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{{Small pox]]
{{Smallpox}}
{{CMG}}
{{CMG}}; {{AE}} {{JS}}


==Overview==
==Overview==
The smallpox vaccine helps the body develop [[immunity]] to smallpox. The vaccine         is made from a virus called vaccinia which is a “pox”-type virus        related to smallpox. The smallpox vaccine contains the “live”        vaccinia virus—not dead [[virus]] like many other vaccines. For that reason,         the vaccination site must be cared for carefully to prevent the virus from        spreading. Also, the vaccine can have [[side effects]]. The vaccine does not contain        the smallpox virus and cannot give you smallpox.
[[Primary prevention]] of [[smallpox]] consists in the administration of the ''vaccinia [[vaccine]]'', which attenuates or suppresses the manifestations of the disease, if administrated soon after [[infection]] has occurred. In the absence of an [[outbreak]], the [[vaccine]] is only administered to clinical and/or laboratory workers dealing with the [[smallpox virus|virus]] in specialized laboratories. It has several adverse effects, particularly in [[immunosuppressed]] individuals, those with [[heart]] conditions or [[allergies]], for whom its administration must be guided by specific rules.


Currently, the United States has a big enough stockpile of smallpox vaccine to vaccinate everyone in the United States in the event of a smallpox emergency.
==Primary Prevention==
The administration of the [[vaccine]] can attenuate, sometimes prevent, the manifestations of [[smallpox]]. The [[vaccine]] is made from a [[virus]] called vaccinia which is a “pox”-type [[virus]] related to [[smallpox]]. The [[vaccine]] does not contain the [[smallpox virus]] and therefore cannot transmit [[smallpox]]. However, it contains the “live” vaccinia [[virus]], not a dead [[virus]] like many others, for which the [[vaccination]] site must be cared for carefully, in order to prevent the [[virus]] from spreading.<ref name="BremanHenderson2002">{{cite journal|last1=Breman|first1=Joel G.|last2=Henderson|first2=D.A.|title=Diagnosis and Management of Smallpox|journal=New England Journal of Medicine|volume=346|issue=17|year=2002|pages=1300–1308|issn=0028-4793|doi=10.1056/NEJMra020025}}</ref> The [[vaccine]] is given in the upper arm, using a bifurcated needle, that is dipped into the [[vaccine]] solution. When removed, the needle retains a droplet of the [[vaccine]]. It is used to prick the [[skin]] a number of times in a few seconds. The pricking is not deep, reaching basilar [[epithelium]], but it will cause a sore spot and one or two droplets of [[blood]] will be formed.<ref name=CDC3>{{cite web | title = Emergence preparedness and response | url = http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp }}</ref>


==Vaccination history==
If the [[vaccination]] is successful, 1 or 2 droplets of [[blood]] will be formed within the site of the [[vaccine]], a few seconds after administration, and a [[cellular]] reaction will then occur. This will lead to the formation of the ''Jennerian pustule'' (1-2 cm), considered to be the ''major reaction''. The ''Jennerian pustule'' is a sign of successful [[vaccination]], which leads to full [[immunity]] in more than 95% of cases, possibly for 5 to 10 years.
At the age of thirteen, Jenner was apprenticed to Dr. Ludlow in Sodbury. He observed that people who caught [[cowpox]] while working with cows were known not to catch smallpox.  He assumed a causal connection. The idea was not taken up by Dr. Ludlow at that time.  After Jenner returned from medical school in London, a smallpox [[epidemic]] struck his home town of Berkeley, England. He advised the local cow workers to be inoculated. The farmers told him that cowpox prevented smallpox. This confirmed his childhood suspicion, and he studied cowpox further, presenting a paper on it to his local medical society.


