{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T05:17:37Z","timestamp":1785302257616,"version":"3.55.0"},"reference-count":30,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T00:00:00Z","timestamp":1764892800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0"},{"start":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T00:00:00Z","timestamp":1764892800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0"}],"funder":[{"DOI":"10.13039\/100004319","name":"Pfizer Inc","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100004319","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Infect Dis Ther"],"published-print":{"date-parts":[[2026,1]]},"DOI":"10.1007\/s40121-025-01259-3","type":"journal-article","created":{"date-parts":[[2025,12,5]],"date-time":"2025-12-05T11:37:20Z","timestamp":1764934640000},"page":"327-343","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Impact of Risk Stacking on COVID-19\u2013Related Healthcare Utilization: A Real-World Retrospective Cohort Study"],"prefix":"10.1007","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6927-9765","authenticated-orcid":false,"given":"Frank R.","family":"Ernst","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leah","family":"McGrath","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maya","family":"Reimbaeva","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura E.","family":"Choi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irini","family":"Zografaki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lili","family":"Jiang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Santiago M. C.","family":"Lopez","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mary M.","family":"Moran","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura","family":"Puzniak","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luis","family":"Jodar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel","family":"Curcio","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alejandro","family":"Can\u00e9","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2025,12,5]]},"reference":[{"key":"1259_CR1","unstructured":"COVID-19 Treatment Guidelines Panel. Coronavirus disease 2019 (COVID-19) treatment guidelines. National Institutes of Health. Available at: https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK570371\/pdf\/Bookshelf_NBK570371.pdf. Accessed Apr 16, 2025."},{"key":"1259_CR2","unstructured":"Centers for Disease Control and Prevention (CDC). People with certain medical conditions and COVID-19 risk factors. Available at: https:\/\/www.cdc.gov\/covid\/risk-factors\/?CDC_AAref_Val=https:\/\/www.cdc.gov\/coronavirus\/2019-ncov\/need-extra-precautions\/people-with-medical-conditions.html. Accessed Apr 16, 2025."},{"key":"1259_CR3","unstructured":"Centers for Disease Control and Prevention (CDC). Underlying conditions and the higher risk for severe COVID-19. Available at: https:\/\/www.cdc.gov\/covid\/hcp\/clinical-care\/underlying-conditions.html?CDC_AAref_Val=https:\/\/www.cdc.gov\/coronavirus\/2019-ncov\/hcp\/clinical-care\/underlyingconditions.html. Accessed Apr 16, 2025."},{"key":"1259_CR4","doi-asserted-by":"publisher","DOI":"10.1038\/s41572-022-00376-4","volume":"8","author":"ST Skou","year":"2022","unstructured":"Skou ST, Mair FS, Fortin M, et al. Multimorbidity. Nat Rev Dis Primers. 2022;8:48.","journal-title":"Nat Rev Dis Primers"},{"key":"1259_CR5","doi-asserted-by":"publisher","first-page":"2603","DOI":"10.1056\/NEJMoa2034577","volume":"383","author":"FP Polack","year":"2020","unstructured":"Polack FP, Thomas SJ, Kitchin N, et al. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N Engl J Med. 2020;383:2603\u201315.","journal-title":"N Engl J Med"},{"key":"1259_CR6","doi-asserted-by":"publisher","first-page":"403","DOI":"10.1056\/NEJMoa2035389","volume":"384","author":"LR Baden","year":"2021","unstructured":"Baden LR, El Sahly HM, Essink B, et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N Engl J Med. 2021;384:403\u201316.","journal-title":"N Engl J Med"},{"key":"1259_CR7","doi-asserted-by":"publisher","first-page":"99","DOI":"10.1016\/S0140-6736(20)32661-1","volume":"397","author":"M Voysey","year":"2021","unstructured":"Voysey M, Clemens SAC, Madhi SA, et al. