccinations in the EU


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

Medical warning!
This article is from the 1911 Encyclopaedia Britannica. Medical science has made many leaps forward since it has been written. This is not a site for medical advice, when you need information on a medical condition, consult a professional instead.

VACCINATION (from Lat. vacca, a cow), the term originally devised for a method of protective inoculation against smallpox, consisting in the intentional transference to the human being of the eruptive disease of cattle called cow-pox (vaccinia). The discovery of vaccination is due to Dr Edward Jenner, at the time a country medical practitioner of Berkeley, in the vale of Gloucester, whose investigations were first published in 1798 in the form of a pamphlet entitled An Inquiry into the Causes and Ef f ects of the V ariolae V accinae, &c. Many years previously, while he was an apprentice to a medical man at Sodbury, near Bristol, his attention was directed to a belief, widely prevalent in Gloucestershire during the latter half of the 18th century, that those persons who in the course of their employment on dairy farms happened to contract cow-pox were thereby protected from a subsequent attack of small-pox. In particular, his interest was aroused by a casual remark made by a young countrywoman who happened to come to the surgery one day for advice, and who, on hearing mention made of small-pox, immediately volunteered the statement that she could not take the disease, as she had had cow-pox. On coming up to London in 1770, to finish his medical education, Jenner became a pupil of John Hunter, with whom he frequently discussed the question of the possibility of obtaining protection against small-pox. On his return to his native village of Berkeley in 1773, to practise as a medical man, he took every opportunity of talking over and investigating the matter, but it was not until May 1796 that he actually began to make experiments. His first case of vaccination was that of a boy eight years of age, named James Phipps, whom he inoculated in the arm with cow-pox matter taken from a sore on the hand of Sarah Nelmes, a dairymaid, who had become infected with the disease by milking cows suffering from cowpox. It was apparently not until 1798 that he made his first attempt to carry on a strain of lymph from arm to arm. In the spring of that year he inoculated a child with matter taken directly from the nipple of a cow, and from the resulting vesicle on the arm of the child first operated upon, he inoculated, or, as it may now be more correctly termed, " vaccinated," another. From this child several others were vaccinated. From one of these a fourth remove was successfully carried out, and finally a fifth. Four of these children were subsequently inoculated with small-pox - the " variolous test " - without result., The success of many such experiments, in his own hands and in those of his contemporaries, led Jenner to express his belief - a mistaken one, as events have proved - that the protective influence of vaccination would be found to last throughout the lifetime of the person operated on. Obviously he did not realize the fact that the data at his disposal were insufficient for the formation of an accurate judgment on this point, since time alone could prove the exact duration of the protection originally obtained. Subsequent experience has demonstrated that, as has been well said by a writer in the Edinburgh Review, " even after efficient vaccination a slow progress away from safety and towards danger is inevitable, and re-vaccination at least once after childhood is necessary if protection is to be maintained. " In applying to cow-pox the term " variolae vaccinae," Jenner gave expression to his belief that this disease was in Relation- reality nothing more nor less than small-pox of the ship of cow. But soon it was discovered that if there were small- such a malady as " small-pox of the cow," there pox and was also, as Dr Loy first satisfactorily demonstrated, cow-pox. a small-pox of the horse, which, under the name of " grease," was resorted to from time to time as a source of vaccine lymph. Jenner had, indeed, put forward the suggestion that " grease " was a necessary antecedent to cowpox; but even taking this term to have been used by him in the sense of horse-pox, he was, in all probability, mistaken in his assumption. At the same time, however, there can be little doubt that these two diseases are very closely allied, if indeed they be not identical. As evidence of a definite relationship between human small-pox and cow-pox, it may be mentioned that whereas, prior to the introduction of vaccination, epidemics of these disorders frequently arose concurrently, the so-called " natural " cow-pox has now in great measure disappeared. There is, moreover, no appreciable difference in the minute anatomical appearances characteristic of the eruption following on inoculation of one or other of these two affections in the human subject. But of far greater importance in this connexion are the results obtained by numerous observers who, in various parts of the world, and almost from the time of Jenner onwards, have set themselves the task of attempting, by experimental methods, to solve the problem of the true relationship of variola to vaccinia. As the outcome of this work it may now be definitely stated that small-pox lymph, more especially, as the present writer has shown, if obtained from the primary vesicle of a case of the inoculated form of the disease, by passage through the system of the calf can be so altered in character as to become deprived of its power of causing a generalized eruption, while inducing at the site of inoculation a vesicle indistinguishable from a typical vaccine vesicle; and, more important still, that when transferred again to man, it has by such treatment completely lost its former infectious character. Such being the case, it may fairly be asserted that cow-pox, or rather that artificially inoculated form of the disease which we term vaccinia, is nothing more nor less than variola modified by transmission through the bovine animal. An outbreak of small-pox, indeed, may be turned to account for raising, by appropriate experimental methods, a fresh stock of vaccine lymph.

