The COVID-19 pandemic triggered an unprecedented global health emergency that required rapid and strategic public communication. Social media—particularly Instagram—emerged as a crucial channel for public health authorities to disseminate information, engage with citizens, and promote protective behaviors. Building on this context, this study presents a comparative analysis of Instagram communication strategies adopted by public health institutions in Brazil, Portugal, and England during the COVID-19 pandemic. It examines content published between the pandemic’s onset and its official end, as declared by the World Health Organization (March 12, 2020 – May 5, 2023), and investigates an act of institutional memory observed five years later (March 2025). The content analysis was structured into three phases: the onset of the pandemic, its conclusion, and the post-pandemic period. Posts were categorized into five types: prevention information, surveillance strategies, care, health promotion, and institutional memory. By highlighting differences in visual strategies, symbolic communication, and memory practices, this study contributes to understanding the evolving role of digital platforms such as Instagram in managing public health crises. It also emphasizes the importance of communication continuity, transparency, and the symbolic value of post-crisis messaging in fostering public trust, collective memory, and the preservation of institutional visual heritage.