Long COVID vs PACVS: symptoms, biomarkers, trials and research
A data-driven comparison of Long COVID and Post-Acute COVID-19 Vaccination Syndrome (PACVS) built from the Open Source Medicine Foundation biomarker atlases, PubMed literature feeds, ClinicalTrials.gov registry extract and post-acute infection syndrome (PAIS) cohort database.
Both syndromes are attributed to exposure to the SARS-CoV-2 spike protein, by infection in one case and by vaccination in the other, and patients describe overlapping symptom clusters. The evidence base is radically asymmetric: Long COVID has hundreds of registered trials and thousands of papers; PACVS has a handful of each.
What each condition is
Long COVID
Also known as: PASC, Post-Acute Sequelae of COVID-19, Post-COVID-19 condition
Long COVID describes symptoms that persist or emerge more than three months after SARS-CoV-2 infection and cannot be explained by another diagnosis. The World Health Organization calls it post-COVID-19 condition; the US National Institutes of Health uses the term PASC. Common features include fatigue, post-exertional symptom exacerbation, cognitive difficulties, orthostatic intolerance, breathlessness and chest pain. Because the triggering infection is known and recent, Long COVID has attracted large prospective cohorts (RECOVER, PHOSP-COVID) and the largest clinical-trial pipeline of any post-infectious illness.
Atlas scope: Molecular, metabolic, and immunological alterations reported in post-acute sequelae of COVID-19 (PASC / long COVID) compared to healthy controls and fully recovered individuals.
OSMF resources: biomarker atlas · literature feed
Post-Acute COVID-19 Vaccination Syndrome
Also known as: PCVS, Post-Vac Syndrome, Post-vaccination syndrome
PACVS (also written PCVS or post-vac syndrome) refers to persistent, Long COVID-like symptoms that begin shortly after SARS-CoV-2 vaccination and last for months in a small subset of recipients. It is not a recognised diagnostic entity in most countries and is defined differently across the handful of registry and survey cohorts that exist (Marburg, Yale LISTEN, VITAE). Research is early-stage: the literature is small, the biomarker evidence comes mainly from case series, and only a few interventional studies are registered.
Atlas scope: Molecular, serologic, immunologic, and functional alterations reported in Post-Acute COVID-19 Vaccination Syndrome (PACVS) — persistent symptoms following SARS-CoV-2 vaccination — from PACVS/PCVS primary studies and post-vaccination adverse-event literature.
OSMF resources: biomarker atlas · literature feed
Side-by-side summary
| Measure | Long COVID | PACVS |
|---|---|---|
| Biomarkers catalogued | 77 | 32 |
| Biomarker categories covered | metabolic (23), inflammatory (14), vascular (8), immune (7), coagulation (6), proteomic (5), lipidomic (4), neurological (4), microbiome (4), viral (2) | autoimmune (8), functional (8), spike (4), molecular (4), metabolic (3), serologic (2), inflammatory (2), proteomic (1) |
| Markers with LOINC codes | 25 | 3 |
| Literature studies tracked | 75 | 15 |
| Most recent tracked study | 07 Jul 2026 | 24 Sep 2026 |
| Registered trials (all statuses) | 341 | 2 |
| Recruiting / not yet recruiting | 81 | 2 |
| Active, not recruiting | 26 | 0 |
| Completed | 150 | 0 |
| Terminated / withdrawn / suspended | 27 | 0 |
| Unknown status | 57 | 0 |
| Named cohorts in PAIS database | 8 | 4 |
| Therapeutic agents tracked | 405 | 7 |
Trial condition matching: Long COVID uses the registry’s mapped condition label; PACVS uses keyword matching on registry condition and title fields. Trials listing both conditions: 1.
