Long COVID: A Modified Delphi Consensus on Definition, Burden, Diagnosis and Management in Southeast Asia

INTRODUCTION: Long COVID is a heterogeneous post-infectious condition following acute severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. Ongoing uncertainty around its definition, burden, diagnosis and management complicates clinical recognition and care in Southeast Asia. METHODS: A modified Delphi consensus study was conducted with twelve experts from six Southeast Asian countries to develop regional guidance on long COVID. Consensus was predefined as ≥ 80% agreement, corresponding to at least 10 of 12 experts selecting the same response in multiple-choice questions or indicating agreement on Likert-scale questions (e.g. agree/strongly agree, most important/more important, relevant/highly relevant). Questions that reached consensus were removed from the subsequent round, while unresolved questions were revised, consolidated, or expanded. In the final round, a post hoc descriptive category, 'moderate endorsement', was applied to Likert-scale questions that had not reached consensus, with 'important' as the midpoint category of the five-point importance scale ('most important' to 'least important'), to capture responses judged important but falling short of the consensus threshold. RESULTS: Consensus was reached for all 'definition', 'burden' and 'management' theme questions and most 'diagnosis' questions. Experts defined long COVID as unexplained symptoms persisting for > 3 months after SARS-CoV-2 infection, distinct from post-acute COVID-19, with no minimum severity threshold requirement. Long COVID was recognised as affecting approximately 6%-10% of individuals after SARS-CoV-2 infection, consistent with published WHO and KSID estimates; clinical evaluation and symptom-guided testing were recommended for its diagnosis. Hospitalisation during acute COVID-19 was identified as a risk factor for developing long COVID. The experts recommended multidisciplinary, symptom-directed care, rehabilitation, pacing and follow-up. Vaccination and reinfection prevention were supported as important long COVID risk-reduction strategies, and early antiviral treatment should be considered to prevent severe acute illness and hospitalisation in high-risk individuals. Consensus was not reached on the past medical history required for diagnosis; moderate endorsement was observed for booster status, absence of early antiviral treatment, pre-COVID health assessment and standardised patient-reported outcome tools. CONCLUSION: This Delphi study provides a practical regional consensus framework for long COVID in Southeast Asia.