1802 painting of smallpox vaccine inventor Dr. Edward Jenner vaccinating a room full of people who then sprout cows from their bodies. The painting illustrates popular 17th century fears about vaccination. The caption reads "The Cow Pock - or - the Wonderful Effects of the New Inoculation." Source: National Library of Medicine History of Medicine Collection, "The Cow Pock - or - the Wonderful Effects of the New Inoculation," ihmj.nlm.gov (accessed Jan. 7, 2010)
The Centers for Disease Control (CDC) recommends getting 29 doses of 9 vaccines (plus a yearly flu shot after six months old) for kids aged 0 to six.  No US federal laws mandate vaccination, but all 50 states require certain vaccinations for children entering public schools. Most states offer medical and religious exemptions; and some states allow philosophical exemptions. 
Proponents say that vaccination is safe and one of the greatest health developments of the 20th century. They point out that illnesses, including rubella, diphtheria, smallpox, polio, and whooping cough, are now prevented by vaccination and millions of children’s lives are saved. They contend adverse reactions to vaccines are extremely rare.
Opponents say that children’s immune systems can deal with most infections naturally, and that injecting questionable vaccine ingredients into a child may cause side effects, including seizures, paralysis, and death. They contend that numerous studies prove that vaccines may trigger problems like autism, ADHD, and diabetes.
EARLY HISTORY OF VACCINES
The Chinese used inoculation techniques against smallpox as early as 1000 AD and similar techniques were also used in ancient Africa and Turkey.  The first instance of vaccine promotion in the United States was in 1721 when Cotton Mather, a Puritan minister, encouraged smallpox vaccination in response to an outbreak.  Vaccination as practiced today came into being when Edward Jenner, English physician and scientist, created the first smallpox vaccine using cowpox (a disease similar to smallpox that infects cows) and vaccinating an eight-year-old boy in 1796.  Jenner’s innovation was used for 200 years, with updates, and eradicated smallpox. 
In 1801 Benjamin Waterhouse, physician and co-founder and President of Harvard Medical School, began using the "Cowpox Vaccine," leading to Massachusetts becoming the first US state to promote the use of vaccination.  In 1809 the town of Milton, Massachusetts became the first US town to offer free smallpox vaccinations, which was followed by a state law that same year requiring the smallpox vaccination. 
Later, on Feb. 27, 1813, US President James Madison signed into law An Act to Encourage Vaccination, which created the National Vaccine Agency (now part of the US Department of Health & Human Services). 
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"Death the Vaccinator" published in the late 1800s by the London Society for the Abolition of Compulsory Vaccination, Source: College of Physicians of Philadelphia, "Death the Vaccinator," www.historyofvaccines.org (accessed Sep. 5, 2014)
In 1855 Massachusetts passed the first US state law mandating vaccinations for schoolchildren , followed by New York (1862), Connecticut (1872), Indiana (1881), Arkansas (1882), Illinois (1882), Virginia (1882), Wisconsin (1882), California (1888), Iowa (1889), and Pennsylvania (1895).  By 1963, 20 states would require immunization to attend public schools; and 29 states by 1970. 
In response to immunization laws, in 1878, the National Anti-Compulsory Vaccination Reporter stated that "the dangerous illnesses following the vaccine process are… on the whole… a greater evil to humanity than small-pox itself!"  The Anti-Vaccination Society of America was founded in 1879 in response to the states enacting vaccination mandates and with the belief that it "is undignified" to mandate vaccinations and that the "efficacy of vaccination as a disease preventative is a matter of individual opinion."  In 1882 the New England Anti-Compulsory Vaccination League was founded and in 1885 the Anti-Vaccination League of New York City was created.  With their influence, the anti-vaccination groups began getting vaccine mandates repealed in California, Illinois, Indiana, Minnesota, Utah, West Virginia, and Wisconsin. 
