Abstract Purpose Guided by the Crisis and Emergency Risk Communication model (CERC, Reynolds and Seeger 2005. Crisis and emergency risk communication as an integrative model. Journal of Health Communication 10(1). 43–55.), the present study aimed to study how X (formerly Twitter) users sensemaking and efficacy based message. Additionally, the study also aimed to understand how the World Health Organization (WHO) responded to the emerging conversation. Methods Unsupervised machine learning was conducted on 6.1 million tweets between January and March 2020 to understand sensemaking about COVID-19 among X users. Additionally, content analysis was used to examine if the World Health Organization (WHO) responded to popular emerging conversations via content on their own X handle. Findings The majority of dominant topics in COVID-19 tweets from January to March 2020 related to understanding the virus and the crisis it caused. X users tried to make sense of their surroundings and re-create their familiar world by framing events. Content analysis revealed that WHO engaged in effective social listening and responded quickly to dominant X conversations to help people make sense of the situation. Practical Implications The initial stage of COVID-19 pandemic was marked with uncertainty. However, WHO had a robust communication strategy and addressed the dominant conversation during the time frame including debunking misinformation. Originality/Value The present study fills the research gap by situating the themes in the context of the health crisis and extending the CERC model to user-generated content via the lens of sensemaking and efficacy messages during the COVID-19 pandemic. Additionally, the study segmented the timelines into smaller time intervals to understand how sensemaking evolved over time.