{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,8,31]],"date-time":"2025-08-31T17:10:21Z","timestamp":1756660221890,"version":"3.44.0"},"reference-count":40,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2025,4,28]],"date-time":"2025-04-28T00:00:00Z","timestamp":1745798400000},"content-version":"unspecified","delay-in-days":117,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Child Health Evaluative Sciences, The Hospital for Sick Children","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]},{"DOI":"10.13039\/100009384","name":"Aga Khan Foundation Canada","doi-asserted-by":"publisher","award":["GCC02"],"award-info":[{"award-number":["GCC02"]}],"id":[{"id":"10.13039\/100009384","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004828","name":"Grand Challenges Canada","doi-asserted-by":"publisher","award":["TTS-1810-21048"],"award-info":[{"award-number":["TTS-1810-21048"]}],"id":[{"id":"10.13039\/501100004828","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["bmjph"],"accepted":{"date-parts":[[2025,3,14]]},"published-print":{"date-parts":[[2025,1]]},"abstract":"<jats:sec>\n                  <jats:title>Introduction<\/jats:title>\n                  <jats:p>Robust estimates of COVID-19 prevalence in settings with limited capacity for SARS-CoV-2 molecular and serologic testing are scarce. We aimed to describe the epidemiology of confirmed and probable COVID-19 in Gilgit-Baltistan, and to develop a symptom-based predictive model to identify infected but undiagnosed individuals with COVID-19.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>We conducted a cross-sectional survey in 10 257 randomly selected households in Gilgit-Baltistan from June to August 2021. Data regarding SARS-CoV-2 testing, healthcare worker (HCW) diagnoses, symptoms and outcomes since March 2020 were self-reported by households. \u2018Confirmed\/probable\u2019 infection was defined as a positive test, HCW COVID-19 diagnosis or HCW pneumonia diagnosis with COVID-19-positive contact. Robust Poisson regression was conducted to assess differences in symptoms, outcomes and SARS-CoV-2 testing rates. We developed a symptom-based machine learning model to differentiate confirmed\/probable infections from those with negative tests. We applied this model to untested respondents to estimate the total prevalence of SARS-CoV-2 infection.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Data were collected for 77 924 people. Overall, 314 (0.5%) had confirmed\/probable infections, 3263 (4.4%) had negative tests and 74 347 (95.1%) were untested. Children were tested less often than adults (adjusted prevalence ratio (aPR) 0.08, 95% CI 0.06 to 0.12 for ages 1\u20134 years vs 30\u201339 years), while males were tested more often than females (aPR 1.51, 95% CI 1.40 to 1.63). In the predictive model, area under the receiver operating characteristic curve was 0.92 (95% CI 0.90 to 0.93). We estimate there were 8\u201317 total SARS-CoV-2 infections for each positive test (8\u201317:1). The ratio of estimated to confirmed cases was higher for ages 1\u20134 years (211\u2013480:1), 5\u20139 years (80\u2013185:1) and for females (13\u201325:1).<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>From March 2020 to August 2021, the majority of SARS-CoV-2 infections in Gilgit-Baltistan went unconfirmed, particularly among women and children. Predictive models which incorporate self-reported symptoms may improve understanding of the burden of disease in settings lacking diagnostic capacity.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/bmjph-2024-001255","type":"journal-article","created":{"date-parts":[[2025,4,28]],"date-time":"2025-04-28T20:00:29Z","timestamp":1745870429000},"page":"e001255","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Estimation of unconfirmed COVID-19 cases from a cross-sectional survey of &gt;10 000 households and a symptom-based machine learning model in Gilgit-Baltistan, Pakistan"],"prefix":"10.1136","volume":"3","clinical-trial-number":[{"clinical-trial-number":"nct04798833","registry":"10.18810\/clinical-trials-gov"}],"author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7823-1912","authenticated-orcid":false,"given":"Daniel S","family":"Farrar","sequence":"first","affiliation":[{"name":"Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lisa G","family":"Pell","sequence":"additional","affiliation":[{"name":"Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yasin","family":"Muhammad","sequence":"additional","affiliation":[{"name":"Gilgit Regional Office, Aga Khan Health Service Pakistan, Gilgit, Gilgit-Baltistan, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sher","family":"Hafiz Khan","sequence":"additional","affiliation":[{"name":"Gilgit Regional Office, Aga Khan Health Service Pakistan, Gilgit, Gilgit-Baltistan, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lauren","family":"Erdman","sequence":"additional","affiliation":[{"name":"Vector Institute, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada"},{"name":"Cincinnati Children\u2019s Hospital Medical Center, Cincinnati, Ohio, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Diego G","family":"Bassani","sequence":"additional","affiliation":[{"name":"Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada"},{"name":"Department of Pediatrics, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada"},{"name":"Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zachary","family":"Tanner","sequence":"additional","affiliation":[{"name":"Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7425-3113","authenticated-orcid":false,"given":"Imran Ahmed","family":"Chauhadry","sequence":"additional","affiliation":[{"name":"Centre of Excellence in Women and Child Health, The Aga Khan University, Karachi, Sindh, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Muhammad","family":"Karim","sequence":"additional","affiliation":[{"name":"Centre of Excellence in Women and Child Health, The Aga Khan University, Karachi, Sindh, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Falak","family":"Madhani","sequence":"additional","affiliation":[{"name":"Aga Khan Health Service Pakistan, Karachi, Sindh, Pakistan"},{"name":"Brain and Mind Institute, The Aga Khan University, Karachi, Sindh, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shariq","family":"Paracha","sequence":"additional","affiliation":[{"name":"Aga Khan Health Service Pakistan, Karachi, Sindh, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masood","family":"Ali Khan","sequence":"additional","affiliation":[{"name":"Gilgit Regional Office, Aga Khan Health Service Pakistan, Gilgit, Gilgit-Baltistan, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4192-8406","authenticated-orcid":false,"given":"Sajid","family":"Soofi","sequence":"additional","affiliation":[{"name":"Centre of Excellence in Women and Child Health, The Aga Khan University, Karachi, Sindh, Pakistan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Monica","family":"Taljaard","sequence":"additional","affiliation":[{"name":"Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Ontario, Canada"},{"name":"School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rachel F","family":"Spitzer","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Ontario, Canada"},{"name":"Section of Gynecology, The Hospital for Sick Children, Toronto, 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