Perhaps there was already an informal public understanding of some connection between [[disease]] resistance and working with cows.  The “beautiful milkmaid” seems to have been a frequent image in the art and literature of this period. But we know for a fact: In the years following 1770 there were at least six people in England and Germany (Sevel, Jensen, Jesty 1774, Rendall, Plett 1791), who tested successfully the possibility of using the cowpox vaccine as an [[immunization]] for smallpox in humans. In 1796 Sarah Nelmes, a local milkmaid, contracted cowpox and went to Jenner for treatment. Jenner took the opportunity to test his theory.  He inoculated James Phipps, the eight-year-old son of his gardener, not with smallpox but with cowpox. After an extremely weak bout of cowpox, James recovered. Jenner then tried to infect James with smallpox but nothing happened—the boy was immune to smallpox.
Below is the progression of the appearance of the local of administrations of the [[vaccine]]: a red and [[itchy]] bump develops at the [[vaccine]] site within 3 to 4 days. During the first week, the bump becomes a large [[blister]], fills with [[pus]], and begins to drain. During the second week, the blister begins to dry up and a [[scab]] is formed. The scab then falls off during the third week, leaving a small [[scar]].<ref name=CDC3>{{cite web | title = Emergence preparedness and response | url = http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp }}</ref>
Thanks to the development of the smallpox [[vaccine]], the disease was officially eradicated in 1979.


Jenner reported his observations to the Royal Society. Further work was suggested, and Jenner published a series of 23 cases, including his son Edward, none suffered severely from smallpox<!-- did any contract it at all? -->. Two years later a society to oppose vaccination had been established in Boston, Massachusetts — an indication of rapid spread and deep interest. By 1800 Jenner’s work had been published in all of the major European languages. The process was performed all over Europe and the United States. The death rate was close to zero with the process, which became known as [[vaccination]] and was continued to around 1974 in the UK. A typical death rate at that time was roughly one per million, making vaccination against smallpox with [[vaccinia]] the most dangerous immunisation widely provided in modern times.
[[Image:Smallpox vaccine.jpg|thumb|center|500px|<SMALL><SMALL>''[http://www.bt.cdc.gov/agent/smallpox/smallpox-images/vaxsit5a.htm  Adapted from Centers for Disease Control and Prevention (CDC), Centers for Disease Control and Prevention.]''<ref name="CDC">{{Cite web | title = Centers for Disease Control and Prevention (CDC) | url = http://www.bt.cdc.gov/agent/smallpox/smallpox-images/vaxsit5a.htm}}</ref></SMALL></SMALL>]]


The [[Balmis Expedition]] (1803) carried the vaccine to Spanish America, the Philippines and China under commission of the Spanish Crown.
People who were [[vaccinated]] prior to 1972, if revaccinated, may experience accelerated [[immune response]].


Some years before Dr. Jenner, [[Benjamin Jesty]], a farmer at Yetminster in Dorset (he later moved to and is buried at Worth Matravers) is recorded as observing the two milkmaids living with his family to have been immune to smallpox and then inoculating his family with cowpox to protect them from smallpox. This was done in 1774 and can be found with Crookshank's History and Pathology of Vaccination, London 1889, vol. 1, p.110ff. But the question of who first initiated smallpox inoculation/vaccination can not be answered properly, as there is in the sources the exact date and time only for the predecessor Plett (1791), but not for Sevel, Jensen and Rendall.
===Vaccine Generation===
Louis T. Wright,<ref name=North_by_South>{{cite web | title=A Brief Biography of Dr. Louis T. Wright | work=North by South: from Charleston to Harlem, the great migration | url=http://northbysouth.kenyon.edu/1998/health/wright.htm | accessdate=2006-09-23}}</ref> an African-American and Harvard medical school graduate (1915), introduced intradermal vaccination for smallpox for the soldiers while serving in the Army during World War I.<ref name=MITRE_CDAC>{{cite web | title=Spotlight on Black Inventors, Scientists, and Engineers | work=Department of Computer Science of Georgetown University | url=http://www.cs.georgetown.edu/~blakeb/mm/BHM/Spotlight%20on%20Black%20Inventors,%20Scientists,%20and%20Engineers.htm | accessdate=2006-09-23}}</ref>
Three generations of [[vaccines]] have been developed so far:
* ''1st generation'' - a mixture of related [[virus]]es, which differ from the remaining [[orthopoxvirus]]es. Reactions to these generation include:<ref name="BremanHenderson2002">{{cite journal|last1=Breman|first1=Joel G.|last2=Henderson|first2=D.A.|title=Diagnosis and Management of Smallpox|journal=New England Journal of Medicine|volume=346|issue=17|year=2002|pages=1300–1308|issn=0028-4793|doi=10.1056/NEJMra020025}}</ref><ref name="pmid13974310">{{cite journal| author=ROBERTS JA| title=Histopathogenesis of mousepox. I. Respiratory infection. | journal=Br J Exp Pathol | year= 1962 | volume= 43 | issue=  | pages= 451-61 | pmid=13974310 | doi= | pmc=PMC2095140 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=13974310  }} </ref><ref name="MooreSeward2006">{{cite journal|last1=Moore|first1=Zack S|last2=Seward|first2=Jane F|last3=Lane|first3=J Michael|title=Smallpox|journal=The Lancet|volume=367|issue=9508|year=2006|pages=425–435|issn=01406736|doi=10.1016/S0140-6736(06)68143-9}}</ref>
:* [[Fever]]
:* Regional [[swelling]]
:* [[Edema]]
:* [[Headache]]
:* Painful [[lymphadenitis]]