The first laboratory-created vaccine was for avian cholera (which most commonly infects chickens), developed by Louis Pasteur, French chemist and microbiologist, in 1879.  In 1885, Pasteur created the rabies vaccine, beginning an active period of vaccine development for human illnesses through the 1930s that saw vaccines developed for typhoid (1899), cholera (1911), diphtheria (1914), tuberculosis (1921), and tetanus (1924), among others.  Vaccines for polio (1955), measles (1963), mumps (1967), and rubella (1969) followed in the mid-twentieth century. 
During the active period of vaccine development, in 1901 the first Nobel Prize in Physiology or Medicine was awarded to Emil von Behring, a German physiologist, for his work developing serum therapy in connection to a diphtheria vaccination. 
On July 1, 1902, Congress passed An Act to Regulate the Sale of Viruses, Serums, Toxins, and Analogous Products (also referred to as the Biologics Control Act), which was the first legislation to control the quality of drugs, specifically the quality of vaccines. 
Later, on Feb. 20, 1905, mandatory vaccination was upheld by the US Supreme Court in Jacobson v. Massachusetts (7-2).  In the aftermath of the ruling more states across the country began to implement mandatory child vaccination as a condition of public school attendance.
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1975 World Health Organization poster promoting vaccination. Source: National Library of Medicine History of Medicine Collection, "Immunize and Protect Your Child," ihmj.nlm.gov (accessed Jan. 7, 2010)
On Nov. 13, 1922, the constitutionality of mandatory vaccination of school children was once again challenged and upheld in the Zucht v. King; the US Supreme Court declined to hear the case, stating that it was "within the police power of a state to provide for compulsory vaccination." 
In 1951, Jonas Salk, MD, and his team developed a method to cultivate the polio virus in money kidney tissue in order to be able to produce large amounts of the vaccine.  On Apr. 12, 1955 the results of the Salk vaccine trials showed the vaccine was 80-90% effective and the US government licensed the IPV polio vaccine the same day.  The vaccination program was suspended on May 8, 1955 to investigate paralysis resulting from the vaccine injection; changes to the production method were made and vaccination resumed on May 27, 1955.  The use of the Salk vaccine reduced the number of paralytic polio cases from 28,985 in 1955 to 72 in 1965.  The last case of the disease in the United States was reported in 1993, and polio was declared eliminated in the western hemisphere on Sep. 29, 1994 by the Pan American Health Organization. 
NATIONAL CHILDHOOD VACCINE INJURY ACT AND VACCINE ADVERSE EVENT REPORTING SYSTEM
In 1986 the National Childhood Vaccine Injury Act  was passed in response to a large number of lawsuits filed claiming vaccines were causing adverse reactions including brain damage and death.  The Act shielded medical professionals and vaccine manufacturers from liability if an individual suffered injury from receiving vaccines. The Act mandated that vaccine injury claims be filed with the US Court of Federal Claims rather than filed directly against physicians or vaccine manufacturers in civil court. Unlike civil court, people filing injury claims are not required to prove negligence or failure to warn; they only need to prove that a vaccine caused injury. 
On Oct. 1, 1988, the National Vaccine Injury Compensation Program (VICP) was created under the National Childhood Vaccine Injury Act.  The VICP was "established to ensure an adequate supply of vaccines, stabilize vaccine costs, and establish and maintain an accessible and efficient forum for individuals found to be injured by certain vaccines."  Between 1989 and July 1, 2014, 3,645 compensation awards have been made (amounting to over $2.7 billion in awards and $113.2 million to cover legal costs) and 9,786 claims have been dismissed (amounting to $62.8 million paid to 4,925 dismissed claimants to cover legal costs). 
Subsequently, in 1990 the CDC and FDA created the Vaccine Adverse Event Reporting System (VAERS). VAERS collects information about adverse events via reports filed by anyone, including medical professionals and family members.  VAERS receives about 30,000 reports each year.  85-90% of VAERS reports are for "mild adverse events such as fever, local reactions [such as redness at the injection site], and episodes or crying or mild irritability."  The other 10-15% of VAERS reports is for "serious adverse events involving life-threatening conditions, hospitalization, permanent disability, or death, which may or may not have been caused by a vaccine." 
