Vagus Nerve Stimulation to the Ear to Improve Symptoms in Post-COVID-19 and ME/CFS

The STIMPACT study is a single-blind, randomized, controlled crossover trial designed to evaluate the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) in alleviating fatigue and autonomic dysfunction symptoms in individuals diagnosed with Post-COVID Syndrome or Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Participants will undergo two distinct intervention phases, referred to as Intervention A and Intervention B, each lasting four weeks and separated by a washout period of at least four weeks to minimize potential carryover effects. The order of interventions will be randomized for each participant. During each intervention phase, participants will self-administer 30-minute stimulation sessions twice daily using a portable device designed for home use. Adherence to the stimulation protocol will be monitored through device usage logs and regular virtual check-ins with the research team. The primary outcome measure is the change in fatigue levels, assessed using validated instruments such as the Fatigue Severity Scale (FSS) and the Chalder Fatigue Questionnaire, alongside daily symptom tracking through electronic diaries. Secondary outcomes include assessments of quality of life (SF-36, Bell's Disability Scale), post-exertional malaise (DePaul Symptom Questionnaire - Post-Exertional Malaise subscale), autonomic function (heart rate variability metrics), sleep quality (Pittsburgh Sleep Quality Index), daytime sleepiness (Epworth Sleepiness Scale), mood (Hospital Anxiety and Depression Scale), and physical activity levels (measured via actigraphy). Data collection will occur at baseline, mid-intervention, post-intervention, and during a follow-up period, utilizing online surveys, virtual consultations, and data synchronization from wearable devices. Statistical analyses will employ mixed-model approaches to evaluate changes in outcome measures over time and between interventions, with subgroup analyses comparing responses between the Post-COVID Syndrome and ME/CFS cohorts. This study aims to provide robust evidence on the potential benefits of taVNS as a non-invasive, home-based therapeutic option for managing fatigue and autonomic dysfunction in these patient populations.