NCT07400848 Clinical Laboratory Evaluation, Assessment of Symptoms and Recovery in Patients With Post-COVID-19-Vaccination Syndrome
| NCT ID | NCT07400848 |
| Status | Recruiting |
| Phase | — |
| Sponsor | University of Bern |
| Condition | Post-Acute COVID-19 Vaccination Syndrome |
| Study Type | OBSERVATIONAL |
| Enrollment | 200 participants |
| Start Date | 2026-03-22 |
| Primary Completion | 2026-06-30 |
Eligibility & Interventions
Eligibility Fast-Check
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What to Expect as a Participant
This is an observational study. You will not receive an experimental treatment; researchers will collect data based on your existing condition or standard treatment.
This trial targets 200 participants in total. It began in 2026-03-22 with a primary completion date of 2026-06-30.
⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.
Brief Summary
Some people report persistent health problems after receiving the COVID-19 vaccine. These symptoms persist well beyond typical short-term vaccine side effects and are not attributable to any other known medical conditions. This condition is known as Post-Acute COVID-19 Vaccination Syndrome (PACVS). Symptoms can persist for months and affect several organ systems, causing issues such as fatigue, heart-related problems, neurological difficulties, and decreases in both physical ability and mental performance. PACVS shows similarities to Post-Acute COVID-19 syndrome (PACS) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The biological processes that cause PACVS are still not fully understood. Recent research indicates that endothelial dysfunction, abnormalities in blood coagulation, and persistent inflammatory responses may contribute significantly to this process. However, it remains unclear how symptoms develop over time, which biological markers are associated with disease severity, and how these findings could support diagnosis and future treatment strategies. The CLEAR study is an observational research project designed to address these knowledge gaps by systematically documenting symptoms over time and investigating potential biological correlates in individuals affected by PACVS. The study consists of three complementary subprojects. The PROGRESS subproject aims to assess symptom burden, disease course, and patient-reported treatment experiences over an eight-month period using standardized questionnaires completed by participants. The ENDOCLOT subproject investigates whether individuals with PACVS show objective signs of endothelial dysfunction, abnormalities in blood clotting, and markers of systemic inflammation. Endothelial function will be evaluated through non-invasive vascular reactivity tests (EndoPAT), microscopic examination of blood cells, standardized platelet function assessments, and standard laboratory diagnostics. It further explores the correlation between these biological parameters and clinical symptom trajectories identified in PROGRESS. The REAL subproject examines the role of endothelial activation and the release of inflammatory signaling molecules (cytokines) in the development and persistence of PACVS. The main hypothesis of the CLEAR study is that PACVS is associated with measurable endothelial dysfunction, inflammatory activation, and coagulation abnormalities, and that these biological changes are related to symptom severity and persistence over time. By combining longitudinal symptom assessment with biological measurements, this study aims to improve understanding of PACVS and support the development of better diagnostic and therapeutic approaches in the future.
Eligibility Criteria
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
Contact & Investigator
Mirko Schmidt, Prof. Dr.
PRINCIPAL INVESTIGATOR
Institute of Sport Science, University of Bern, Switzerland
Frequently Asked Questions
Who can join the NCT07400848 clinical trial?
This trial is open to participants of all sexes, aged 18 Years or older, studying Post-Acute COVID-19 Vaccination Syndrome. Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.
Is NCT07400848 currently recruiting?
Yes, NCT07400848 is actively recruiting participants. Contact the research team at CLEAR.ispw@unibe.ch for enrollment information.
Where is the NCT07400848 trial being conducted?
This trial is being conducted at Bern, Switzerland.
Who is sponsoring the NCT07400848 clinical trial?
NCT07400848 is sponsored by University of Bern. The principal investigator is Mirko Schmidt, Prof. Dr. at Institute of Sport Science, University of Bern, Switzerland. The trial plans to enroll 200 participants.
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