RecruitingDevice studytVNS in Long COVID-19A prior open label study has shown that transcutaneous vagus nerve stimulation \[tVNS\] can improve the health of some patients with postacute sequelae of SARS-CoV-2 infection (PASC), severely affected enough to also fulfill criteria for myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS). The purpose of this study is to compare two sets of stimulus parameters to determine the one that best improves the health-related quality of life of these patients over a period of 6-weeks. Patients using their assigned device for at least 30 of the 42 possible opportunities will receive the best device for an additional 6-week period.