Vaccine

2007-11-12T23:28:35Z

Hutchins:

[[Image:Vaccine.jpg|right|thumb|350px|Avian flu vaccine development]]
A '''vaccine''' is an injection of a specialized [[protein]] designed to create an immunity to a particular disease (see [[antigen]]). The primary mechanism that a body uses to identify infections is a protein molecule called an [[antibody]].

If the body has a particular antibody for a particular disease it can identify the infection early on and the [[immune system]] can destroy it. Vaccines work by exposing the body to a form of the disease in such a way that it will not cause illness but allow antibodies to develop. This confers a level of immunity to the organism vaccinated.<ref>http://www.howstuffworks.com/immune-system7.htm How stuff works: Antibodies</ref>

There are four major types of vaccines and they are differentiated by what antigen is used. Live attenuated vaccines are created from the actual disease in question, however before injection the [[pathogen]] is [[attenuated]] (weakened) by growing successive generations of lines in poor nutrient conditions. It is possible for these vaccines to still cause an infection. Inactivated vaccines are created from pathogens that have been killed, usually with the use of a preservative [[formaldehyde]]. Toxoid vaccines are created by using toxins produced by the pathogen, before injection these toxins are exposed to heat and chemicals that eliminate their effect, [[antibodies]] will still be produced to these deactivated toxins. Finally, component vaccines use pieces of the pathogen in the injection. These pieces often of identifying protein segments that allow antibodies to be produced.<ref>http://www.drspock.com/article/0,1510,4866,00.html The Main Types of Vaccine </ref>

Only live attenuated vaccines can still cause infection.The other three types of vaccines can cause illness, but this is an allergic response not due to the disease itself. Very rarely a serious disease known as [[eczema vaccinatum]] can emerge. Vaccines that use pieces of pathogens often use a [[carrier virus]] in the injection. Those with very weak immune systems that are exposed to such a vaccine can become infected with the carrier virus and develop [[eczema]]. A recent case of this was reported in the United States after a military man was vaccinated with small pox and his two year old son became ill. <ref> http://www.associatedcontent.com/article/183349/soldier_infects_toddler_son_with_lifethreatening.html AP article on eczema vaccinatum </ref>

Since the adoption of vaccination, however, many diseases have been curbed. [[Smallpox]], a deadly disease responsible for the deaths of millions, has been mostly eliminated through vaccination. Responsible for an estimated 300 to 500 million deaths worldwide in the 20th century, effective vaccination programs of the 19th and 20th century were effective at curbing the disease, and in 1979 the World Health Organization declared smallpox to be eradicated.

[[Polio]], for example, killed over 3,000 people in the United States in 1952 [http://www.cdc.gov/nchs/data/vsus/VSUS_1952_2.pdf], and inflicted such noted persons as President [[Franklin Delano Roosevelt]], actor [[Alan Alda]], and musician [[Itzak Perlman]]. When doctors began using a vaccine to fight polio, it practically eradicated the disease in the developed world.

Other diseases that have been curbed since the invention of vaccines include [[measles]], [[mumps]], [[rubella]], and [[typhoid]].

== Influenza Vaccine and microevolution==

The flu vaccine is an excellent example of modern vaccination. Due to the change in [[allele]] frequency over time in the population of the influenza virus, which scientists describe as microevolution, new influenza vaccines are created each year. According to the [http://www.cdc.gov/ CDC] <ref>"Inactivated Influenza Vaccine, What you need to know," a publication of the Center for Disease Control, 2006. Available online at: http://www.cdc.gov/nip/publications/VIS/vis-flu.pdf</ref>,
<blockquote>
Influenza viruses are always changing. Therefore, influenza vaccines are updated every year, and an annual vaccination is recommended.
</blockquote>
Since production of the vaccine must begin many months before the influenza season starts models of the population genetics of the virus must be produced. <ref>http://www.nature.com/nrd/journal/v5/n3/full/nrd1988.html Influenza vaccines </ref> The success of vaccinations programs in the face of rapid microevolution of the influenza virus is dependent on the accuracy of these predictions.<ref>http://www.nature.com/news/2003/030324/full/030324-5.html Flue evolution modeled </ref> The [[National Institute of Health]] recently assigned $26 million dollars to establish a research center to better develop molecular models of influenza. <ref> http://www.spiritindia.com/health-care-news-articles-8024.html $26 million NIH contract to establish new flu/bird flu Center of Excellence </ref>

==Herd immunity and mandatory vaccination==

An important concept in vaccine planning is [[herd immunity]]. This is the idea that when a certain percentage of a population is vaccinated, those within the population who are not vaccinated are protected from the disease. This is a fairly straight forward concept; if 90 percent of a population is immune, then the chances that a carrier of the disease will come into contact with a non-immune member of the population (or "herd") is low. <ref>http://www.mathepi.com/maindir/herd.html The mathematics of herd immunity</ref>. Herd immunity is the goal of most vaccination programs as it is the point where a disease can start to be eliminated altogether from a population.

