Editing Vaccination (section)

=== Ingredients ===
The ingredients of vaccines can vary greatly from one to the next and no two vaccines are the same. The CDC has compiled a list of vaccines and their ingredients that is readily accessible on their website.<ref>{{Cite web|url=https://www.cdc.gov/vaccines/vac-gen/additives.htm|title=Vaccines: Vac-Gen/Additives in Vaccines Fact Sheet|date=12 July 2018|website=U.S. [[Centers for Disease Control and Prevention]] (CDC)|access-date=15 March 2019|archive-date=30 May 2019|archive-url=https://web.archive.org/web/20190530215608/https://www.cdc.gov/vaccines/vac-gen/additives.htm|url-status=live}}</ref>

==== Aluminium ====
[[Aluminium]] is an adjuvant ingredient in some vaccines. An adjuvant is a type of ingredient that is used to help the body's immune system create a stronger immune response after receiving the vaccination.<ref name="AdjuvantsUSCDC-2019a">{{Cite web|url=https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html|title=Adjuvants help vaccines work better. Vaccine Safety CDC|date=23 January 2019|website=U.S. [[Centers for Disease Control and Prevention]] (CDC)|access-date=15 March 2019|archive-date=15 March 2019|archive-url=https://web.archive.org/web/20190315224921/https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html|url-status=live}}</ref> Aluminium is in a [[Salt (chemistry)|salt]] form (the ionic version of an element) and is used in the following compounds: [[aluminium hydroxide]], [[aluminium phosphate]], and [[aluminium potassium sulfate]]. For a given element, the [[ion]] form has different properties from the elemental form. Although it is possible to have [[Aluminium toxicity in people on dialysis|aluminium toxicity]], [[aluminium salt]]s have been used effectively and safely since the 1930s when they were first used with the [[diphtheria]] and [[tetanus]] vaccines.<ref name="AdjuvantsUSCDC-2019a" /> Although there is a small increase in the chance of having a local reaction to a vaccine with an aluminium salt (redness, soreness, and swelling), there is no increased risk of any serious reactions.<ref>{{cite journal | vauthors = Jefferson T, Rudin M, Di Pietrantonj C | title = Adverse events after immunisation with aluminium-containing DTP vaccines: systematic review of the evidence | journal = The Lancet. Infectious Diseases | volume = 4 | issue = 2 | pages = 84–90 | date = February 2004 | pmid = 14871632 | doi = 10.1016/S1473-3099(04)00927-2 }}</ref><ref>{{cite journal | vauthors = Mitkus RJ, King DB, Hess MA, Forshee RA, Walderhaug MO | title = Updated aluminum pharmacokinetics following infant exposures through diet and vaccination | journal = Vaccine | volume = 29 | issue = 51 | pages = 9538–43 | date = November 2011 | pmid = 22001122 | doi = 10.1016/j.vaccine.2011.09.124 | doi-access = free }}</ref>

==== Mercury ====
Certain vaccines once contained a compound called [[thiomersal]] or thimerosal, which is an [[organic compound]] containing [[Mercury (element)|mercury]]. [[Organomercury]] is commonly found in two forms. The [[methylmercury]] cation (with one carbon atom) is found in mercury-contaminated fish and is the form that people might ingest in mercury-polluted areas ([[Minamata disease]]), whereas the [[ethylmercury]] cation (with two carbon atoms) is present in thimerosal, linked to [[thiosalicylic acid|thiosalicylate]].<ref name="ThimerosalUSCDC-2019b">{{Cite web|url=https://www.cdc.gov/vaccinesafety/concerns/thimerosal/index.html|title=Thimerosal in Vaccines Thimerosal Concerns Vaccine Safety CDC|date=24 January 2019|website=U.S. [[Centers for Disease Control and Prevention]] (CDC)|access-date=22 March 2019|archive-date=17 August 2011|archive-url=https://web.archive.org/web/20110817063316/http://www.cdc.gov/vaccinesafety/concerns/thimerosal/index.html|url-status=live}}</ref> Although both are organomercury compounds, they do not have the same chemical properties and interact with the human body differently. Ethylmercury is cleared from the body faster than methylmercury and is less likely to cause toxic effects.<ref name="ThimerosalUSCDC-2019b" />

Thimerosal was used as a [[preservative]] to prevent the growth of [[bacteria]] and [[Fungus|fungi]] in vials that contain more than one dose of a vaccine.<ref name="ThimerosalUSCDC-2019b" /> This helps reduce the risk of potential [[infection]]s or serious illness that could occur from [[contamination]] of a vaccine vial. Although there was a small increase in risk of injection site redness and swelling with vaccines containing thimerosal, there was no increased risk of serious harm or [[autism]].<ref>{{cite journal | vauthors = Ball LK, Ball R, Pratt RD | title = An assessment of thimerosal use in childhood vaccines | journal = Pediatrics | volume = 107 | issue = 5 | pages = 1147–54 | date = May 2001 | pmid = 11331700 | doi = 10.1542/peds.107.5.1147 }}</ref><ref>{{Cite web|url=https://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/UCM096228#bib|title=Vaccine Safety & Availability - Thimerosal and Vaccines|website=www.fda.gov|access-date=22 March 2019|archive-date=6 January 2013|archive-url=https://web.archive.org/web/20130106215029/https://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/UCM096228#bib|url-status=live}}</ref> Even though evidence supports the safety and efficacy of thimerosal in vaccines, thimerosal was removed from childhood vaccines in the United States in 2001 as a precaution.<ref name="ThimerosalUSCDC-2019b" />