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Sunday, July 3, 2022

Vaccine Hesitancy

 In The Politics of Autism, I analyze the discredited notion that vaccines cause autism. This bogus idea can hurt people by allowing diseases to spread  And among those diseases could be COVID-19.

Antivaxxers are sometimes violent, often abusive, and always wrong.

Heidi J. Larson, Emmanuela Gakidou, and Christopher J.L. Murray have an article in The New England Journal of Medicine titled "The Vaccine-Hesitant Moment."

Although many observers point to the 1998 Lancet article by Wakefield et al. (retracted in 2010) as the source of parental fears that MMR vaccination might cause autism, the search for what could be causing the seeming increase in autism was already brewing. In the United States, however, anxieties were more focused on thimerosal in vaccines as a possible cause of autism.45 The attention to thimerosal emerged in the context of a larger global movement that highlighted concern about mercury in food and drugs and in the environment. In 1999, as part of a review of mercury-related ingredients in all food and drugs, the Food and Drug Administration called for an assessment of thimerosal in childhood vaccines, although the small amount of thimerosal used in vaccines contains only a minute amount of ethylmercury and does not contain any methylmercury (the more dangerous type of mercury), which was the prime focus of the larger review.46 The U.S. Public Health Service and the American Academy of Pediatrics followed with a recommendation to remove thimerosal from childhood vaccines as a precautionary measure.47 Even though the recommendation was precautionary, with no evidence of harm, it reinforced public concern and prompted an initial 38% decrease in the hospitals that offered hepatitis B vaccination with thimerosal-containing vaccines for infants.48
To address the growing concerns, the Institute of Medicine conducted a major review of studies investigating links between vaccines and autism and concluded that neither MMR vaccines (which do not contain thimerosal) nor thimerosal-containing vaccines could cause autism.49 Meanwhile, some attention was shifted to the possibility that the increased number of vaccines given to children could be a cause of autism, a concern that is also not supported by any evidence. Nonetheless, the parental concerns have persisted. One study showed 70 additional MMR vaccine–related injury claims per month in the United States after publication of the report by Wakefield et al.50 Other research pointed to the effect of concern about a link between the MMR vaccine and autism on vaccine hesitancy in Somali immigrant communities in Norway and the United States.51 In 2012, a court ruling in Italy granted compensation for vaccine-related injury on the basis of the report by Wakefield and colleagues, which further amplified public anxiety. Having lost his credentials as a general practitioner in the United Kingdom, Wakefield became an activist, appealing to concerned parents and reinforcing their vaccine anxieties, alongside environmental lawyer turned vaccine critic Robert F. Kennedy, Jr., whose previous work on the toxic effects of mercury in the environment provided fertile ground for his campaign against thimerosal and vaccine safety risks more broadly. The launch of Google in 1998, followed by a cascade of new Internet-based and social media technologies, allowed widespread access to information, as well as misinformation, and fueled the viral spread of questioning about vaccines (Figure 1).52
A study in Italy investigated YouTube video content between 2007 and 2017 that focused on the suspected link between the MMR vaccine and autism.53,54 In addition to an escalation in the amount of negative content over the 10-year study period, partly reflecting the growth of YouTube after its 2005 launch, the study showed that negative videos about the MMR vaccine outnumbered positive ones by a factor of 3, with the negative videos more widely viewed. Another Italian study of vaccine-related content on YouTube had similar findings. A number of studies investigating HPV vaccine content on YouTube also showed that negative videos attracted a larger following than positive ones.55-57

Concern about one vaccine can also prompt questioning and hesitancy regarding other vaccines, such as the reported risks associated with a dengue vaccine (Dengvaxia) in the Philippines that contributed to a drop in measles vaccination58 and an HPV vaccine scare in Denmark that triggered a decline in MMR vaccine uptake. After HPV vaccine uptake declined (from 95% to just over 30%) after negative media reports, two-dose MMR vaccine coverage also dropped, from 86% to 80% among girls and from 85% to 79% among boys.59