==Current vaccine==
* ''2nd generation'' - individual vaccinia clones, derived from [[virus]]es which are genetically similar, to the ones that made the 1st generation vaccine. This generation had a more efficient production of the [[vaccine]].<ref name="MooreSeward2006">{{cite journal|last1=Moore|first1=Zack S|last2=Seward|first2=Jane F|last3=Lane|first3=J Michael|title=Smallpox|journal=The Lancet|volume=367|issue=9508|year=2006|pages=425–435|issn=01406736|doi=10.1016/S0140-6736(06)68143-9}}</ref><ref name="pmid15014500">{{cite journal| author=Earl PL, Americo JL, Wyatt LS, Eller LA, Whitbeck JC, Cohen GH et al.| title=Immunogenicity of a highly attenuated MVA smallpox vaccine and protection against monkeypox. | journal=Nature | year= 2004 | volume= 428 | issue= 6979 | pages= 182-5 | pmid=15014500 | doi=10.1038/nature02331 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15014500  }} </ref>


===Length of protection===
* ''3rd generation'' - developed from the attenuated vaccinia strains, after [[genetic]] manipulation or multiple passage through non-human tissue. Contains [[strains]] not as virulent as previous generations, and therefore safer, mainly because of a delay in replication of the [[virus]].<ref name="MooreSeward2006">{{cite journal|last1=Moore|first1=Zack S|last2=Seward|first2=Jane F|last3=Lane|first3=J Michael|title=Smallpox|journal=The Lancet|volume=367|issue=9508|year=2006|pages=425–435|issn=01406736|doi=10.1016/S0140-6736(06)68143-9}}</ref><ref name="pmid15014500">{{cite journal| author=Earl PL, Americo JL, Wyatt LS, Eller LA, Whitbeck JC, Cohen GH et al.| title=Immunogenicity of a highly attenuated MVA smallpox vaccine and protection against monkeypox. | journal=Nature | year= 2004 | volume= 428 | issue= 6979 | pages= 182-5 | pmid=15014500 | doi=10.1038/nature02331 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15014500  }} </ref><ref name="pmid11395204">{{cite journal| author=Stittelaar KJ, Kuiken T, de Swart RL, van Amerongen G, Vos HW, Niesters HG et al.| title=Safety of modified vaccinia virus Ankara (MVA) in immune-suppressed macaques. | journal=Vaccine | year= 2001 | volume= 19 | issue= 27 | pages= 3700-9 | pmid=11395204 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11395204  }} </ref><ref name="pmid1566575">{{cite journal| author=Tartaglia J, Perkus ME, Taylor J, Norton EK, Audonnet JC, Cox WI et al.| title=NYVAC: a highly attenuated strain of vaccinia virus. | journal=Virology | year= 1992 | volume= 188 | issue= 1 | pages= 217-32 | pmid=1566575 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1566575  }} </ref>
Smallpox vaccination provides high level [[immunity]] for 3        to 5 years and decreasing immunity thereafter. If a person is vaccinated        again later, immunity lasts even longer. Historically, the [[vaccine]] has        been effective in preventing smallpox infection in 95% of those vaccinated.         In addition, the vaccine was proven to prevent or substantially lessen        infection when given within a few days of exposure. It is important to        note, however, that at the time when the smallpox vaccine was used to        eradicate the [[disease]], testing was not as advanced or precise as it is        today, so there may still be things to learn about the vaccine and its      effectiveness and length of protection.


