Impact of long COVID on diverse Australian populations: a multi-site, longitudinal prospective cohort study protocol.

BACKGROUND

Long COVID is a complex, multisystem chronic condition that may persist or fluctuate for months to years after SARS-CoV-2 infection. Despite emerging international research, significant gaps remain in understanding the full breadth of long COVID's impacts in Australia. No study has yet prospectively examined these multidimensional impacts using a culturally appropriate, user-validated toolkit. Our study aims to characterise symptom profiles, functional outcomes and psychological, social, financial and behavioural impacts of long COVID in Australian adults; identify factors associated with recovery trajectories; and validate a set of measures to support research and clinical care.

METHODS

This national, multi-site, longitudinal prospective cohort study comprises three phases: (1) survey selection and user-testing; (2) psychometric validation; and (3) a longitudinal cohort study. Survey selection was informed by literature review, Australian parliament inquiry reports and international recommendations, and refined through iterative user-testing and expert review. A total of 1000 participants aged ≥18 years from diverse cultural backgrounds with ongoing symptoms following COVID-19 infection will be divided into three cohorts based on time since infection. Surveys will be administered at seven time points over 24 months, with optional follow-up to 36 months. Data linkage to state and national health datasets will enable an objective assessment of healthcare utilisation and associated costs. Psychometric properties of the tools will be evaluated using baseline responses from the initial 300 participants, including assessments of structural/construct validity, convergent validity, known-groups validity, cross-validity, internal reliability, responsiveness and test-retest reliability. Other data analyses will include descriptive statistics, repeated-measures analysis of variance, linear mixed-effects modelling and multivariable regression models.

ETHICS AND DISSEMINATION: Ethics approval was obtained from The St Vincent's Hospital Melbourne Human Research Ethics Committee (HREC) (112108/2024/PID00364) and RMIT University HREC (28124). Research findings will be disseminated at conferences and in peer-reviewed publications.

TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12625001415493).