Post-Acute COVID-19 Vaccination SyndromeCLEARNCT07400848
Clinical Laboratory Evaluation, Assessment of Symptoms and Recovery in Patients With Post-COVID-19-Vaccination Syndrome
An observational study of Post-Acute COVID-19 Vaccination Syndrome and Postviral Fatigue, run by University of Bern at 1 site in Switzerland.
Trial 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). Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Post-Acute COVID-19 Vaccination Syndrome, Postviral Fatigue
- What is being tested?
- Blood sampling and analysis and The continuous Reactive Hyperemia Index (InRHI) measured by EndoPAT
- How many people
- 200 participants
- Where
- 1 siteSwitzerland
- Study dates
- 22 Mar 2026to 15 Nov 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Progress:The study aims to enrol approximately 150-200 adults (≥18 years) who report persistent and severe symptoms following COVID-19 vaccination. Endoclot/Real: The study includes 40 individuals with suspected PACVS who meet criteria for ME/CFS and PEM, as identified through the PROGRESS subproject. Each patient is matched with a healthy control of similar age (±10 years) and sex. Control participants must have received a COVID-19 vaccination but report no persistent adverse effects and no chronic illness.
Who may be able to join
- Age ≥ 18 years
- Sufficient knowledge of German to complete study-related questionnaires and procedures
- Coded participation with online consent confirmation
- Self-reported onset of persistent symptoms temporally associated with a COVID-19 vaccination
- Willingness and ability to participate in the 8-month follow-up period
- Signed informed consent form
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- For patients:
- Receipt of at least one COVID-19 vaccination
- Onset of new, otherwise unexplained symptoms within 0-14 days after vaccination
- Persistence of symptoms for at least 6 months following vaccination
- 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
Who cannot join
- Severe cognitive, physical impairment or psychiatric conditions impeding participation
- Active oncological disease or immunosuppressive
- Known pregnancy at the time of enrolment
- PROGRESS (patients only)
- 1. No specific exclusion criteria for this part
- ENDOCLOT and REAL (patients and matched healthy controls)
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- Clinically suspected or laboratory confirmed SARS-CoV-2 infection after vaccination or temporally related to symptom onset.
- Concurrent pre-existing Long COVID symptoms, obtained from the patient´s history
- Any self-reported or uncertain history of an acute infectious event (including mild or subclinical infections) in temporal proximity to COVID-19 vaccination
- 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)
- Use of long-term, high-dose anti-inflammatory
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site, 1 recruiting
- Recruiting
Institute of Sport Science, University of Bern
Bern, 3012
Michaela Fux, PD Dr. phil. nat., CLEAR.ispw@unibe.ch
About this study
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.
Read more
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.
- Being tested
- Blood sampling and analysis, The continuous Reactive Hyperemia Index (InRHI) measured by EndoPAT
- Keywords
- Vaccine-Related Adverse Event, Endothelial Dysfunction, Coagulation Abnormalities, Inflammation, Cytokines, Patient-Reported Outcomes, Symptom Burden, Disease Trajectory, Reactive Hyperemia Index
- Medical subject headings
- Fatigue Syndrome, Chronic, Inflammation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Blood sampling and analysisDiagnostic test
Blood sampling to analyze:
- Routine laboratory diagnostics including complete blood count, coagulation and inflammation markers (e.g., fibrinogen, von Willebrand Factor, D-dimer, Factor VIII, hsCRP, Troponin-T, NT-proBNP
- Platelet function analysis using the Multiplate Analyzer (ADPtest, ASPItest, TRAPtest)
- Blood morphology assessment using real-time confocal microscopy
- Endothelial activation (Syndecan-1, ICAM-1, PAI-1/tPA complex, Heparan sulfate)
- Complement activation (sC5b-9)
The continuous Reactive Hyperemia Index (InRHI) measured by EndoPATOther
To assess endothelial function, participants undergo a non-invasive measurement using the EndoPAT device. This system evaluates vascular reactivity by continuously recording the peripheral arterial tone (PAT) signal via pneumatic finger probes placed on both index fingers. The total duration of the measurement is approximately 17 minutes. During the first 6 minutes, the baseline vascular tone is recorded at rest. This is followed by a 5-minute arterial occlusion phase, during which a blood pressure cuff on one arm (typically the non-dominant arm) is inflated to suprasystolic pressure to temporarily interrupt arterial blood flow. After the cuff is released, the reactive hyperemia response is recorded for an additional 6 minutes to assess endothelial-dependent vasodilation. The procedure is painless and well-tolerated. Participants may experience a mild tingling sensation in the occluded arm during the occlusion phase. No adverse effects are expected.