===Receiving the vaccine===
===Vaccine Recommendations===
Since [[smallpox]] was declared eradicated, [[vaccination]] is not advised for common citizens. The only people with formal indication for ''vaccinia vaccine'' are the laboratory or clinical individuals who work with the [[smallpox virus|virus]] at specialized laboratories.<ref name="BremanHenderson2002">{{cite journal|last1=Breman|first1=Joel G.|last2=Henderson|first2=D.A.|title=Diagnosis and Management of Smallpox|journal=New England Journal of Medicine|volume=346|issue=17|year=2002|pages=1300–1308|issn=0028-4793|doi=10.1056/NEJMra020025}}</ref>


The smallpox vaccine is not given with a [[hypodermic needle]].        It is not a [[shot]] as most people have experienced. The vaccine is given        using a [[bifurcated]] (two-pronged) needle that is dipped into the vaccine        solution. When removed, the needle retains a droplet of the vaccine. The        needle is used to prick the skin a number of times in a few seconds. The        pricking is not deep, but it will cause a sore spot and one or two droplets        of [[blood]] to form. The vaccine usually is given in the upper [[arm]].
===Vaccine Adverse Events===
The following adverse events to the [[vaccine]] have been reported:<ref name="MooreSeward2006">{{cite journal|last1=Moore|first1=Zack S|last2=Seward|first2=Jane F|last3=Lane|first3=J Michael|title=Smallpox|journal=The Lancet|volume=367|issue=9508|year=2006|pages=425–435|issn=01406736|doi=10.1016/S0140-6736(06)68143-9}}</ref><ref name="pmid12824210">{{cite journal| author=Halsell JS, Riddle JR, Atwood JE, Gardner P, Shope R, Poland GA et al.| title=Myopericarditis following smallpox vaccination among vaccinia-naive US military personnel. | journal=JAMA | year= 2003 | volume= 289 | issue= 24 | pages= 3283-9 | pmid=12824210 | doi=10.1001/jama.289.24.3283 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12824210  }} </ref><ref name="Arness2004">{{cite journal|last1=Arness|first1=M. K.|title=Myopericarditis following Smallpox Vaccination|journal=American Journal of Epidemiology|volume=160|issue=7|year=2004|pages=642–651|issn=0002-9262|doi=10.1093/aje/kwh269}}</ref><ref name="pmid14585633">{{cite journal| author=Chen RT, Lane JM| title=Myocarditis: the unexpected return of smallpox vaccine adverse events. | journal=Lancet | year= 2003 | volume= 362 | issue= 9393 | pages= 1345-6 | pmid=14585633 | doi=10.1016/S0140-6736(03)14674-0 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14585633  }} </ref>
* Fetal vaccinia
* Progressive vaccinia
* Generalized vaccinia
* Non-specific [[rashes]]
* [[Eczema vaccinatum]]
* [[Encephalitis]]
* [[Myopericarditis]]


If the vaccination is successful, a red and [[itchy]] bump        develops at the vaccine site in three or four days. In the first week,        the bump becomes a large [[blister]], fills with [[pus]], and begins to drain.        During the second week, the blister begins to dry up and a [[scab]] forms.        The scab falls off in the third week, leaving a small [[scar]]. People who        are being vaccinated for the first time have a stronger reaction than        those who are being revaccinated. The following pictures show the progression        of the site where the vaccine is given.
===Vaccine Contraindications===
In the absence of reintroduction of [[smallpox]], [[vaccination]] is contraindicated in the following:<ref name="MooreSeward2006">{{cite journal|last1=Moore|first1=Zack S|last2=Seward|first2=Jane F|last3=Lane|first3=J Michael|title=Smallpox|journal=The Lancet|volume=367|issue=9508|year=2006|pages=425–435|issn=01406736|doi=10.1016/S0140-6736(06)68143-9}}</ref><ref name=CDC2>{{cite web | title = Recommendations for Using Smallpox Vaccine in a Pre-Event Vaccination Program
| url = http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5207a1.htm }}</ref>
* Patients with [[allergy]] to [[vaccine]] components
* History of [[atopic dermatitis]]
* History of exfoliative [[skin]] disorders
* [[Inflammatory]] eye disorders
* [[Immunosuppressed]] patients
* [[Heart disease]]
* [[Pregnancy]]
* Disease cases in the family
* Children <1 year
* [[Breastfeeding]]


[[Image:Smallpox vaccine.jpg]]
====Post-Vaccination====
After [[vaccination]] it is important to follow instructions for the care of the [[vaccine]] site. Because the [[virus]] is alive, it can spread to other parts of the body, or to other people. The [[vaccinia virus]] may cause:<ref name=CDC3>{{cite web | title = Emergence preparedness and response | url = http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp }}</ref>
* [[Rash]]
* [[Fever]]
* [[Headache]]
* [[Body]] pain
Elderly and pregnant women are prone to severe [[complications]] following the [[vaccinia virus]] vaccine.


