This article traces the origin, sustenance and implications of a persistent rumour that is responsible for low measles mumps and rubella (MMR) vaccination uptake in the Somali diaspora in a number of countries across the globe. The rumour stipulates that the MMR vaccine - the silent shot - causes autism spectrum disorder (ASD). Although the association between MMR and ASD is non-causal, and various public health initiatives have promoted health information campaigns, the rumour continues to circulate in the Somali diaspora in many countries, including Sweden. This paper shows that there are valid reasons for this. The findings from this paper draw on a systematic scoping review and qualitative interview data from Sweden. The results show that the Somali community experiences higher than average rates of ASD compared to the general population. Moreover, ASD does not exist in the Somali language or their home country, is considered a Western disease that only affects Somali children in the diaspora, and is a highly stigmatised disease. Also, the Somali diaspora has had negative experiences with ASD diagnosis and care. The rumour has been sustained by the absence of an answer to their ASD fear and through active diaspora networks on social media. The network that surrounds the rumour has arguably further helped to create an epistemic community for a community whose concerns have been silenced.
Keywords: ASD; MMR; Somali diaspora; Sweden; Vaccine confidence; rumours.