Blood markers and vascular function testing for people with persistent symptoms after COVID-19 vaccination

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This observational effort follows adults with self-reported persistent symptoms after COVID-19 vaccination and matched healthy controls to map symptom trajectories and biological measures. Participants provide blood samples for analysis of coagulation, endothelial, and inflammatory markers and undergo non-invasive EndoPAT testing to measure reactive hyperemia index. The PROGRESS arm includes an eight-month follow-up while ENDOCLOT and REAL include more detailed laboratory and matched-control comparisons. Results will be used to link biological signatures to symptom patterns and recovery over time.

Why it matters

Who can join: the full rules

General Criteria (apply to all study parts: PROGRESS, ENDOCLOT, REAL, patients and matched healthy controls)

Inclusion Criteria

1. Age ≥ 18 years
2. Sufficient knowledge of German to complete study-related questionnaires and procedures

Exclusion Criteria

1. Severe cognitive, physical impairment or psychiatric conditions impeding participation
2. Active oncological disease or immunosuppressive
3. Known pregnancy at the time of enrolment

PROGRESS (patients only)

Inclusion Criteria

1. Coded participation with online consent confirmation
2. Self-reported onset of persistent symptoms temporally associated with a COVID-19 vaccination
3. Willingness and ability to participate in the 8-month follow-up period

Exclusion Criteria

1\. No specific exclusion criteria for this part

ENDOCLOT and REAL (patients and matched healthy controls)

Inclusion Criteria

1. Signed informed consent form
2. For patients:

   1. Receipt of at least one COVID-19 vaccination
   2. Onset of new, otherwise unexplained symptoms within 0-14 days after vaccination
   3. Persistence of symptoms for at least 6 months following vaccination
   4. Selection is based on a diagnosis of ME/CFS according to the Canadian Consensus Criteria (CCC) and PEM.

2\. For controls: History of COVID-19 vaccination without persistent adverse effects; age (+/- 10 years), and sex match to a corresponding case

Exclusion Criteria (patients and matched healthy controls)

1. Clinically suspected or laboratory confirmed SARS-CoV-2 infection after vaccination or temporally related to symptom onset.
2. Concurrent pre-existing Long COVID symptoms, obtained from the patient´s history
3. Any self-reported or uncertain history of an acute infectious event (including mild or subclinical infections) in temporal proximity to COVID-19 vaccination
4. Known pre-existing medical conditions or ongoing medications that could plausibly explain the reported symptoms (e.g., preexisting ME/CFS, POTS, fibromyalgia, small-fiberneuropathy, autoimmune disease with systemic involvement or other chronic multisystemic dysautonomia syndromes)
5. Use of long-term, high-dose anti-inflammatory

Where it's running

• Institute of Sport Science, University of Bern
  Bern, Switzerland Recruiting

Study contacts

• Principal investigator: Mirko Schmidt, Prof. Dr. — Institute of Sport Science, University of Bern, Switzerland
• Study coordinator: Mirko Schmidt, Prof. Dr.
• Email: CLEAR.ispw@unibe.ch
• Phone: +41 79 342 67 30

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.