===Post-vaccination===
====Vaccine Benefit====
After vaccination, it is important to follow care instructions        for the site of the vaccine. Because the virus is live, it can spread        to other parts of the body, or to other people. The vaccinia virus (the        live virus in the smallpox vaccine) may cause [[rash]], [[fever]], and [[head]] and        [[body]] [[aches]]. In certain groups of people, complications from the       [[vaccinia]] virus can be severe.
[[Vaccination]] within 3 days of exposure will prevent or significantly lessen the severity of [[smallpox]] [[symptoms]] in the vast majority of people. [[Vaccination]] 4 to 7 days after exposure likely offers some protection from the disease or may modify its severity.<ref name=CDC3>{{cite web | title = Emergence preparedness and response | url = http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp }}</ref>


===Vaccine benefit===
===Vaccine===
Vaccination within 3 days of exposure will prevent or significantly          lessen the severity of smallpox symptoms in the vast majority of people.          Vaccination 4 to 7 days after exposure likely offers some protection from        disease or may modify the severity of disease.
The algorithm below demonstrates the action protocol in the presence of a patient who appears to show an adverse reaction to the [[smallpox]] vaccine.<ref name=CDC3>{{cite web | title = Emergence preparedness and response | url = http://www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp }}</ref>


===Safety===
[[Image:Smallpox lab vaccine.jpg|thumb|center|800px|<SMALL><SMALL>''[http://emergency.cdc.gov/agent/smallpox/diagnosis/pdf/poxalgorithm5-2-14.pdf  Adapted from Laboratory Response Network (LRN [CDC]), Laboratory Response Network.]''<ref name="LRN(CDC)">{{Cite web | title = Public Health Image Library (PHIL), Centers for Disease Control and Prevention | url = http://emergency.cdc.gov/agent/smallpox/diagnosis/pdf/poxalgorithm5-2-14.pdf}}</ref></SMALL></SMALL>]]
The smallpox vaccine is the best protection you can get        if you are exposed to the smallpox virus. Anyone directly exposed to smallpox,         regardless of health status, would be offered the smallpox vaccine because        the risks associated with smallpox disease are far greater than those        posed by the vaccine.


There are side effects and risks associated with the smallpox        vaccine. Most people experience normal, usually mild reactions that include        a sore [[arm]], [[fever]], and [[body aches]]. However, other people experience reactions        ranging from serious to life-threatening. People most likely to have serious        side effects are: people who have had, even once, skin conditions (especially        eczema or atopic dermatitis) and people with weakened [[immune systems]],        such as those who have received a transplant, are [[HIV]] positive, are receiving        treatment for [[cancer]], or are currently taking [[medications]] (like [[steroids]])        that suppress the [[immune system]]. In addition, [[pregnant]] women should not        get the vaccine because of the risk it poses to the [[fetus]]. Women who are        [[breastfeeding]] should not get the vaccine. Children younger than 12 months        of age should not get the vaccine. Also, the Advisory Committee on Immunization        Practices (ACIP) advises against non-emergency use of smallpox vaccine        in children younger than 18 years of age. In addition, those [[allergic]]        to the vaccine or any of its components should not receive the vaccine.        Also, people who have been diagnosed by a doctor as having a [[heart]] condition        with or without symptoms, including conditions such as previous [[myocardial        infarction]] (heart attack), [[angina]] (chest pain caused by lack of blood        flow to the heart), [[congestive heart failure]], and [[cardiomyopathy]] (heart        muscle becomes inflamed and doesn’t work as well as it should),        [[stroke]] or [[transient ischemic attack]] (a “mini-stroke” that        produces stroke-like [[symptoms]] but not lasting damage), [[chest]] [[pain]] or [[shortness        of breath]] with activity (such as walking up stairs), or other heart conditions        being treated by a doctor should not get the vaccine at this time. (Heart        disease may be a temporary exclusion and may change as more information        is gathered.) Also, individuals who have 3 or more of the following risk        factors should not get the vaccine at this time: high [[blood pressure]] diagnosed        by a doctor; high blood [[cholesterol]] diagnosed by a doctor; [[diabetes]] or        high blood sugar diagnosed by a doctor; a first degree relative (for example,        mother, father, brother or sister) with a heart condition before the age        of 50; and/or, currently a [[cigarette]] smoker. (These may be temporary exclusions        and may change as more information is gathered.)
==References==
{{Reflist|2}}


