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Background: Various recent outbreaks of hepatitis A virus (HAV) have been described in men who have sex with men despite the availability of an effective vaccine. This study aimed to determine the current rates of seroconversion after receiving HAV vaccine (HAV-V) in HIV-infected patients under real-life conditions. Setting: Patients were selected from a Southern Spanish multicentric cohort of HIV-infected subjects. Methods: Retrospective analysis of all patients who received 2 doses (standard scheme) from April 2008 to May 2016 or from June 2016 to February 2018 facing an HAV outbreak with shortage of HAV-V, 1 single dose of HAV-V. Response to HAV-V was defined as positive anti-HAV IgG between 1 and 12 months after the last vaccination dose. Results: A total of 522 patients were included, mainly men who have sex with men (86.2%). In the standard-dose group, 303/343 [88.3%; 95% confidence interval (CI): 84.5 to 91.5] patients showed seroconversion as compared with 149/179 (83.2%; 95% CI: 76.9 to 88.4) of the single-dose group (P = 0.107). Undetectable baseline HIV-RNA (adjusted odds ratio: 4.86; 95% CI: 1.86 to 12.75; P = 0.001) and a CD4+ T-cell count ≥350/μL (adjusted odds ratio, 3.96; 95% CI: 1.26 to 12.49; P = 0.019) were independently associated with response to both regimens. A higher CD4/CD8+ ratio was also associated with response after a single dose. Conclusions: HIV-infected patients should be encouraged to undergo HAV-V with 2 standard doses 6 months apart; a single dose achieves a high rate of seroconversion in those patients with favorable response factors and may be enough to limit future outbreaks in case of HAV-V shortage until supply is reestablished.

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Research on CAPTCHA has led CAPTCHA design into adopting almost exclusively graphical implementations that deal mostly with character recognition. This has reached an exhaustion point, where new approaches are vital to the survival of the technique. This paper discusses the early stages of a research that intends to solve the open problem of a CAPTCHA in the text domain offering, this way, innovative research possibilities to the CAPTCHA paradigm. It is essentially an investigation on a CAPTCHA that draws its security from the cognitive and computational aspects behind phonetic punning riddles found on Knock-Knock Jokes. By the specification of a computational model, the implementation of a prototype and its experimentation with human individuals, it is shown that the proposal is indeed feasible and that studies in non conventional areas for Information Security are the key for developing the proposed goal.