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Human papillomavirus (HPV) is a small double-stranded DNA virus that commonly infects humans. The oncogenic characteristics of HPV derive from the oncoproteins E6 and E7 that act inhibiting p53 and pRB tumor suppressors. About 5% of all cancers worldwide are attributable mainly to those known as high-risk, including HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59. Infection with HPV is common after sexual initiation, but the majority of HPV infections do not cause symptoms or disease and are cleared within 12–24 months post-infection. Only a small fraction of those infections that persist or progress to a preneoplastic lesion result in cancer. Persistence of HPV infection is needed to start the oncogenic process. Clearance of infection is common in young adults. Viral load and viral type are the main cofactors for progression from infection to cervical intraepithelial lesions and cancer. Smoking, hormonal exposure, and HIV are additional exposures that increase the risk of progression to cancer. The adverse health effects of HPV infections can be largely controlled through vaccination and screening.

Although chickenpox is usually a mild disease, it is not always free of complications, especially in adolescents and adults. Previous studies of postexposure prophylaxis conducted with experimental vaccines showed the vaccine to be highly effective if administered in the first 3 to 5 days after exposure. However, studies carried out with commercialized vaccines yielded discordant results. The aim of the present study was to assess the effectiveness of currently available varicella vaccines as postexposure prophylaxis.

ObjectiveTo evaluate, using an online non-probability sample, the beliefs about and attitudes towards cancer prevention of people professing vaccination scepticism or conspiracy theories.DesignCross sectional survey.SettingData collected mainly from ForoCoches (a well known Spanish forum) and other platforms, including Reddit (English), 4Chan (English), HispaChan (Spanish), and a Spanish language website for cancer prevention (mejorsincancer.org) from January to March 2022.ParticipantsAmong 1494 responders, 209 were unvaccinated against covid-19, 112 preferred alternative rather than conventional medicine, and 62 reported flat earth or reptilian beliefs.Main outcome measuresCancer beliefs assessed using the Cancer Awareness Measure (CAM) and Cancer Awareness Measure Mythical Causes Scale (CAM-MYCS) (both validated tools).ResultsAwareness of the actual causes of cancer was greater (median CAM score 63.6%) than that of mythical causes (41.7%). The most endorsed mythical causes of cancer were eating food containing additives or sweeteners, feeling stressed, and eating genetically modified food. Awareness of the actual and mythical causes of cancer among the unvaccinated, alternative medicine, and conspiracy groups was lower than among their counterparts. A median of 54.5% of the actual causes was accurately identified among each of the unvaccinated, alternative medicine, and conspiracy groups, and a median of 63.6% was identified in each of the three corresponding counterparts (P=0.13, 0.04, and 0.003, respectively). For mythical causes, medians of 25.0%, 16.7%, and 16.7% were accurately identified in the unvaccinated, alternative medicine, and conspiracy groups, respectively; a median of 41.7% was identified in each of the three corresponding counterparts (P<0.001 in adjusted models for all comparisons). In total, 673 (45.0%) participants agreed with the statement “It seems like everything causes cancer.” No significant differences were observed among the unvaccinated (44.0%), conspiracist (41.9%), or alternative medicine groups (35.7%), compared with their counterparts (45.2%, 45.7%, and 45.8%, respectively).ConclusionsAlmost half of the participants agreed that “It seems like everything causes cancer,” which highlights the difficulty that society encounters in differentiating actual and mythical causes owing to mass information. People who believed in conspiracies, rejected the covid-19 vaccine, or preferred alternative medicine were more likely to endorse the mythical causes of cancer than their counterparts but were less likely to endorse the actual causes of cancer. These results suggest a direct connection between digital misinformation and consequent erroneous health decisions, which may represent a further preventable fraction of cancer.