In the past, about 1,000 people for every 1 million people        vaccinated for the first time experienced reactions that, while not life-threatening,        were serious. These reactions included a [[toxic]] or allergic reaction at        the site of the vaccination ([[erythema multiforme]]), spread of the vaccinia        virus to other parts of the body and to other individuals (inadvertent        [[inoculation]]), and spread of the vaccinia virus to other parts of the body        through the blood (generalized vaccinia). These types of reactions may        require medical attention. In the past, between 14 and 52 people out of        every 1 million people vaccinated for the first time experienced potentially        life-threatening reactions to the vaccine. Based on past experience, it        is estimated that 1 or 2 people in 1 million who receive the vaccine may        die as a result. Careful screening of potential vaccine recipients is        essential to ensure that those at increased risk do not receive the vaccine.
[[Category:Disease]]


===Availability===
[[Category:Pediatrics]]
Routine smallpox vaccination among the American public        stopped in 1972 after the disease was eradicated in the United States.        Until recently, the U.S. government provided the vaccine only to a few        hundred scientists and medical professionals working with smallpox and        similar viruses in a research setting.
[[Category:Smallpox]]
 
[[Category:Viral diseases]]
After the events of September and October, 2001, however,        the U.S. government took further actions to improve its level of preparedness        against terrorism. One of many such measures—designed specifically        to prepare for an intentional release of the smallpox virus—included        updating and releasing a smallpox response plan.  In addition, the U.S. government has enough vaccine to vaccinate every person in the United States in the event of a smallpox emergency.
[[Category:Poxviruses]]
 
==References==
{{reflist|2}}


{{WH}}
{{WH}}
{{WS}}
{{WS}}
[[Category:Disease]]
[[Category:Infectious disease]]
[[Category:Pediatrics]]

Latest revision as of 19:05, 18 September 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

Primary prevention of smallpox consists in the administration of the vaccinia vaccine, which attenuates or suppresses the manifestations of the disease, if administrated soon after infection has occurred. In the absence of an outbreak, the vaccine is only administered to clinical and/or laboratory workers dealing with the virus in specialized laboratories. It has several adverse effects, particularly in immunosuppressed individuals, those with heart conditions or allergies, for whom its administration must be guided by specific rules.

Primary Prevention

The administration of the vaccine can attenuate, sometimes prevent, the manifestations of smallpox. The vaccine is made from a virus called vaccinia which is a “pox”-type virus related to smallpox. The vaccine does not contain the smallpox virus and therefore cannot transmit smallpox. However, it contains the “live” vaccinia virus, not a dead virus like many others, for which the vaccination site must be cared for carefully, in order to prevent the virus from spreading.[1] The vaccine is given in the upper arm, using a bifurcated needle, that is dipped into the vaccine solution. When removed, the needle retains a droplet of the vaccine. It is used to prick the skin a number of times in a few seconds. The pricking is not deep, reaching basilar epithelium, but it will cause a sore spot and one or two droplets of blood will be formed.[2]

If the vaccination is successful, 1 or 2 droplets of blood will be formed within the site of the vaccine, a few seconds after administration, and a cellular reaction will then occur. This will lead to the formation of the Jennerian pustule (1-2 cm), considered to be the major reaction. The Jennerian pustule is a sign of successful vaccination, which leads to full immunity in more than 95% of cases, possibly for 5 to 10 years.

Below is the progression of the appearance of the local of administrations of the vaccine: a red and itchy bump develops at the vaccine site within 3 to 4 days. During the first week, the bump becomes a large blister, fills with pus, and begins to drain. During the second week, the blister begins to dry up and a scab is formed. The scab then falls off during the third week, leaving a small scar.[2]

Adapted from Centers for Disease Control and Prevention (CDC), Centers for Disease Control and Prevention.[3]

People who were vaccinated prior to 1972, if revaccinated, may experience accelerated immune response.

