Changes

==Herd immunity and mandatory vaccination==

==Herd immunity and mandatory vaccination==

A concept in vaccine planning is "[[herd immunity]]". When a certain percentage of a population is vaccinated, those within the population who are not vaccinated are protected from the disease. 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.  

A concept in vaccine planning is "[[herd immunity]]". When a certain percentage of a population is vaccinated, those within the population who are not vaccinated are protected from the disease. 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 from a population altogether.  

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>{{hnb|Glezen|2004}}</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 worldwide as a means of controlling many diseases and preventing a [[pandemic]].<ref>http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1360502 Herd Immunity</ref>

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>{{hnb|Glezen|2004}}</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 worldwide 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 usually not nearly enough to affect herd immunity.  

The USA has federal vaccination recommendations according to an official CDC schedule. Requirements are up 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 usually not nearly enough to affect herd immunity.{{cn}}

As of February 2008, the CDC noted that "fewer than 100 measles cases are now reported annually in the United States and virtually all of those are linked to imported cases" in which someone is infected during overseas travel. The USA maintains herd immunity for measles, even in states where it is easy to opt out of vaccination requirements.<ref>[http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5708a3.htm]</ref> Measles can be serious; according to an article in The Times, "About one in every 15 children has complications that can include [[meningitis]], [[pneumonia]], [[fits]], [[encephalitis]] (swelling of the brain), [[blindness]] and [[brain damage]]."<ref>The Sunday Times, ''How the MMR scare led to the return of measles'', February 8, 2009 [http://www.timesonline.co.uk/tol/life_and_style/health/article5683687.ece]</ref> In the England and Wales, there were 1,348 cases of measles in 2008; two children died of the disease.<ref>The Sunday Times, ''MMR doctor Andrew Wakefield fixed data on autism'', by Brian Deer, February 8, 2009 [http://www.timesonline.co.uk/tol/life_and_style/health/article5683671.ece]</ref>

As of February 2008, the CDC noted that "fewer than 100 measles cases are now reported annually in the United States and virtually all of those are linked to imported cases" in which someone is infected during overseas travel. The USA maintains herd immunity for measles, even in states where it is easy to opt out of vaccination requirements.<ref>[http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5708a3.htm]</ref> Measles can be serious; according to an article in The Times, "About one in every 15 children has complications that can include [[meningitis]], [[pneumonia]], [[fits]], [[encephalitis]] (swelling of the brain), [[blindness]] and [[brain damage]]."<ref>The Sunday Times, ''How the MMR scare led to the return of measles'', February 8, 2009 [http://www.timesonline.co.uk/tol/life_and_style/health/article5683687.ece]</ref> In the England and Wales, there were 1,348 cases of measles in 2008; two children died of the disease.<ref>The Sunday Times, ''MMR doctor Andrew Wakefield fixed data on autism'', by Brian Deer, February 8, 2009 [http://www.timesonline.co.uk/tol/life_and_style/health/article5683671.ece]</ref>

The CDC notes that when a measles outbreak occurs, the cost to taxpayers can be substantial. Public health responsibilities include "identification of cases, isolation of patients and vaccination, administration of [[immune globulin]], and voluntary quarantine of contacts who have no evidence of measles immunity...In Iowa, the public health response to one imported measles case cost approximately $150,000."<ref>Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report, ''Outbreak of Measles --- San Diego, California, January--February 2008'', February 29, 2008 [http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5708a3.htm]</ref>

The CDC notes that when a measles outbreak occurs, the cost to taxpayers can be substantial. Public health responsibilities include "identification of cases, isolation of patients and vaccination, administration of [[immune globulin]], and voluntary quarantine of contacts who have no evidence of measles immunity...In Iowa, the public health response to one imported measles case cost approximately $150,000."<ref>Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report, ''Outbreak of Measles --- San Diego, California, January--February 2008'', February 29, 2008 [http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5708a3.htm]</ref>

Other diseases besides the measles have also started not only to reappear but also to kill babies. Hib (''[[Haemophilus influenzae]]'' type B) recently killed an infant in Minnesota by causing meningitis in the baby. The child who died had not been vaccinated. Two others who had been either partially vaccinated, but not fully protected, or had an immune deficiency were seriously sickened. The vaccine for Hib is less than twenty years old, but this is the first death due to the disease in the state of Minnesota since the vaccine was introduced.<ref>[http://children.webmd.com/vaccines/news/20090123/hib-outbreak-kills-unvaccinated-child Hib Outbreak Kills Unvaccinated Child]</ref>

Other diseases besides the measles have also started not only to reappear but also to kill children. Hib (''[[Haemophilus influenzae]]'' type B) meningitis recently killed an infant in Minnesota. The child who died had not been vaccinated. Two others who had been either partially, but not fully, vaccinated, or who had an immune deficiency were seriously sickened. The vaccine for Hib is less than twenty years old, but this is the first death due to the disease in the state of Minnesota since the vaccine was introduced.<ref>[http://children.webmd.com/vaccines/news/20090123/hib-outbreak-kills-unvaccinated-child Hib Outbreak Kills Unvaccinated Child]</ref>

===Herd Immunity in Britain===

===Herd Immunity in Britain===

Due to a decrease in vaccination, measles has become endemic in Britain. This means that measles does not need to be brought in by travelers, but instead has a large enough base of unvaccinated individuals for it to continuously spread inside the country. In London, only 71 percent of children receive the first dose of the vaccine and only 51 percent the second dose. Due to this decline, there were 461 cases in Britain in the first half of 2008. These cases have had tragic consequences, with the death of a 17 year old reported in 2008.<ref>[http://www.healthdirect.co.uk/2008/07/measles-endemic-in-britain-official.html Health Direct NHS watch blog]</ref> This immunization failure is due to parents opting out of the MMR vaccine program in the wake of the false claims concerning links between the vaccine and autism.<ref>http://www.timesonline.co.uk/tol/news/world/us_and_americas/article4100287.ece</ref>

Due to a decrease in vaccination, measles has become endemic in Britain. This means that measles does not need to be brought in by travelers, but instead has a large enough base of non-immune individuals for it to continuously spread inside the country. In London, only 71 percent of children receive the first dose of the vaccine and only 51 percent receive the second dose. Due to this decline, there were 461 measles cases in Britain in the first half of 2008. These cases have had tragic consequences, with the death of a 17 year old reported in 2008.<ref>[http://www.healthdirect.co.uk/2008/07/measles-endemic-in-britain-official.html Health Direct NHS watch blog]</ref> This immunization failure is due to parents opting out of the MMR vaccine program in the wake of the false claims that the MMR vaccine causes autism.<ref>http://www.timesonline.co.uk/tol/news/world/us_and_americas/article4100287.ece</ref>

== Adverse Reactions ==

== Adverse Reactions ==