Our approach to the epistemology of post-truth is based on the idea that to fully comprehend any post-truth, going back to its origins (i.e., to the moment in which some faulty interpretations start to spread) can be not only relevant but illuminating.One of the most renowned cases of post-truth concerns vaccines and their alleged relationship with autism. It all started in 1998, when The Lancet published a study suggesting a link between the measles, mumps, and rubella vaccine and some symptoms (...) of autism. The case is relevant both because it is at the origins of contemporary anti-vaccinism and because it took twelve years to fully disprove what in 1998 was presented as a scientific truth: this means that the boundary between truth and falsehood has been blurred for a long period of time.For this purpose, we have applied the semiotic methodology to 20 articles from The Independent, 20 from The Telegraph, 20 from The Guardian, and 20 from The Daily Mail, published between 1998 and 2010. Unexpectedly, many elements that can be seen as ‘post-truth seeds’, such as conspiracy theories and the joint presentation of multiple truths, have been found even in the most scientifically accurate newspapers. (shrink)