| Study group | Role | What they receive |
|---|---|---|
| Post-Acute COVID-19 Vaccination Syndrome Patients | Not described Receives: Diagnostic Test: Blood sampling and analysis; Other: The continuous Reactive Hyperemia Index (InRHI) measured by EndoPAT | |
| Healthy controls | Matched (similar age (±10 years) and sex) Receives: Diagnostic Test: Blood sampling and analysis; Other: The continuous Reactive Hyperemia Index (InRHI) measured by EndoPAT |
What is being measured
The primary outcome is the main question the study is designed to answer.
Self-reported health status (EQ-VAS)
Self-reported overall health status measured using the EuroQoL Visual Analogue Scale (EQ-VAS), ranging from 0 to 100, with higher scores indicating better perceived health status.
Measured: From enrollment to baseline assessment (T0)
Health-related quality of life (EQ-5D-5L index score)
Health-related quality of life assessed using the EuroQoL EQ-5D-5L index score, typically ranging from values below 0 (health states worse than death) to 1, with higher scores indicating better health-related quality of life.
Measured: From enrollment to baseline assessment T0
Reactive Hyperemia Index (lnRHI)
Continuous Reactive Hyperemia Index measured using EndoPAT; noting that values ≤0.51 indicating dysfunction
Measured: From enrollment to the day of examination, estimated to occur within 14 days after enrollment.
Secondary outcomes (24)
Change in self-reported health status (EQ-VAS)
Self-reported health status measured using the EQ-VAS, ranging from 0 to 100, with higher scores indicating better perceived health status.
Measured: During follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks; T2) after enrollment.
Change in health-related quality of life (EQ-5D-5L index score)
Health-related quality of life measured using the EQ-5D-5L index score; higher scores indicate better quality of life.
Measured: During follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Functional impairment (Bell Disability Scale)
Functional impairment assessed using the Bell Disability Scale, ranging from 0 to 100, with lower scores indicating greater disability.
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
ME/CFS symptom severity (Canadian Consensus Criteria)
Assessment of ME/CFS symptom severity, including fatigue, post-exertional malaise, unrefreshing sleep, pain, cognitive/neurological impairments, and autonomic, neuroendocrine, or immune manifestations. Symptoms are rated on a standardized scale, with higher scores indicating greater symptom severity and functional impairment.
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Presence of post-exertional malaise (PEM)
Presence of post-exertional malaise assessed using a standardized PEM screening instrument (binary outcome: present/absent whereby at least one of the answer is indicated with a frequency and severity of ≥ 2. )
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Functional capacity (FUNCAP55)
Functional capacity assessed using the FUNCAP55 screening instrument; higher scores indicate better functional capacity.
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Reported treatments and medications
Self-reported past and current treatments and medications used by participants.
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Self-reported treatment effects and side effects
Participant-reported perceived treatment effects and adverse effects.
Measured: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Platelet reactivity (ADPtest AUC)
Platelet aggregation measured using Multiplate analyzer (ADPtest), reported as area under the curve (AUC); higher values indicate increased platelet reactivity.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Platelet reactivity (ASPItest AUC)
Platelet aggregation measured using Multiplate analyzer (ASPItest), reported as area under the curve (AUC); higher values indicate increased platelet reactivity.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Platelet reactivity (TRAPtest AUC)
Platelet aggregation measured using Multiplate analyzer (TRAPtest), reported as area under the curve (AUC); higher values indicate increased platelet reactivity.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
High-sensitivity C-reactive protein (hs-CRP) level
Serum hs-CRP concentration; higher levels indicate increased systemic inflammation
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Fibrinogen level
Plasma fibrinogen concentration; higher levels indicate increased coagulation activity
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
D-dimer level
Plasma D-dimer concentration; higher levels indicate increased fibrin turnover
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
von Willebrand factor level
Plasma von Willebrand factor concentration; higher levels indicate endothelial activation.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Factor VIII activity
Plasma Factor VIII activity; higher activity indicates increased coagulation potential.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Troponin T (high sensitivity)
High-sensitivity cardiac troponin T concentration; higher levels indicate myocardial injury.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
NT-proBNP level
Plasma NT-proBNP concentration; higher levels indicate cardiac strain.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Blood cell morphology
Microscopic assessment of leukocyte count and platelet and erythrocyte morphology.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Syndecan-1 level
Plasma Syndecan-1 concentration; higher levels indicate increased endothelial activation.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
ICAM-1 level
Plasma ICAM-1 concentration; higher levels indicate endothelial activation.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
PAI-1/tPA complex level
Plasma PAI-1/tPA complex concentration; higher levels indicate impaired fibrinolysis.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Heparan sulfate level
Plasma heparan sulfate concentration; higher levels indicate glycocalyx degradation.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Terminal complement complex (sC5b-9) level
Plasma sC5b-9 concentration; higher levels indicate complement activation.
