Sir, – Tom Kelly argues that vaccine “scepticism” is not a fringe belief (Letters, September 5th). To support this position, he cites commentaries from senior scientific journal editors, both published more than a decade ago, on industry influence over the design and publication of drug trials, and on well-understood problems with experimental design, statistical rigour and reproducibility in biomedical research. Neither commentary makes any reference to vaccines; they are taken out of context.Plucking prestigious-sounding quotations from respected scientists and applying them to arguments they never made is not scepticism. Instead, it is a favoured, long-established science-denial tactic. Creationists use this strategy when they quote-mine the evolutionary biology literature, and climate change deniers employ it when they forensically extract and disseminate misleading text snippets from email correspondence or IPCC reports.Genuine scientific sceptics follow the evidence, wherever it brings them. Regarding vaccines, that evidence spans thousands of clinical trials, surveillance data from millions of administered doses, and objectively verifiable outcomes, such as the practical eradication and mitigation of killer diseases in humans and domestic animals. Taken together, the scientific and clinical data supporting the efficacy, safety, and benefits of vaccination are incontrovertible. Rejecting this is simply science denialism. Yours, etc, DAVID MACHUGH,Full Professor of Functional Genomics,UCD College of Health and Agricultural Sciences,University College Dublin,Dublin. Sir, – Tom Kelly encourages cynicism on the grounds that much published scientific literature may be untrue.I would like to believe him, but must be cautious as many published letters may be untrue. – Yours, etc, DR COLUM FARRELLY, FRCGP,Derry.