Post COVID-19 usually occurs 3 months from the onset of COVID-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis. Patients report a range of disabling symptoms such as fatigue, shortness of breath, cognitive impairment, memory loss and mental health and employment issues. This clinical heterogeneity complicates the identification of the appropriate needs and care.

The aim of this cross-sectional study is to identify subgroups (clusters) of post COVID patients based on clinical symptoms, demographic characteristics, levels of fatigue and physical, cognitive and psychological functioning of the individuals.

Inclusion Criteria:

The participant must report current persisting symptoms (such as brain fog, anxiety, shortness of breath, headaches but also others) and indicate on the Post COVID-19 Functional Status Scale that these have an impact on everyday functioning (grade 2, 3, and 4). These symptoms need to be present for more than two months.

Further inclusion criteria are:

• Fatigue Severity Scale (FSS) score > 4
• Aged over 18 years old
• Willing to sign the digital informed consent
• Dutch speaking and Dutch understanding
• Be tested positive for COVID-19, i.e. by reverse transcription polymerase chain reaction (RT-PCR), computed tomography (CT) of the lungs, or symptom-based diagnosis by the general practitioner.

Exclusion Criteria:

• Pregnant women
• Pacemaker, defibrillator
• Brain or nerve disorders
• Epilepsy
• A copper spiral or recent bone fracture

Participants that match the criteria of the recently published definition of the post-COVID-19 condition will be considered eligible to participate in the study.[8] Post-COVID-19 has been defined as a condition that occurs in individuals with a history of confirmed SARS-CoV-2 infection, and that occurs usually within three months from the onset of COVID-19 with symptoms that last for at least two months and cannot be explained by an alternative diagnosis. Consequently, participants that either have or have not been hospitalized will both be allowed to participate in this study. COVID infection will be self-reported by the participant. Participants will be encouraged to show any test certificate but they are not obligated to do so.