This article explores how public health information was contested on social media during the COVID-19 pandemic. Through digital ethnography of four Finnish alternative health influencers, we examine their role in politicising and polarising health attitudes and pandemic governance, and how these dynamics evolved from the early to later stages of the crisis.

Drawing on social media content from three key periods – early pandemic (January–June 2020), late pandemic (October–December 2021), and post-pandemic (March–April 2025) – the study reveals that influencers amplified politicisation and polarisation of health and distrust in authorities by leveraging: 1) lay expertise rooted in personal pre-pandemic healing narratives, 2) alternative immunological framings, 3) explicit political opposition to public health measures, and 4) engagement with conspiracy narratives.

Influencer communication was characterised by opportunism, blending political activism, commercial interests, and personal wellness branding. By aligning with values of authenticity and trust, influencers cultivated belonging within alternative or conspiritual health communities. Yet, their trajectories varied in terms of politicisation and conspirituality, illustrating how pandemic-driven polarisation unfolded within the alternative health scene. This study offers critical insights into the evolving dynamics of the health politicisation and the role of social media in shaping public trust in medical expertise.