SARS-CoV-2

Amsterdam Long COVID muscle-biopsy PEM cohort (Appelman)

Case-control · N=46 · control Healthy convenience · 1 obs · max follow-up n/r mo

Measures: Skeletal muscle pathology (biopsy)

Small longitudinal case-control study (25 long COVID patients with PEM vs 21 healthy controls) and the only cohort in this database with tissue-level objective measures: a two-day cardiopulmonary exercise test to induce post-exertional malaise, with skeletal muscle biopsies before and after. It documented exercise-induced myopathy, metabolic disturbance, and amyloid-containing deposits that worsened after PEM. Included for the objective-measures and PEM-assessment gap matrices rather than for symptom prevalence; not denominator-defined for prevalence estimation.

Bergen COVID-19 home-isolated cohort (Blomberg)

Prospective (inception) · N=312 · control None · 7 obs · max follow-up 6 mo

Measures: Any persistent symptom, Cognitive dysfunction, Dyspnoea, Fatigue, Loss of smell/taste, Memory impairment

Notable because it captured a near-complete community denominator (82% of local cases) and included predominantly mild, home-isolated patients, showing that persistent symptoms at 6 months affect even young adults with mild acute disease. No unexposed comparator.

Jinyintan (Wuhan) COVID-19 discharge cohort (Huang)

Prospective (non-inception) · N=1733 · control Unexposed (matched) · 2 obs · max follow-up 24 mo

Measures: Fatigue

Large prospective survivor cohort with matched community controls at later timepoints. Integrity caveat: the 6-month paper received a Lancet Expression of Concern (2022) and was retracted and republished (2023) after some variables were found to have been disordered; the principal conclusions were upheld in the republished version and in the 1- and 2-year follow-ups. Retained here with this replication note precisely because the database records integrity status rather than hiding it.

Patient-Led Long COVID international cohort (Davis 2021)

Survey · N=3762 · control None · 7 obs · max follow-up 7 mo

Measures: Cognitive dysfunction, Fatigue, Not working due to illness, Post-exertional malaise

Deliberately included as a methodologically weak but historically pivotal cohort: a large (n=3762, 56 countries) self-selected online convenience sample recruited through patient support communities, with no control group, no laboratory confirmation for most respondents, and self-reported outcomes. Its breadth of symptom characterisation (203 symptoms across 10 organ systems) is unmatched, but the design cannot estimate population prevalence. Useful in the gap matrix to contrast against denominator-defined cohorts.

PHOSP-COVID (UK post-hospitalisation COVID-19)

Prospective (non-inception) · N=1965 · control None · 2 obs · max follow-up 12 mo

Measures: Felt fully recovered

Large multicentre prospective cohort of hospitalised COVID-19 survivors with an active biobank and deep phenotyping/inflammation profiling. Full recovery was reported by only about a quarter of participants and did not improve meaningfully between 5 months and 1 year. No unexposed comparison group.