There is much evidence to prove that the results following on vaccination are due to a specific contagium, and, moreover, that the particular micro-organism concerned is capable of existing, during one period of its life-cycle, in a resting or spore form, in which condition it is more resistant to the germicidal effects of glycerine than is the case with non-sporing microbes. Advantage is taken of this fact, in the method devised by the present writer, and now employed officially in England, as also on the Continent and in America, for ensuring the bacteriological purity of vaccine lymph. Up to the present, unfortunately, no satisfactory method has been discovered by which the micro-organism of vaccinia can be unfailingly cultivated on artificial media while still retaining its specific properties.

The publication in 1896 of the final report of the English Royal Commission on Vaccination, in which the various phases of the vaccination question are discussed on the basis of evidence Vaccina- obtained from witnesses of all shades of opinion during tion Coln- a period extending over no less than six years, consider- mission, ably simplifies the task of dealing with this subject. The 1889-96. Royal Commission, originally numbering fifteen members,' with Lord Herschell as president, was appointed in May 1889, the 1 The original Commissioners were - Lord Herschell, C. Bradlaugh, Dr Bristowe, Dr Collins, Sir C. Dalrymple, J. S. Dugdale, Q.C., Prof. M. Foster, Sir E. H. Galsworthy, Sir Guyer Hunter, J.Hutchinson, Sir James Paget, J. A. Picton, Sir William Savory, S. Whitbread, F. Meadows White, Q.C. Mr Bradlaugh, Dr Bristowe and Sir William Savory died during the progress of the inquiry. Only one of the vacancies thus caused was filled up, Mr J. A. Bright having been appointed on the death of Mr Bradlaugh.

terms of reference being as follows: " To inquire and report as to - (I) The effect of vaccination in reducing the prevalence of, and mortality from, small-pox. (2) What means, other than vaccination, can be used for diminishing the prevalence of small-pox; and how far such means could be relied on in place of vaccination. (3) The objections made to vaccination on the ground of injurious effects alleged to result therefrom; and the nature and extent of any injurious effects which do, in fact, so result. (4) Whether any, and, if so, what means should be adopted for preventing or lessening the ill effects, if any, resulting from vaccination; and whether, and, if so, by what means, vaccination with animal vaccine should be further facilitated as a part of public vaccination. (5) Whether any alterations should be made in the arrangements and proceedings for securing the performance of vaccination, and, in particular, in the provisions of the Vaccination Acts with respect to prosecutions for non-compliance with the law." The evidence given before the Royal Commission was published at intervals in a series of Blue-books, but, as stated, it was not until August 1896 that the final report made its appearance. As regards the effect of vaccination in reducing the prevalence of, and mortality from, small-pox, the following conclusions were arrived at, Dr Collins and Mr Picton alone dissenting: " (1) That it diminishes the liability to be attacked by the disease. (2) That it modifies the character of the disease and renders it (a) less fatal, and (b) of a milder or less severe type. (3) That the protection it affords against attacks of the disease is greatest during the years immediately succeeding the operation of vaccination. It is impossible to fix with precision the length of this period of highest protection. Though not in all cases the same, if a period is to be fixed, it might, we think, fairly be said to cover in general a period of nine or ten years. (4) That after the lapse of the period of highest protective potency, the efficacy of vaccination to protect against attack rapidly diminishes, but that it is still considerable in the next quinquennium, and possibly never altogether ceases. (5) That its power to modify the character of the disease is also greatest in the period in which its power to protect from attack is greatest, but that its power thus to modify the disease does not diminish as rapidly as its protective influence against attacks, and its efficacy, during the later periods of life, to modify the disease is still very considerable. (6) That re-vaccination restores the protection which lapse of time has diminished, but the evidence shows that this protection again diminishes, and that, to ensure the highest degree of protection which vaccination can give, the operation should be at intervals repeated. (7) That the beneficial effects of vaccination are most experienced by those in whose case it has been most thorough. We think it may fairly be concluded that where the vaccine matter is inserted in three or four places, it is more effectual than when introduced into one or two places only, and that if the vaccination marks are of an area of half a square inch, they indicate a better state of protection than if their area be at all considerably below this." For the evidence, statistical or otherwise, on which these conclusions are based, the Reports of the Royal Commission should be consulted. But reference may here be made to two facts of which proof is overwhelming. (1) Small-pox, in pre-vaccination days a disease of infancy and childhood - like measles at the present day - has in the United Kingdom become a disease mainly of adults. The shifting of age-incidence can only be accounted for by the custom of vaccination in infancy. To this day, when small-pox attacks young unvaccinated children, it is found to be as virulent as, or even more virulent than, small-pox in the unvaccinated at higher ages. On the other hand, small-pox is practically unknown among well-vaccinated children. When, quite exceptionally, such children have been attacked, the disease has been so trivial in character as to be liable to escape recognition altogether. (2) Medical men, nurses and other persons exposed to the disease habitually protect themselves by efficient re-vaccination, and when this precaution has been taken, never contract small-pox.

