Sweden's public health response to COVID-19: a qualitative study building on a realist approach.

BACKGROUND: Sweden's healthcare system, known for its equity and efficiency, faced criticism in the early months of the COVID-19 pandemic due to its high mortality rate compared to other Nordic countries. This study aims to explore the Swedish public health system's response to emerging respiratory infectious diseases, particularly COVID-19, using a realist approach. It analyzes contextual factors, interventions, mechanisms, and outcomes to provide a comprehensive understanding of the response, including debates around voluntary versus mandatory measures and the protection of vulnerable groups such as older adults. OBJECTIVE: To explore how and why Sweden's socio-political and healthcare context influenced the interventions employed and their acceptability at both individual and collective levels. METHODS: A realist approach was employed, combining qualitative data from semi-structured interviews with 11 public health experts, including researchers and infectious disease specialists. Data were analyzed using both deductive and inductive approaches and interpreted through the Context-Intervention-Mechanism-Outcome (CIMO) framework. RESULTS: Key contextual factors included high trust in authorities, political decentralization, and the structure of the healthcare system. Notable interventions involved targeted vaccination campaigns, recruitment of retired healthcare workers, and increased digitalization. Mechanisms driving outcomes included trust, acceptance, and stakeholder engagement, which facilitated adaptation and acceptability of interventions. Interviewees highlighted challenges related to the timing and adequacy of measures, particularly for older adults in long-term care. CONCLUSION: While Sweden's public health response was effective in several areas, it faced challenges due to decentralization, voluntary non-pharmaceutical interventions, and workforce burnout. The realist approach highlights the importance of context-sensitive mechanisms such as trust and cooperation, and the need for stronger coordination and tailored strategies for vulnerable populations. These findings provide valuable insights for strengthening public health systems and pandemic preparedness globally.