Bergen COVID-19 home-isolated cohort (Blomberg)

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Design notes & limitations. 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.

Identity & trigger

Cohort id: blomberg-2021-bergen-covid
Aliases: Bergen COVID-19 Research Cohort
Outbreak / event: COVID-19 pandemic (Bergen, Norway, first wave 2020)
Pathogen: SARS-CoV-2 (Virus)
Exposure ascertainment: pcr

Design

Design: Prospective (inception)
Denominator defined: Yes
Denominator method: 82% of all laboratory-confirmed COVID-19 cases in Bergen during the first pandemic wave, enrolled near acute infection; comprises 247 home-isolated and 65 hospitalised patients.
Recruitment: community
Time zero: Acute PCR-confirmed SARS-CoV-2 infection (month)
Control group: None

Size & attrition

Enrolled: 312
Analysed / enrolled: 312/312 (100%)
Max follow-up (months): 6

Biospecimens

Specimens: Yes
Types: serum
Acute-phase specimens: Yes
Biobank: active
External access: collaboration only

Observations (7)

Symptoms

21% Proportion

Measure: Fatigue sym:fatigue
As worded: “fatigue”
Population: subgroup · denominator Symptomatic subset · N=n=61
Timing: 6 mo (3-6 mo) · ref Current
Method: Structured checklist
Comparator: no comparator
Comparability signature: 0d684c8005 — measure sym:fatigue · Structured checklist · ref Current · denom Symptomatic subset · 3-6 mo · Proportion
Provenance: Results (home-isolated adults 16-30: fatigue 21%, 13 of 61) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

28% Proportion

Measure: Loss of smell/taste sym:anosmia-dysgeusia
As worded: “loss of taste and/or smell”
Population: subgroup · denominator Symptomatic subset · N=n=61
Timing: 6 mo (3-6 mo) · ref Current
Method: Structured checklist
Comparator: no comparator
Comparability signature: bd389ba763 — measure sym:anosmia-dysgeusia · Structured checklist · ref Current · denom Symptomatic subset · 3-6 mo · Proportion
Provenance: Results (home-isolated adults 16-30: loss of taste/smell 28%, 17 of 61) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

13% Proportion

Measure: Dyspnoea sym:dyspnea
As worded: “dyspnea”
Population: subgroup · denominator Symptomatic subset · N=n=61
Timing: 6 mo (3-6 mo) · ref Current
Method: Structured checklist
Comparator: no comparator
Comparability signature: 7b25b5f93e — measure sym:dyspnea · Structured checklist · ref Current · denom Symptomatic subset · 3-6 mo · Proportion
Provenance: Results (home-isolated adults 16-30: dyspnea 13%, 8 of 61) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

13% Proportion

Measure: Cognitive dysfunction sym:cognitive-dysfunction
As worded: “impaired concentration”
Population: subgroup · denominator Symptomatic subset · N=n=61
Timing: 6 mo (3-6 mo) · ref Current
Method: Structured checklist
Comparator: no comparator
Comparability signature: 6e6cca3ee5 — measure sym:cognitive-dysfunction · Structured checklist · ref Current · denom Symptomatic subset · 3-6 mo · Proportion
Provenance: Results (home-isolated adults 16-30: impaired concentration 13%, 8 of 61) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

11% Proportion

Measure: Memory impairment sym:memory-impairment
As worded: “memory problems”
Population: subgroup · denominator Symptomatic subset · N=n=61
Timing: 6 mo (3-6 mo) · ref Current
Method: Structured checklist
Comparator: no comparator
Comparability signature: ed1925b6db — measure sym:memory-impairment · Structured checklist · ref Current · denom Symptomatic subset · 3-6 mo · Proportion
Provenance: Results (home-isolated adults 16-30: memory problems 11%, 7 of 61) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

Functional outcomes

61% Proportion

Measure: Any persistent symptom func:any-persistent-symptom
As worded: “any persistent symptom at 6 months (whole cohort)”
Population: whole cohort · denominator Assessed at timepoint · N=n=312
Timing: 6 mo (3-6 mo) · ref Not reported
Method: Unclear · Structured symptom questionnaire (author-defined)
Comparator: no comparator
Comparability signature: b9cd776a5e — measure func:any-persistent-symptom · Unclear · ref Not reported · denom Assessed at timepoint · 3-6 mo · Proportion
Provenance: Results (61%, 189 of 312, persistent symptoms at 6 months) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

52% Proportion

Measure: Any persistent symptom func:any-persistent-symptom
As worded: “persistent symptoms at 6 months among home-isolated young adults aged 16-30”
Population: whole cohort · denominator Assessed at timepoint · N=n=61
Timing: 6 mo (3-6 mo) · ref Not reported
Method: Unclear · Structured symptom questionnaire (author-defined)
Comparator: no comparator
Comparability signature: b9cd776a5e — measure func:any-persistent-symptom · Unclear · ref Not reported · denom Assessed at timepoint · 3-6 mo · Proportion
Provenance: Results (52%, 32 of 61, young home-isolated adults) · Manual · verified OSMF research-tracker (web-verified against source) on 2026-07-20

Publications

Blomberg B, Mohn KG, Brokstad KA, et al. (2021). Long COVID in a prospective cohort of home-isolated patients. Nature Medicine. PMID 34163090 · DOI 10.1038/s41591-021-01433-3 primary

Provenance & verification

Registration: n/r
Funders: Helse Vest (Western Norway Regional Health Authority), Ministry of Health and Care Services, Norway
Related cohorts: none
Symptom-inventory scope: Targeted panel
Last verified: 2026-07-20 — OSMF research-tracker (web-verified against source)