The clinical activity and bacteriological purity of the lymph employed for vaccination; the skilful performance of the operation itself; the making an adequate number of insertions of lymph over a sufficient area; the observance of precautions needful for ensuring strict asepsis, both at the time of vaccination and subsequently until the vaccination wounds are soundly healed - all these are matters to be regarded as essential to " efficient vaccination." Certain principles in respect of them are generally recognized, and in the case of public vaccinators, whose work comes under government inspection, a series of instructions on these several points are prescribed by the Local Government Board. First in regard to lymph. That which is now almost universally employed in Great Britain is glycerinated calf lymph, the use of which has entirely superseded, in public vaccinations, the arm-to-arm method which for many years previously had been employed as the best means then attainable logy. Efficient tion. of ensuring the activity and comparative purity of the lymph. Glycerinated lymph, under proper conditions, usually retains its potency for many weeks or months; but nevertheless, in certain circumstances at present imperfectly understood, is liable to become gradually weakened, and even eventually to become altogether inert. Possibly the condition of the calves from which the lymph is obtained, especially as regards their general health and the suppleness or the reverse of their skins, or exposure of the lymph to the action of light or to a high temperature, are of special importance. Consequently, in order to ensure the best results from its use, it is not only necessary that great care should be exercised in its manufacture, but it is also advisable that the lymph should be employed for vaccination as soon as possible after bacteriological examination has demonstrated its freedom from suppurative and other extraneous microorganisms. As regards the carrying out of the operation itself, it is somewhat unfortunate that there exists no official definition of what constitutes a " successful vaccination," and in consequence it is open to any practitioner to give a certificate of successful vaccination in cases where but one minute vesicle may have been produced. It is to be feared that such certificates are too frequently given, and it cannot be too strongly urged that vaccination of this sort involves incomplete protection. The standard laid down by the Local Government Board - the production, namely, of a total area of vesiculation of not less than half a square inch, divided among four separate vesicles or groups of vesicles, not less than half an inch from one another - has for the most part proved easily attainable in practice, and it is much to be desired that in private as in public work the attainment of this standard should be aimed at in every instance.

