{
  "schema_version": "2.0.0",
  "id": "blomberg-2021-bergen-covid",
  "name": "Bergen COVID-19 home-isolated cohort (Blomberg)",
  "aliases": [
    "Bergen COVID-19 Research Cohort"
  ],
  "outbreak_event": "COVID-19 pandemic (Bergen, Norway, first wave 2020)",
  "pathogen_id": "sars-cov-2",
  "pathogen_class": "virus",
  "exposure_ascertainment": "pcr",
  "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_source": "community",
  "time_zero_definition": "Acute PCR-confirmed SARS-CoV-2 infection",
  "time_zero_precision": "month",
  "control_group": "none",
  "control_matching_variables": [],
  "n_source_population": null,
  "n_enrolled": 312,
  "n_analysed": 312,
  "followups": [
    {
      "months": 6,
      "n_assessed": 312,
      "n_lost": null
    }
  ],
  "max_followup_months": 6,
  "instruments": [
    "somatic-symptom-self-report"
  ],
  "case_definition": "not_applicable",
  "pem_assessed": "no",
  "objective_measures": [
    "lab_panel"
  ],
  "specimens_collected": true,
  "specimen_types": [
    "serum"
  ],
  "acute_phase_specimens": "yes",
  "storage": null,
  "biobank_status": "active",
  "consent_future_use": "unknown",
  "external_access": "collaboration_only",
  "contact": null,
  "registration_id": null,
  "funders": [
    "Helse Vest (Western Norway Regional Health Authority)",
    "Ministry of Health and Care Services, Norway"
  ],
  "conflicts": null,
  "data_availability": null,
  "notes": "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.",
  "publications": [
    {
      "id": "blomberg-2021",
      "title": "Long COVID in a prospective cohort of home-isolated patients",
      "authors": "Blomberg B, Mohn KG, Brokstad KA, et al.",
      "year": 2021,
      "journal": "Nature Medicine",
      "doi": "10.1038/s41591-021-01433-3",
      "pmid": "34163090",
      "url": "https://pubmed.ncbi.nlm.nih.gov/34163090/",
      "open_access": true,
      "is_primary_cohort_paper": true
    }
  ],
  "symptom_inventory_scope": "targeted_panel",
  "n_symptoms_queried": null,
  "symptom_instrument_note": null,
  "related_cohorts": [],
  "last_verified": "2026-07-20",
  "verified_by": "OSMF research-tracker (web-verified against source)",
  "harmonisation_ruleset": "pais-harmony-v1",
  "observations": [
    {
      "id": "blomberg-persist-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "func:any-persistent-symptom",
      "measure_verbatim": "any persistent symptom at 6 months (whole cohort)",
      "population": {
        "scope": "whole_cohort",
        "stratum": null,
        "denominator_basis": "assessed_at_timepoint",
        "n_assessed": 312
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "not_reported",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "unclear",
        "instrument_id": "somatic-symptom-self-report",
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 189,
        "denominator": 312,
        "percent": 61,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (61%, 189 of 312, persistent symptoms at 6 months)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "func:any-persistent-symptom",
      "measure_verbatim": "persistent symptoms at 6 months among home-isolated young adults aged 16-30",
      "population": {
        "scope": "whole_cohort",
        "stratum": null,
        "denominator_basis": "assessed_at_timepoint",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "not_reported",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "unclear",
        "instrument_id": "somatic-symptom-self-report",
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 32,
        "denominator": 61,
        "percent": 52,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (52%, 32 of 61, young home-isolated adults)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-fatigue-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "sym:fatigue",
      "measure_verbatim": "fatigue",
      "population": {
        "scope": "subgroup",
        "stratum": null,
        "denominator_basis": "symptomatic_subset",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "current",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "structured_checklist",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 13,
        "denominator": 61,
        "percent": 21,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (home-isolated adults 16-30: fatigue 21%, 13 of 61)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-anosmia-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "sym:anosmia-dysgeusia",
      "measure_verbatim": "loss of taste and/or smell",
      "population": {
        "scope": "subgroup",
        "stratum": null,
        "denominator_basis": "symptomatic_subset",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "current",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "structured_checklist",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 17,
        "denominator": 61,
        "percent": 28,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (home-isolated adults 16-30: loss of taste/smell 28%, 17 of 61)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-dyspnea-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "sym:dyspnea",
      "measure_verbatim": "dyspnea",
      "population": {
        "scope": "subgroup",
        "stratum": null,
        "denominator_basis": "symptomatic_subset",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "current",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "structured_checklist",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 8,
        "denominator": 61,
        "percent": 13,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (home-isolated adults 16-30: dyspnea 13%, 8 of 61)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-cognitive-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "sym:cognitive-dysfunction",
      "measure_verbatim": "impaired concentration",
      "population": {
        "scope": "subgroup",
        "stratum": null,
        "denominator_basis": "symptomatic_subset",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "current",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "structured_checklist",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 8,
        "denominator": 61,
        "percent": 13,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (home-isolated adults 16-30: impaired concentration 13%, 8 of 61)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "blomberg-memory-young-6mo",
      "cohort_id": "blomberg-2021-bergen-covid",
      "publication_id": "blomberg-2021",
      "schema_version": "2.0.0",
      "measure_id": "sym:memory-impairment",
      "measure_verbatim": "memory problems",
      "population": {
        "scope": "subgroup",
        "stratum": null,
        "denominator_basis": "symptomatic_subset",
        "n_assessed": 61
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "current",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "structured_checklist",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 7,
        "denominator": 61,
        "percent": 11,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results (home-isolated adults 16-30: memory problems 11%, 7 of 61)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    }
  ]
}