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1920s school children getting diphtheria vaccination. Source: College of Physicians of Philadelphia, "1920s Vaccination," www.historyofvaccines.org (accessed Sep. 5, 2014)
In 1993 the US Congress passed the Comprehensive Childhood Immunization Act of 1993  that created the Vaccines for Children (VFC) program to provide vaccinations free of charge to children in need in order to increase the number of vaccinated children.
ANDREW WAKEFIELD AND THE AUTISM CONTROVERSY
In Feb. 1998 Lancet published an article by Andrew Wakefield, MD, titled "Ileal-Lymphoid-Nodular Hyperplasia, Non-Specific Colitis, and Pervasive Developmental Disorder in Children."  The article claimed "Rubella virus is associated with autism and the combined measles, mumps, and rubella [MMR] vaccine… has also been implicated."  Anti-vaccination groups and parents began using Wakefield’s article as rationale to opt-out of vaccinating their children.
Between 2003 and 2012, Brian Deer, an investigative reporter, examined the story and published 36 articles which accused Wakefield of "falsifying medical histories of children and essentially concocting a picture, which was the picture he was contracted to find by lawyers hoping to sue vaccine manufacturers and to create a vaccine scare."  On Mar. 3, 2004 ten of the twelve co-authors of Wakefield’s article released a "Retraction of an Interpretation" in Lancet, stating "We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism as the data were insufficient."  Lancet retracted Wakefield’s article on Feb. 2, 2010, stating "it has become clear that several elements of the 1998 paper by Wakefield et al are incorrect."  On Jan. 5, 2011, the British Journal of Medicine published an article stating that Wakefield received over $674,000 from lawyers and that, of 12 children examined, five had developmental problems before being vaccinated and three never had autism. 
As a result, on May 24, 2011, Britain stripped Wakefield of his medical license, stating Wakefield had "abused his position of trust" and "brought the medical profession into disrepute."  Wakefield contends that the investigation of his work is part of a conspiracy to "discredit and silence his research" in order to "shield the government from exposure on the vaccine scandal." 
THIMEROSAL AND AUTISM
On July 9, 1999, in response to growing concern over a link between vaccination and autism, the American Academy of Pediatrics (AAP) and the US Public Health Service (PHS) recommended that thimerosal be removed from vaccines "as soon as possible." However, they also stated, "there are no data or evidence of any harm caused by the level of exposure that some children may have encountered in following the existing immunization schedule" and that "the large risks of not vaccinating children far outweigh the unknown and probably much smaller risk, if any, of cumulative exposure to thimerosal-containing vaccines over the first 6 months of life." 
In May 2003, Representative Dan Burton (R-IN) released a report titled "Mercury in Medicine – Taking Unnecessary Risks" in which he requested that the FDA remove thimerosal from the flu vaccine and recommended independent research on the link between thimerosal in vaccines and autism. 
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1977 Star Wars vaccination promotion poster Source: US National Library of Medicine, "Parents of Earth," 1977
In 2005, Robert F. Kennedy Jr. wrote an article co-published by Salon.com (June 16) and Rolling Stone (July 14) titled "Deadly Immunity," arguing that the 2000 Simpsonwood CDC Conference was spent "discussing how to cover up the damaging data" that there were a "staggering number of earlier studies that indicate a link between thimerosal and speech delays, attention-deficit disorder, hyperactivity, and autism."  The article was corrected multiple times within days of publication, and was retracted and deleted by Salon.com and Rolling Stone on Jan. 16, 2011.  The controversy resulted in an 18-month investigation by the US Senate Committee on Health, Education, Labor and Pensions, which concluded that Kennedy's allegation was unsubstantiated and "thimerosal was [being] voluntarily removed from childhood vaccines distributed in the United States as a precaution," prompted by a joint request by the American Academy of Pediatrics and the US Public Health Service.  As of 2007, vaccines for children 6 years old and younger contain no thimerosal or only trace amounts, except for inactivated flu vaccines, which are available in both thimerosal-containing and preservative-free versions. By Nov. 30, 2009, the mercury-based preservative thimerosal had been phased out of all vaccines in the United States with the exception of certain influenza, meningococcal, and tetanus vaccines. 