Vaccine Generation

Three generations of vaccines have been developed so far:

  • 2nd generation - individual vaccinia clones, derived from viruses which are genetically similar, to the ones that made the 1st generation vaccine. This generation had a more efficient production of the vaccine.[5][6]
  • 3rd generation - developed from the attenuated vaccinia strains, after genetic manipulation or multiple passage through non-human tissue. Contains strains not as virulent as previous generations, and therefore safer, mainly because of a delay in replication of the virus.[5][6][7][8]

Vaccine Recommendations

Since smallpox was declared eradicated, vaccination is not advised for common citizens. The only people with formal indication for vaccinia vaccine are the laboratory or clinical individuals who work with the virus at specialized laboratories.[1]

Vaccine Adverse Events

The following adverse events to the vaccine have been reported:[5][9][10][11]

Vaccine Contraindications

In the absence of reintroduction of smallpox, vaccination is contraindicated in the following:[5][12]

Post-Vaccination

After vaccination it is important to follow instructions for the care of the vaccine site. Because the virus is alive, it can spread to other parts of the body, or to other people. The vaccinia virus may cause:[2]

Elderly and pregnant women are prone to severe complications following the vaccinia virus vaccine.

Vaccine Benefit

Vaccination within 3 days of exposure will prevent or significantly lessen the severity of smallpox symptoms in the vast majority of people. Vaccination 4 to 7 days after exposure likely offers some protection from the disease or may modify its severity.[2]

Vaccine

The algorithm below demonstrates the action protocol in the presence of a patient who appears to show an adverse reaction to the smallpox vaccine.[2]

Adapted from Laboratory Response Network (LRN [CDC), Laboratory Response Network.][13]

References

  1. ↑ 1.0 1.1 1.2 Breman, Joel G.; Henderson, D.A. (2002). "Diagnosis and Management of Smallpox". New England Journal of Medicine. 346 (17): 1300–1308. doi:10.1056/NEJMra020025. ISSN 0028-4793.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 "Emergence preparedness and response".
  3. ↑ "Centers for Disease Control and Prevention (CDC)".
  4. ↑ ROBERTS JA (1962). "Histopathogenesis of mousepox. I. Respiratory infection". Br J Exp Pathol. 43: 451–61. PMC 2095140. PMID 13974310.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Moore, Zack S; Seward, Jane F; Lane, J Michael (2006). "Smallpox". The Lancet. 367 (9508): 425–435. doi:10.1016/S0140-6736(06)68143-9. ISSN 0140-6736.
  6. ↑ 6.0 6.1 Earl PL, Americo JL, Wyatt LS, Eller LA, Whitbeck JC, Cohen GH; et al. (2004). "Immunogenicity of a highly attenuated MVA smallpox vaccine and protection against monkeypox". Nature. 428 (6979): 182–5. doi:10.1038/nature02331. PMID 15014500.
  7. ↑ Stittelaar KJ, Kuiken T, de Swart RL, van Amerongen G, Vos HW, Niesters HG; et al. (2001). "Safety of modified vaccinia virus Ankara (MVA) in immune-suppressed macaques". Vaccine. 19 (27): 3700–9. PMID 11395204.
  8. ↑ Tartaglia J, Perkus ME, Taylor J, Norton EK, Audonnet JC, Cox WI; et al. (1992). "NYVAC: a highly attenuated strain of vaccinia virus". Virology. 188 (1): 217–32. PMID 1566575.
  9. ↑ Halsell JS, Riddle JR, Atwood JE, Gardner P, Shope R, Poland GA; et al. (2003). "Myopericarditis following smallpox vaccination among vaccinia-naive US military personnel". JAMA. 289 (24): 3283–9. doi:10.1001/jama.289.24.3283. PMID 12824210.
  10. ↑ Arness, M. K. (2004). "Myopericarditis following Smallpox Vaccination". American Journal of Epidemiology. 160 (7): 642–651. doi:10.1093/aje/kwh269. ISSN 0002-9262.
  11. ↑ Chen RT, Lane JM (2003). "Myocarditis: the unexpected return of smallpox vaccine adverse events". Lancet. 362 (9393): 1345–6. doi:10.1016/S0140-6736(03)14674-0. PMID 14585633.
  12. ↑ "Recommendations for Using Smallpox Vaccine in a Pre-Event Vaccination Program".
  13. ↑ "Public Health Image Library (PHIL), Centers for Disease Control and Prevention" (PDF).

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