For example, in 1962 Japan instituted mandatory vaccination against influenza in school children. This continued until 1987 when the program was changed to optional; it was abandoned in 1994. Approximately 85 percent of children were estimated to have been vaccinated. <ref>http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=387431 Control of Influenza </ref> Several studies examined the mortality rates due to influenza during this period of time and revealed that the death rates due to influenza in all population groups was drastically decreased, including older adult populations. Since there was no increased rate of vaccination in these populations, the decreased mortality was caused by herd immunity effects of vaccinating so many children. <ref>http://www.newsrx.com/newsletters/Vaccine-Weekly/2001-04-11/200104113335VW.html Mandatory Vaccination of Japanese Schoolchildren Demonstrates "Herd Immunity" </ref> Many researchers have written that this and other evidence argues strongly for mandatory vaccination programs world wide as a means of controlling many diseases and preventing a [[pandemic]].<ref> http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1360502 Herd Immunity</ref>

The USA has mandatory vaccination according to an official CDC schedule. Enforcement is left to the states. Most states have medical and religious exemptions. Some states make it very easy to opt out of vaccines, while other states strictly enforce compliance for school attendance. The difference in vaccination rates between these states is actually very slight, and not nearly enough to affect herd immunity.

== Adverse Reactions ==
Vaccines are not completely harmless, and many have a significant morbidity and mortality associated with them. Postvaccinial encephalitis is a known hazard of [[smallpox]] vaccine, for example. A recently-introduced vaccine against [[human papilloma virus]], the [[causative agent]] of [[cancer]] of the [[uterus|uterine]] [[cervix]], has now been linked to a number of sudden deaths reported within days of its administration.<ref name=GardasilMM>Cockcroft, Lucy, "[http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/10/29/njab129.xml Cervical cancer drug Gardasil linked to deaths]," ''[[London]] Daily Telegraph'', October 29, 2007. Retrieved November 10, 2007.</ref>

==References==
<references/>

[[Category:Biology]]
[[Category:Medicine]]

Panzerschreck

2007-11-11T16:23:59Z

Hutchins: New page: Panzerschreck (German: tank terrorizer) was the popular name for the Raketenpanzerbüchse ('rocket tank rifle', abbreviated to RPzB), an 88 mm calibre reusable anti-tank rocket launcher de...

Panzerschreck (German: tank terrorizer) was the popular name for the Raketenpanzerbüchse ('rocket tank rifle', abbreviated to RPzB), an 88 mm calibre reusable anti-tank rocket launcher developed by the Germans in World War II. Another popular nick-name was Ofenrohr ("stove pipe").

It was given to infantry to bolster their anti-tank capability. The weapon was shoulder-launched and fired a rocket-propelled, fin-stabilized grenade with a shaped charge warhead. It was made in much smaller numbers than the Panzerfaust, which was a disposable recoilless rifle firing an anti-tank grenade.

The weapon was created in response to the incredible success of the Allied "Bazooka" against German armor, outshining the penetration, accuracy and range of the German antitank grenades. After being reverse-engineered in Germany, the first Panzerschreck model, RPzB 43, began to roll off assembly lines.

The bazooka rocket fielded by the Allies often had trouble penetrating German 100mm armor, especially on the Tiger tank. The Panzerschreck's rocket, however, could easily ppenetrate over 200mm of armor plate, making it suitable for penetrating heavy Soviet armor. Panzerschrecks soon became the bane of Allied vehicle commanders, as the Panzerschreck often destroyed any armored fighting vehicle in one shot.

Notable drawbacks of the weapon include a heavier and more cumbersome design than the bazooka, as well as the smokey nature of the propellant used in the rocket. While the Panzerfaust used a short-burst motor, producing relatively little smoke, the Panzerschreck's motor produced great volumes of smoke. This was to the disadvantage of rocket troops fielding them, as it instantly gave away their position, and could not be used indoors because the room the rocket was fired from would be quickly filled with toxic fumes.

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Vaccine

Panzerschreck