The protection afforded by a primary vaccination tends gradually to diminish, and eventually to disappear more or less completely, with the lapse of time. In consequence, it is desirable that the operation should be repeated at the age of from seven to ten years, and thereafter, if it be possible, at intervals during later life. The final report of the Royal Commission thus summarizes the evidence as to the value of such additional procedure: " Where re-vaccinated persons were attacked by, or died from, small-pox, the re-vaccination had for the most part been performed a considerable number of years before the attack. There were very few cases where a short period only had elapsed between the revaccination and the attack of small-pox. This seems to show that it is of importance, in the case of any persons specially exposed to the risk of contagion, that they should be re-vaccinated, and that in the case even of those who have been twice re-vaccinated with success, if a long interval since the last operation has elapsed, the operation should be repeated for a third, and even a fourth time." It not unfrequently happens that in the case of a re-vaccination the process runs a somewhat different course from that witnessed in a typical primary vaccination. In a successful re-vaccination, the site of the operation may be distinctly reddened and somewhat irritable by the second day, while papules will probably make their appearance about the third to the fifth day. The papules may or may not develop further into vesicles and pustules. Occasionally a re-vaccination appears to fail altogether; but, as pointed out by the Royal Commission, it is advisable, as in the case of a primary vaccination, to make further attempts with lymph of known potency before concluding that the individual is really insusceptible.

In a certain small proportion of cases the operation of vaccination has been followed, after a longer or shorter interAlleged val, by various complications, of which by far the most important are those of an inflammatory nature, effects. such as erysipelas, which are not peculiar to vaccination, but which constitute the danger of any local lesion of the skin, however caused. During the many decades in which vaccination from arm to arm was practised, in many millions of children, a few authenticated cases were recorded in which there was reason to believe that syphilis could have been invaccinated. Such an occurrence could at no time have happened if proper care had been taken by the vaccinator; and now that the use of calf lymph has become practically XXVII. 27 universal, the possibility of such occurrence in the future may be disregarded, since the calf is not capable of contracting this disease. Tubercle in its various forms and leprosy have also been included in the list of possible complications of vaccination, though without any sufficient proof. The employment of calf lymph, treated with glycerine after the manner first advocated by S. Monckton Copeman, will obviate any such danger, for even if tubercle bacilli or the streptococcus of erysipelas were by chance present in the lymph material when collected, it has been found experimentally that they are quite unable to survive prolonged exposure to the action of a 50% solution of glycerine in water. Leprosy is not communicable to the calf. In view of the frequency of various skin eruptions in infancy, it is to be expected that in a proportion of cases they will appear during the weeks following vaccination. Eczema and impetigo in particular have, post hoc, been attributed to vaccination, but no direct connexion has been proved to exist between the operation and the occurrence of these disorders. In section 434 of the final report of the Royal Commission on Vaccination the extent to which other inoculable diseases are liable to complicate vaccination is thus summed up: " A careful examination of the facts which have been brought under our notice has enabled us to arrive at the conclusion that although some of the dangers said to attend vaccination are undoubtedly real, and not inconsiderable in gross amount, yet when considered in relation to the extent of vaccination work done, they are insignificant. There is reason, further, to believe that they are diminishing under the better precautions of the present day, and with the additions of the future precautions which experience suggests, will do so still more in the future." (S. M. C.) j Legislation making vaccination compulsory was first introduced in Bavaria (1807), Denmark (1810), Sweden (1814), Wiirttemburg, Hesse and other German states (1818), Prussia (1835),(1835), the United Kingdom (1853), German empire (1874), Rumania (1874), Hungary (1876), Servia (1881), Austria (1886). But in many cases there had been earlier provisions indirectly making it necessary. In the same way, though there is no federal compulsory law in Switzerland, most of the cantons enforce it; and though there is no statutory compulsion in France, Italy, Spain, Portugal, Belgium, Norway, Russia or Turkey, there are government facilities and indirect pressure, apart from the early popularity of vaccination which made it the usual practice. In the United States there is no federal law, but many of the separate states make their own compulsion either directly or indirectly, Massachusetts starting in 1809.

