Our objective was to analyze the information in Spanish on YouTube about the influenza vaccine. In August 2020, a search was conducted on YouTube using the terms "Vacuna gripe", "Vacuna influenza", and "Vacuna gripa". Associations between the type of authorship, country of publication, and other variables (such as tone, hoaxes, and vaccination recommendations) were studied via univariate analysis. A total of 100 videos were evaluated; 57.0% were created in Mexico (24.0%), Argentina (17.0%), and Spain (16.0%), and 74.0% were produced by mass media or health professionals. Positive messages were detected in 65.0%. The main topics were the benefits of the vaccine (59.0%) and adverse effects (39.0%). Hoaxes were detected in 19 videos. User-generated content, compared to that of health professionals, showed a higher probability of hoaxes (odds ratio (OR) = 15.56), a lower positive tone (OR = 0.04), and less evidence of recommendations to vaccinate pregnant individuals (OR = 0.09) and people aged 60/65 or older. Videos published in Spain, in comparison with those from Hispanic America, presented significant differences in the positive tone of their messages (OR = 0.19) and in the evidence of the benefits of vaccination (OR = 0.32). A higher probability of hoaxes was detected in videos from Spain and the USA. Information in Spanish about the influenza vaccine on YouTube is usually not very complete. Spanish health professionals are urged to produce pro-vaccination videos that counteract hoaxes, and users in Hispanic America should be advised to consult videos produced in Hispanic American countries by health professionals to obtain reliable information.
Keywords: Spanish; YouTube; evaluation; hoaxes; influenza vaccine; information.