Measured: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Feb 2026
- Study start22 Mar 2026
- Primary completion30 Jun 2026 (estimated)
- Study completion15 Nov 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Post-Acute COVID-19 Vaccination SyndromeStudies of the same condition, open and under way.
- More trials run by University of BernThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Other
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Bern
- Sponsor type
- University, hospital or other
- Collaborators
- private practice Cell-Re-Active-Training in Bern, Post-Vakzin-Syndrom Schweiz, Medical University Innsbruck
- Responsible party
- Sponsor
- Investigators
- Mirko Schmidt, Prof. Dr., Principal investigator, Institute of Sport Science, University of Bern, SwitzerlandDieter Thommen, Dr.med., Principal investigator, Praxis für Cell-Re-Active-Training, Bern, Switzerland
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07400848
- Sponsor's protocol ID
- 2025-01382
- Other IDs
- 2025
- Acronym
- CLEAR
- Status last verified
- May 2026
- First submitted
- 3 Feb 2026
- Last updated
- 5 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Clinical Laboratory Evaluation, Assessment of Symptoms and Recovery in Patients With Post-COVID-19-Vaccination Syndrome
- ClinicalTrials.gov ID
- NCT07400848
- Acronym / sponsor ID
- CLEAR / 2025-01382
- Keywords
- Vaccine-Related Adverse Event, Endothelial Dysfunction, Coagulation Abnormalities, Inflammation, Cytokines, Patient-Reported Outcomes, Symptom Burden, Disease Trajectory
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- University of BernUniversity, hospital or other
- Collaborators
- private practice Cell-Re-Active-Training in Bern, Post-Vakzin-Syndrom Schweiz, Medical University Innsbruck
- Study start
- 22 Mar 2026 (actual)
- Primary completion
- 30 Jun 2026 (estimated)
- Study completion
- 15 Nov 2026 (estimated)
- First posted
- 10 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Observational model
- Case-control
- Time perspective
- Other
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Post-Acute COVID-19 Vaccination Syndrome Patients | – | Diagnostic Test: Blood sampling and analysis, Other: The continuous Reactive Hyperemia Index (InRHI) measured by EndoPAT |
| Healthy controls | – | Diagnostic Test: Blood sampling and analysis, Other: The continuous Reactive Hyperemia Index (InRHI) measured by EndoPATMatched (similar age (±10 years) and sex) |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Progress:The study aims to enrol approximately 150-200 adults (≥18 years) who report persistent and severe symptoms following COVID-19 vaccination. Endoclot/Real: The study includes 40 individuals with suspected PACVS who meet criteria for ME/CFS and PEM, as identified through the PROGRESS subproject. Each patient is matched with a healthy control of similar age (±10 years) and sex. Control participants must have received a COVID-19 vaccination but report no persistent adverse effects and no chronic illness.