On Aug. 27, 2010 the US Court of Appeals for the Federal Circuit ruled (3-0) that there is no link between vaccination and autism in the case of Cedillo v. Secretary of Health and Human Services.  The decision upheld two earlier rulings: a 2007 ruling by the United States Court of Federal Claims Office of Special Masters and an affirmation of that ruling by the Court of Federal Claims. On Feb. 22, 2011, the US Supreme Court ruled (6-2) in the case of Bruesewitz v. Wyeth  that vaccine injury claims must continue to be filed with the US Court of Federal Claims set up under the National Childhood Vaccine Injury Act of 1986, and cannot be filed directly against physicians or vaccine manufacturers in civil court.
On Aug. 25, 2011 the Institute of Medicine (IOM) issued a report, "Adverse Effects of Vaccines: Evidence and Causality."  The report brief stated that "evidence favors rejection of a causal relationship" between the Measles-Mumps-Rubella (MMR) vaccine and autism. However, it also found "evidence convincingly supports a causal relationship" between the chickenpox vaccine and chickenpox infection with subsequent pneumonia, meningitis, and hepatitis in individuals with demonstrated immune deficiencies, as well as "vaccine strain viral reactivation" (when the virus reactivates later in life) causing rare instances of encephalitis (inflammation of the brain).  The Cochrane Collaboration, in a Feb. 15, 2012 independent investigation of studies on vaccines and autism concluded, "We could assess no significant association between MMR immunisation and the following conditions: autism, asthma, leukaemia, hay fever, type 1 diabetes, gait disturbance, Chrohn's disease, demyelinating diseases, or bacterial or viral infections." A study published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on Oct. 6, 2015 found that infant rhesus macaques, whose physiology closely resembles human infants, injected with human childhood vaccines from the early 1990s (that contained thimerosal) and from 2008 (after thimerosal was phased out of childhood vaccines) exhibited no behavioral or neuropathological changes that could be linked to autism. 
POTENTIAL CONSEQUENCES FOR UNVACCINATED CHILDREN AND THEIR PARENTS
State laws in North Carolina, Ohio, and New York allow the public school system to suspend children who are not vaccinated.  Approximately 2,000 seventh- to twelfth-grade children not vaccinated against pertussis (whooping cough) were barred from attending classes in San Francisco in 2011.  On June 22, 2014, federal Judge William Kuntz upheld New York state law barring unvaccinated children from public school when other children have the chickenpox.  Many pediatricians will not treat children who have not been vaccinated.  Some legal experts believe that parents who do not vaccinate their children should be subject to criminal prosecution (including criminally negligent homicide and monetary damages) if their unvaccinated children infect and harm other children who are too young or immunocompromised to receive vaccines. 
ERADICATION AND ELIMINATION OF DISEASE
Elimination means that the disease is not present in a region, while eradication means that the disease does not exist anywhere globally. Smallpox was declared globally eradicated in 1980, the first and only disease to be eradicated thus far. Polio was declared eliminated in the United States in 1979 and in the Western Hemisphere in 1994.  Rubella was declared eliminated in the Americas on Apr. 29, 2015, and measles on Sep. 27, 2016.  The World Health Organization states that eradication and elimination is the product of vaccination programs that promote high rates of inoculation, while those opposed to vaccination state that better sanitation and clean water led to the elimination of the diseases.