The benefit of vaccination proved itself in the eyes of the world by its apparent success in stamping out small-pox; but there continued to be people, even of the highest competence, who regarded this as a fallacious argument - post hoc, ergo propter hoc. The cause of " anti-vaccination " has had many followers in England, and their persistence has had important effect in English legislation. Under the provisions of the Vaccination Act 1898, and of the Vaccination Order (1898) of the Local Government Board, with some minor changes in succeeding acts, numerous changes in connexion with vaccina tion administration and with the performance of the operation were introduced, in addition to the super- tegisla- session of arm-to-arm vaccination, by the use of glycerinated calf lymph. Thus, whereas by the Vaccination Acts of 1867 and 1871 the parent or person having the custody of any child was required to procure its vaccination within three months of birth, this period by the act of 1898 was extended to six months. Again, parents were relieved of any penalty under the compulsory clauses of the Vaccination Acts who afforded proof that they had, within four months of the birth of a child, satisfied a stipendiary magistrate, or two justices in petty sessions, that they conscientiously believed that vaccination would be prejudicial to the health of the child. Moreover, proceedings were not to be taken more than twice against a defaulting parent, namely, once under section 29 of the act of 1867, and once under section 31 of the same act, provided that the child had reached the age of four years. Finally, the public vaccinator was now required to visit the homes of children for the purpose of offering vaccination with glycerinated calf lymph, " or such other lymph as may be issued by the Local Government Board." The operative procedure in public vaccinations was formerly based on the necessity of carrying on a weekly series of transferences of vaccine lymph from arm to arm; and for the purposes of such arm-to-arm vaccination the provision of stations, to which children were brought first for the performance of the operation, and again, after a week's interval, for inspection of the results, was an essential. The occasional hardships to the mothers, and a somewhat remote possibility of danger to the children, involved in being taken long journeys to a vaccination station in bad weather, or arising from the collecting together in one room of a number of children and adults, one or more of whom might happen to be suffering at the time from some infectious disorder, are a few of the reasons which appeared to render a change in this regulation desirable; as a matter of fact, it would appear that nothing but good has arisen from the substitution of domiciliary for stational vaccination. There have naturally been some curious discussions before the magistrates as to what is " conscientious " or not, but the working of the so-called " conscience clause " by no means justified the somewhat gloomy forebodings expressed, both in Parliament and elsewhere, at the time of its incorporation in the act of 1898. On the contrary, its operation appeared to tend to the more harmonious working of the Vaccination Acts, by affording a legal method of relief to such parents and guardians as were prepared to affirm that they had a conscientious belief that the performance of the operation might, in any particular instance, be prejudicial to the health of the child.

AuTxoRITIEs

Acland, " Vaccinia," Allbutt and Rolleston, System of Medicine (1906); Baron, Life of Jenner; Henry Colburn (London, 1838); Copeman, Vaccination: Its Natural History and Pathology (Milroy Lectures) (Macmillan, London, 1899); Modern Methods of Vaccination and their Scientific Basis," Trans. Royal Med. and Chir. Society (1901-2); M`Vail, " Criticism of the Dissentient Commissioners' Report," Trans. Epidemiological Society (1897); Reports of the Royal Commission on Vaccination (1889-1896); " The History and Effects of Vaccination," Edinburgh Review, No. 388 (1899); Vaccination Law of German Empire (Berlin, 1904).


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Simple English

[[File:|thumb|right|A child in India is being vaccinated against polio]]

Vaccination means giving someone a vaccine, substance that makes an immune system react. The immune system is the way a body fights infection. The immune system's reaction makes someone less likely to get that infection.

If the vaccinated person get exposed to the virus or bacteria that causes the disease, the person will fight it and may not get sick.

Another word used for using vaccines is immunization. These words mean things that are a little different. Vaccination is when a person is given something to make the immune system learn to fight an infectious disease. Immunization is when a persons immune system learns to fight an infection. Immunization can happen from administration of a vaccine, that is of vaccination. But immunization can also happen from getting the infection. For example, a person can be immune to hepatitis B if he gets sick with hepatitis B. After a person gets hepatitis B and then gets well, he is immunized from getting it again. A person can also be immunized from to hepatitis B by taking the hepatitis B vaccination.

So vaccination and immunization have meanings that are a little different. But when people say these words, they usually mean the same thing. People say immunization to mean the same thing as vaccination.

Contents

Where vaccination comes from

The first use of the term "vaccine" is credited to Dr Edward Jenner. The word is derived from the Latin vacca, meaning cow. A virus that mainly affects cows (Cowpox) was used in the first scientific demonstration that giving a person one virus could protect against a related and more deadly one.