Key inclusion criteria (12 listed)
- Age ≥ 18 years
- Sufficient knowledge of German to complete study-related questionnaires and procedures
- Coded participation with online consent confirmation
- Self-reported onset of persistent symptoms temporally associated with a COVID-19 vaccination
- Willingness and ability to participate in the 8-month follow-up period
Key exclusion criteria (11 listed)
- Severe cognitive, physical impairment or psychiatric conditions impeding participation
- Active oncological disease or immunosuppressive
- Known pregnancy at the time of enrolment
- PROGRESS (patients only)
- 1. No specific exclusion criteria for this part
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Blood sampling and analysisBlood sampling to analyze: 1. Routine laboratory diagnostics including complete blood count, coagulation and inflammation markers (e.g., fibrinogen, von Willebrand Factor, D-dimer, Factor VIII, hsCRP, Troponin-T, NT-proBNP 2. Platelet function analysis using the Multiplate Analyzer (ADPtest, ASPItest, TRAPtest) 3. Blood morphology assessment using real-time confocal microscopy 4. Endothelial activation (Syndecan-1, ICAM-1, PAI-1/tPA complex, Heparan sulfate) 5. Complement activation (sC5b-9) | Diagnostic test | Healthy controls, Post-Acute COVID-19 Vaccination Syndrome Patients |
| The continuous Reactive Hyperemia Index (InRHI) measured by EndoPATTo assess endothelial function, participants undergo a non-invasive measurement using the EndoPAT device. This system evaluates vascular reactivity by continuously recording the peripheral arterial tone (PAT) signal via pneumatic finger probes placed on both index fingers. The total duration of the measurement is approximately 17 minutes. During the first 6 minutes, the baseline vascular tone is recorded at rest. This is followed by a 5-minute arterial occlusion phase, during which a blood pressure cuff on one arm (typically the non-dominant arm) is inflated to suprasystolic pressure to temporarily interrupt arterial blood flow. After the cuff is released, the reactive hyperemia response is recorded for an additional 6 minutes to assess endothelial-dependent vasodilation. The procedure is painless and well-tolerated. Participants may experience a mild tingling sensation in the occluded arm during the occlusion phase. No adverse effects are expected. | Other | Healthy controls, Post-Acute COVID-19 Vaccination Syndrome Patients |
Primary outcome
Self-reported health status (EQ-VAS)
Time frame: From enrollment to baseline assessment (T0)
Self-reported overall health status measured using the EuroQoL Visual Analogue Scale (EQ-VAS), ranging from 0 to 100, with higher scores indicating better perceived health status.
Health-related quality of life (EQ-5D-5L index score)
Time frame: From enrollment to baseline assessment T0
Health-related quality of life assessed using the EuroQoL EQ-5D-5L index score, typically ranging from values below 0 (health states worse than death) to 1, with higher scores indicating better health-related quality of life.
Reactive Hyperemia Index (lnRHI)
Time frame: From enrollment to the day of examination, estimated to occur within 14 days after enrollment.
Continuous Reactive Hyperemia Index measured using EndoPAT; noting that values ≤0.51 indicating dysfunction
24 secondary outcomes
Change in self-reported health status (EQ-VAS)
Time frame: During follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks; T2) after enrollment.
Change in health-related quality of life (EQ-5D-5L index score)
Time frame: During follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Functional impairment (Bell Disability Scale)
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
ME/CFS symptom severity (Canadian Consensus Criteria)
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Presence of post-exertional malaise (PEM)
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Functional capacity (FUNCAP55)
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Reported treatments and medications
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Self-reported treatment effects and side effects
Time frame: From enrollment to baseline assessment (T0), and during follow-up at approximately 4 months (±2 weeks, T1) and 8 months (±2 weeks, T2) after enrollment.
Platelet reactivity (ADPtest AUC)
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Platelet reactivity (ASPItest AUC)
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Platelet reactivity (TRAPtest AUC)
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
High-sensitivity C-reactive protein (hs-CRP) level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Fibrinogen level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
D-dimer level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
von Willebrand factor level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Factor VIII activity
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Troponin T (high sensitivity)
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
NT-proBNP level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Blood cell morphology
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Syndecan-1 level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
ICAM-1 level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
PAI-1/tPA complex level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Heparan sulfate level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Terminal complement complex (sC5b-9) level
Time frame: From enrollment to the day of blood sampling, estimated to occur within 14 days after enrollment.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 May 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Mirko Schmidt, Prof. Dr. principal investigator
Institute of Sport Science, University of Bern, Switzerland
Dieter Thommen, Dr.med. principal investigator
Praxis für Cell-Re-Active-Training, Bern, Switzerland
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Post-Acute COVID-19 Vaccination Syndrome and Postviral Fatigue, run by University of Bern at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 12 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 5 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Mirko Schmidt, Prof. Dr. (+41 79 342 67 30, CLEAR.ispw@unibe.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Self-reported health status (EQ-VAS) (time frame: From enrollment to baseline assessment (T0)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 May 2026.