Patients start on day 0, when the first assessment takes place. This consists of a
medical diagnostic interview and sociodemographic, anthropometric, medical and functional
data are collected (for a detailed description, see chapter 5. Statistics). Subsequently,
the patients fill out the given questionnaires (paper/pencil version), which are then
evaluated. Subsequently, the test persons are trained by a doctor how the electrical
stimulation works with a demo device. Finally, the device is taken over by the company
Schwa-Medico. The whole first assessment lasts about 2 hours and always takes place from
8 a.m. at constant room temperature (22-23 C°).

The outcome parameters are recorded before the start of the vagus nerve stimulation (T0),
during the treatment after 4 weeks (T0+4Wo) and after a total of 12 weeks (T0+12Wo) after
the end of the therapy. Which assessments are collected at the different time points is
listed in the biometry section. The assessments are performed by physicians of the
Department of Physical Medicine, Rehabilitation and Occupational Medicine. All
assessments take place at relatively the same time, at constant room temperature (22-23
C°). The patients have to appear fasting.

T0: Medical history, examination, randomization, pre-tests, enrollment. T0+4Wo:
Intermediate examination T0+12Wo: final examination, post-tests, return of device

This pilot study investigates the acceptability, feasibility, and implementation of the
VNS measure in Long COVID patients. In addition, effects on autonomic nervous system
parameters (heart rate, blood pressure, rate pressure product, heart rate variability =
HRV, cortisol in saliva), on symptoms fatigue, dyspnea as well as health-related quality
of life (HRQOL) are described:

Time points: T0, T0+4wk, T0+12wk.

Parameters - collected at relatively the same time each day, at constant room temperature
(22-23 C°):

- Documentation of blood pressure and pulse rate: by means of Boso Medicus (Bosch +
Sohn GmbH u. Co. KG, Jungingen, Germany), calculation of the so-called "rate
pressure-product" (syst. blood pressure x heart rate)

- Heart rate variability

- Salivary cortisol

- Fatigue: Brief Fatigue Inventory (BFI)

- Health-related quality of life (HRQOL): SF-36 (short form) questionnaire instrument

- Dyspnea: Modified Borg Scale

- Sleep: Insomnia Severity Index (ISI)