*1.2. Anti-Vaccination Movement*

Since their introduction, vaccinations have revolutionised health care whilst at the same time persistently facing opposition [4,5] from hesitant individuals who perceive them as unnecessary or dangerous [6]. 'Anti-vaccinators' or 'anti-vaxxers' may reject vaccinations in the belief that they contain toxins and cause serious adverse effects [7]. More extreme conspiracy theories accuse pharmaceutical companies of producing fake vaccine data, concealing harmful vaccine side effects and exaggerating vaccine efficacy statistics [8].

Hesitancy is typically associated with a lack of trust in the health-care system [9] and unfamiliarity with vaccine-preventable diseases [10]. For example, in 1974, it was reported that an antigen in the pertussis vaccine was responsible for 36 neurological complications including convulsions and intellectual developmental disorders in previously healthy children. Despite the study concluding that these complications were extremely rare and the risks of immunisation outweighed the risks of disease [9], many parents in Britain refused to vaccinate their children against pertussis throughout the 1970s and 1980s. Between 1971 and 1974, vaccination rates dropped significantly from 78.5% to 37% [11], leading to severe strain on the NHS [12,13].

The measles, mumps, and rubella (MMR) controversy was the result of a now discredited paper linking the MMR vaccine to autism in children [8,14], which led to a reduction in MMR uptake after its publication in 1998 and the debate still rumbles on. Although MMR vaccination uptake has improved since 2004, according to the WHO, it is still under the 95% threshold to ensure herd immunity; and in 2017, an estimated 142,000 people died from measles unnecessarily [6,15,16], leading the WHO to declare vaccine hesitancy as an official threat to global health in 2019 [17] and highlighting the need for medical professionals to address vaccine safety concerns to encourage uptake.