History of vaccination

File:Poster for vaccination against
Poster for vaccination against smallpox.

The first vaccination ever was for smallpox. In 1796 an English doctor, Edward Jenner noticed something. He saw that people who got cowpox did not get sick from smallpox. He gave a young boy the cowpox virus to protect him from smallpox. This was done by scratching liquid from cowpox sores into the boy's skin. This same method using liquid from sores was also used to give people smallpox. People did this so they might get smallpox on one place on their body. Then they could pick which body part got scars from smallpox. But sometimes people who did this got very sick from smallpox. Some even died. This was a dangerous thing to do. But people did it because it was less dangerous then getting smallpox.

Edward Jenner gave the boy cowpox in the same way people tried to give smallpox. Six weeks later, he scratched smallpox into the boy's skin. The boy did not get sick from smallpox. This boy was the first person ever to get a vaccination.

It was not until almost 100 years after the smallpox vaccination that medicine found the next vaccination. In 1879 the vaccine for cholera was found. Since then vaccines for 28 different diseases have been found.

Herd Immunity

Herd immunity is an important part of how vaccines work. A herd is a group of animals. Herd immunity happens when most of the animals in a group are immune to an infection. If most animals are immune they cannot get the disease. If they do not get the disease, they cannot give it to other animals. So even one animal who is not immune is safer. If none of the other animals in a herd get the infection, they cannot give the infection to the one who is non immune.

This is important in people too. If 95% of people in a place are immune to a disease, the other 5% are safer. There will just not be as much of that disease around to get.

The people who are in the 5% are there for many reasons. Some got the vaccine but did not react to it. Their immune system did not learn how to fight it well. Some of them are too sick to get the vaccine. It can be children who are too sick with other diseases to get vaccines. It can be a pregnant woman who cannot get the vaccine because it could hurt her baby. It can be a person with cancer who does not have a strong immune system. It can be an older person who has a weak immune system.

So if everyone in a place gets vaccinated, it protects these people too. If they are not protected by herd immunity, they can get more sick from an infection. They get the infection more easily and they get sicker from it. So it is important that people who are healthy get their vaccinations. It protects the healthy people. But it also is important to protect other people who are old, weak, or sick.

Types of vaccines

There are different types of vaccines:

  1. Inactivated vaccines contain particles (usually viruses). These have been grown for the purpose. They have been killed, using formaldehyde or by other means. But the virus still looks intact; the immune system can develop antigens against it.
  2. Attenuated vaccines contain live viruses, that have been weakened. They will reproduce, but very slowly. Such vaccines cannot be used on patients with a weakened immune system.
  3. Subunit vaccines show antigens to the immune system, without introducing virus material.

Safety of vaccination

Some people argue against vaccination. They believe giving people vaccination causes more sickness than it stops. Today in modern countries, most people are vaccinated. Because most people are vaccinated much fewer people get sick from the infections that vaccines stop. So most people do not think about the risk of getting sick. Many young doctors have not even seen some of these diseases!

Vaccines also can make people very sick. Almost all people who get a vaccination do not get sick from it. Some people get a little sick. They may get fever or feel sick. This gets better in a few days. A very very small number of people can get very sick. So people see that vaccines can make people sick. But they do not see how sick more people would be if we did not vaccinate people. So they only think about the risks vaccines cause. They do not think as much about the risks of not giving vaccinations.

Some people chose not to get vaccinations because of the small risks. Parents may not give their children vaccines. These people also depend on herd immunity. If most children do not get mumps children who do not get the mumps vaccine are also safe. But if enough children do not get the mumps vaccine, or if the vaccine does not work as well as expected, mumps comes back, afflicting older people for whom the disease is more severe. That would be called an epidemiological shift. Then all people who are not immune may get sick. These might be healthy people who chose not to get the vaccine. They might get sick, but will usually get well. Sick people who depend on herd immunity will also get sick. Some may get very sick and even die.

All big medical organizations say that vaccines are safe. They say vaccines stop much more sickness than they make. The World Health Organization, the American Medical Association, the American Academy of Pediatrics, and the United States Centers for Disease Control all support vaccination.

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