Shared biomarkers (5)
Markers catalogued in both atlases, matched by normalised name or LOINC code. Rows marked direction differs are reported to change in opposite or inconsistent directions across the two literatures, which may reflect different comparison groups, assays or disease stages rather than true biology.
| Biomarker | Category | Direction in Long COVID | Direction in PACVS | Matched by | Sources |
|---|---|---|---|---|---|
| Interleukin-6 (IL-6) IL-6 in PACVS | inflammatory | Increased vs HC, R | Increased vs HC | LOINC 26881-5 | Lai et al. 2023; Mundorf et al. 2024 |
| Interleukin-8 (IL-8) IL-8 in PACVS | inflammatory | Increased vs HC | Increased vs HC | name | Thomas et al. 2024; Mundorf et al. 2024 |
| Ferritin Ferritin index in PACVS direction differs | inflammatory / metabolic | Mixed / conflicting vs HC | Decreased vs HC | LOINC 2276-4 | Thomas et al. 2024; Mundorf et al. 2024 |
| Neurofilament light chain (NfL) | neurological / functional | Increased vs HC | Increased vs HC | LOINC 94635-5 | Lai et al. 2023; Mundorf et al. 2024 |
| Anti-GPCR autoantibodies Anti-GPCR autoantibodies (panel) in PACVS | immune / autoimmune | Increased vs HC | Increased vs HC | name | Wilhelm et al. 2026; Mantovani et al. 2024 |
Distinct biomarkers
Top 15 markers catalogued for one condition but not matched in the other. Full lists are on the Long COVID atlas and the PACVS atlas.
Only in Long COVID atlas (72)
- Tumor Necrosis Factor-α (TNF-α) Increased inflammatory
- Interleukin-1α (IL-1α) Increased inflammatory
- C-Reactive Protein (CRP) Increased inflammatory
- Soluble CD14 (sCD14) Increased inflammatory
- Flt-1 / sVEGFR-1 Increased inflammatory
- CCL4 (MIP-1β) Increased inflammatory
- Cystatin D (CST5) Increased inflammatory
- Pro-inflammatory cytokines (composite) Decreased inflammatory
- Transforming Growth Factor-β (TGF-β) Increased inflammatory
- Interleukin-10 (IL-10) Mixed / conflicting inflammatory
- Serum Amyloid A (SAA) Increased inflammatory
- ATP (plasma) Decreased metabolic
- Serine Decreased metabolic
- Sarcosine Decreased metabolic
- Aspartate Decreased metabolic
+57 more in the atlas.
Only in PACVS atlas (27)
- S1 in CD16+ monocytes Increased spike
- Circulating spike (post-mRNA myocarditis) Increased spike
- Spike in cutaneous lesions Increased spike
- Spike in neurological tissue Increased spike
- Anti-Spike (Anti-S) antibodies Increased serologic
- Anti-Nucleocapsid (Anti-N) antibodies Decreased serologic
- 2P proteotypic peptides (K986P/V987P) Increased molecular
- Wild-type viral spike peptides Decreased molecular
- BNT162b2 vaccine mRNA (qPCR) Mixed / conflicting molecular
- Vaccine mRNA (hybrid 3'UTR motifs) Mixed / conflicting molecular
- Anti-ACE2 autoantibodies Increased autoimmune
- Anti-AT1R (angiotensin II type 1 receptor) Increased autoimmune
- Anti-MAS1 receptor autoantibodies Increased autoimmune
- Anti-STAB1 autoantibodies Increased autoimmune
- Anti-ADRA2A (α2B adrenergic receptor) Decreased autoimmune
+12 more in the atlas.
Overlapping therapeutics under investigation (4)
Agents that appear in registered trials or the OSMF therapeutic-agent database for both Long COVID and PACVS. Inclusion means an agent is being studied, not that it works.
