Influenza vaccines do not cause multiple sclerosis (MS). Other vaccines currently routinely recommended to the general population in the U.S.* have not been shown to cause MS.
Most studies described in the 2012 report by the Institute of Medicine (IOM), now called the National Academy of Medicine (NAM), found no association between vaccination and MS, whether assessing onset [1-5] or relapse [6, 7] in adults, or onset [1, 8] or relapse  in children; however, these studies did not provide convincing evidence due to a lack of validity and precision . Studies published since the 2012 IOM report focusing on the pandemic H1N1 influenza vaccine Pandemrix [11-13], quadrivalent HPV vaccine (Gardasil) [14-16] and hepatitis B vaccine  have also found no association with MS. A white paper on influenza vaccine safety published in 2015 concluded that while each individual study had relatively low power, as a group they provide consistent evidence against a causal association between influenza vaccine in adults and MS onset or relapse; although the data are more limited in children, there is no signal to indicate concern . A recent systematic review found no increase in risk of development of MS after vaccination against hepatitis B, HPV, influenza, MMR, tetanus, diphtheria, polio, smallpox, or BCG vaccines . Another recent literature review also found no increase in risk of onset or relapse of MS after vaccination .
Hypersensitivity reactions triggered by autoimmunity, genetics or environmental factors such as viral infection are often incriminated in the destruction of the hostís myelin basic protein (MBP) and other antigens . Similarities in features of MS and other demyelinating disorders have been described and some subjects with the diagnosis of Acute Disseminated Encephalomyelitis (ADEM) have had recurrences and progressed to MS [21, 22]. One possible mechanism is molecular mimicry, which refers to the possibility that similar epitopes shared between self-peptides and foreign peptides (introduced via infection or immunization) inadvertently cause the activation of autoreactive T or B cells, leading to autoimmunity. Of the many vaccines assessed for a possible association with MS, the hepatitis B vaccine has captured the most interest, because molecular mimicry has been demonstrated in rabbits between hepatitis B viral polymerase and the part of the MBP that leads to encephalitis . This suggests that infection with a virus showing similarities with MBP regions associated with the development of encephalitis could induce MS through molecular mimicry. However, the IOM concluded that there was no mechanistic evidence for an association between vaccination and MS, as the publications reviewed provided no evidence beyond a temporal association .
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