Face masks on Instagram: an analysis of public health authorities' guidance toward prevention.

Instagram (IG) has been used as a health promotion tool by national and international sanitary authorities to tackle COVID-19. The profile of the World Health Organization (WHO) on IG contributed to spread and update information on the new coronavirus prevention This study focus attention on a non-pharmaceutical control measure (face mask in the community) and discusses the adaptation of health authorities from Portugal and Brazil to WHO guidelines on this topic, and how they passed them to citizens. A content analysis of posts from WHO, Portuguese National Health Service (NHS), and the Brazilian Ministry of Health (MH) profiles on IG was carried out, in the first 100 days of the pandemic. The sample is composed of 65 posts - WHO (12), NHS (36) and, MH (17). NHS highlights masks in 8,8% of posts and MH in 3,3%. WHO guidelines followed scientific evidence and prioritized the surgical masks, while NHS and MH adapted the guidelines to regional scenarios (community transmission and difficulty to social distancing) and produced information on non-surgical masks. NHS recommends the use of certified non-surgical masks. MH diverged from WHO guidelines and advised cloth masks. NHS has adopted the preventive approach and the use of celebrities to stress the importance of following its guidelines. MH adopted an institutional approach to encourage adherence to the instructions. Both profiles offered incomplete content on the production, use, disposal, and maintenance of masks.