- Combined Metabolic Modulator
- Intravenous Immunoglobulin (IVIG)
- N-Acetylcysteine (NAC)
- Rice Protein Powder With Vitamin C
Trials enrolling both conditions (1)
- NCT06967428 · Effect of Metabolic Modulation on a Post-acute COVID-19 Vaccination Syndrome (PACVS) Cohort (Not Yet Recruiting, Phase 2)
Research cohorts
Long COVID cohorts (8)
- NIH RECOVER-Adult Cohort prospective non inception, n=15,000, biobank active
- Long COVID Host Genetics Initiative GWAS registry linkage, n=6,450, biobank active
- Patient-Led Long COVID international cohort (Davis 2021) survey, n=3,762, biobank not_applicable
- PHOSP-COVID (UK post-hospitalisation COVID-19) prospective non inception, n=2,320, biobank active
- Jinyintan (Wuhan) COVID-19 discharge cohort (Huang) prospective non inception, n=1,733, biobank unknown
- Bergen COVID-19 home-isolated cohort (Blomberg) prospective inception, n=312, biobank active
- PACVS registry cohort (Semmler/Mundorf) cross sectional, n=191, biobank unknown
- Amsterdam Long COVID muscle-biopsy PEM cohort (Appelman) case control, n=46, biobank unknown
PACVS cohorts (4)
- Post-Vac-Syndrom Deutschland patient survey survey, n=777, biobank not_applicable
- VITAE vaccine-injury survey (Halma & Varon) survey, n=706, biobank not_applicable
- Yale LISTEN post-vaccination syndrome cohort (Krumholz) survey, n=241, biobank active
- PACVS registry cohort (Semmler/Mundorf) cross sectional, n=191, biobank unknown
Recent research
Latest Long COVID studies
Latest PACVS studies
Frequently asked questions
Can you have both Long COVID and PACVS?
They are not mutually exclusive. Both are diagnosed clinically, and a person can meet criteria for Long COVID and PACVS at the same time. In the OSMF data the two conditions share 5 catalogued biomarkers, 1 registered trial list both conditions, and 1 cohort in the PAIS database is relevant to both. Overlap in a dataset is not evidence that one condition causes the other.
How do the biomarker profiles differ?
Long COVID has 77 catalogued markers, led by metabolic (23), inflammatory (14), vascular (8). PACVS has 32, led by autoimmune (8), functional (8), spike (4). 5 markers appear in both atlases, and 1 of those are reported to move in different directions (Ferritin). Categories unique to Long COVID: coagulation, immune, lipidomic, microbiome, neurological, vascular, viral; unique to PACVS: autoimmune, functional, molecular, serologic, spike.
Which has more active clinical trials?
Long COVID has more: 107 active or recruiting trials versus 2 for PACVS (registry snapshot 07 Oct 2026). Totals including completed, terminated and unknown-status studies are 341 for Long COVID and 2 for PACVS. Condition matching for PACVS relies on keyword matching of registry condition fields and may miss trials. Trial counts measure research attention, not treatment efficacy.
Which condition has more recent research?
OSMF tracks 75 recent PubMed-indexed studies for Long COVID (latest 07 Jul 2026) and 15 for PACVS (latest 24 Sep 2026). The feeds hold a rolling window of recent publications, so they indicate current publication pace rather than lifetime output. See the Long COVID feed and the PACVS feed for the full lists.
Are the same treatments being studied for both?
4 agents appear in the trial registry or therapeutic-agent database for both conditions, including Combined Metabolic Modulator, Intravenous Immunoglobulin (IVIG), N-Acetylcysteine (NAC), Rice Protein Powder With Vitamin C. All of these are investigational for these indications; none is an approved treatment for either condition. Overlap usually reflects shared hypotheses (immune modulation, autonomic support, antiviral or anti-inflammatory strategies) rather than demonstrated efficacy.
Which has larger research cohorts?
The PAIS cohort database lists 8 named cohorts for Long COVID and 4 named cohorts for PACVS, the largest being NIH RECOVER-Adult Cohort (15,000 enrolled) and Post-Vac-Syndrom Deutschland patient survey (777 enrolled). Cohorts with stored biospecimens and open external access are the most useful for cross-condition biomarker validation.
Related comparisons
Cite this page
@misc{osmf_longcovid_vs_pacvs,
author = {Open Source Medicine Foundation},
title = {Long COVID vs PACVS: symptoms, biomarkers, trials and research compared},
year = {2026},
howpublished = {\url{https://research.opensourcemed.info/compare/long-covid-vs-pacvs.html}},
note = {Data as of 2026-10-07}
}Get OSMF research updates
New biomarker, trial and cohort data, summarised for patients and researchers.
Last updated 07 Oct 2026 (page build). Underlying data: literature feeds 07 Jul 2026 / 07 Oct 2026; trial registry 07 Oct 2026; atlases 29 Jun 2026 / 30 Jun 2026. Generated by scripts/build_compare_pages.py.