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet. 2021;397:99\u2013111.","journal-title":"Lancet"},{"key":"1259_CR8","doi-asserted-by":"publisher","first-page":"2187","DOI":"10.1056\/NEJMoa2101544","volume":"384","author":"J Sadoff","year":"2021","unstructured":"Sadoff J, Gray G, Vandebosch A, et al. Safety and efficacy of single-dose Ad26.COV2.S vaccine against Covid-19. N Engl J Med. 2021;384:2187\u2013201.","journal-title":"N Engl J Med"},{"key":"1259_CR9","doi-asserted-by":"publisher","DOI":"10.1017\/ash.2023.447","volume":"3","author":"AR Marra","year":"2023","unstructured":"Marra AR, Kobayashi T, Callado GY, et al. The effectiveness of COVID-19 vaccine in the prevention of post-COVID conditions: a systematic literature review and meta-analysis of the latest research. Antimicrob Steward Healthc Epidemiol. 2023;3:e168.","journal-title":"Antimicrob Steward Healthc Epidemiol"},{"key":"1259_CR10","doi-asserted-by":"publisher","first-page":"1293","DOI":"10.1016\/S1473-3099(22)00320-6","volume":"22","author":"OJ Watson","year":"2022","unstructured":"Watson OJ, Barnsley G, Toor J, et al. Global impact of the first year of COVID-19 vaccination: a mathematical modelling study. Lancet Infect Dis. 2022;22:1293\u2013302.","journal-title":"Lancet Infect Dis"},{"key":"1259_CR11","doi-asserted-by":"publisher","first-page":"323","DOI":"10.1093\/cid\/ciae551","volume":"80","author":"J Hammond","year":"2025","unstructured":"Hammond J, Leister-Tebbe H, Gardner A, et al. Alleviation of COVID-19 symptoms and reduction in healthcare utilization among high-risk patients treated with nirmatrelvir\/ritonavir (NMV\/R): a phase 3 randomized trial. Clin Infect Dis. 2025;80:323\u201330.","journal-title":"Clin Infect Dis"},{"key":"1259_CR12","doi-asserted-by":"publisher","first-page":"1397","DOI":"10.1056\/NEJMoa2118542","volume":"386","author":"J Hammond","year":"2022","unstructured":"Hammond J, Leister-Tebbe H, Gardner A, et al. Oral nirmatrelvir for high-risk, nonhospitalized adults with covid-19. N Engl J Med. 2022;386:1397\u2013408.","journal-title":"N Engl J Med"},{"key":"1259_CR13","doi-asserted-by":"publisher","DOI":"10.1093\/ofid\/ofad674","volume":"11","author":"Y Shen","year":"2024","unstructured":"Shen Y, Robertson MM, Kulkarni SG, et al. Oral COVID-19 antiviral uptake among a highly vaccinated US cohort of adults with SARS-CoV-2 infection between December 2021 and October 2022. Open Forum Infect Dis. 2024;11:ofad674.","journal-title":"Open Forum Infect Dis"},{"key":"1259_CR14","unstructured":"Mathieu E, Ritchie H, Rod\u00e9s-Guirao L, et al. Coronavirus (COVID-19) vaccinations. Available at: https:\/\/ourworldindata.org\/covid-vaccinations. Accessed Apr 23, 2025."},{"key":"1259_CR15","unstructured":"Centers for Disease Control and Prevention (CDC). Interim clinical considerations for use of COVID-19 vaccines in the United States. Available at: https:\/\/www.cdc.gov\/vaccines\/covid-19\/clinical-considerations\/interim-considerations-us.html#print. Accessed Apr 24, 2024."},{"key":"1259_CR16","unstructured":"World Health Organization. COVID-19 advice for the public: getting vaccinated. Available at: https:\/\/www.who.int\/emergencies\/diseases\/novel-coronavirus-2019\/covid-19-vaccines\/advice. Accessed Apr 27, 2025."},{"key":"1259_CR17","unstructured":"Optum. Optum claims data. Available at: https:\/\/www.optum.com\/en\/business\/life-sciences\/real-world-data\/claims-data.html. Accessed Oct 6, 2024."},{"key":"1259_CR18","unstructured":"Optum. Clinformatics\u00ae Data Mart. Available at: https:\/\/www.optum.com\/content\/dam\/optum\/resources\/productSheets\/Clinformatics_for_Data_Mart.pdf. Accessed June 13, 2024."},{"key":"1259_CR19","unstructured":"US Department of Health and Human Services. Guidance regarding methods for de-identification of protected health information in accordance with the Health Insurance Portability and Accountability Act (HIPAA) privacy rule. Available at: https:\/\/www.hhs.gov\/hipaa\/for-professionals\/privacy\/special-topics\/de-identification\/index.html. Accessed June 13, 2024."},{"key":"1259_CR20","doi-asserted-by":"publisher","first-page":"651","DOI":"10.15585\/mmwr.mm7224a2","volume":"72","author":"KC Ma","year":"2023","unstructured":"Ma KC, Shirk P, Lambrou AS, et al. Genomic surveillance for SARS-CoV-2 variants: circulation of Omicron lineages\u2014United States, January 2022\u2013May 2023. MMWR Morb Mortal Wkly Rep. 2023;72:651\u20136.","journal-title":"MMWR Morb Mortal Wkly Rep"},{"key":"1259_CR21","unstructured":"Centers for Disease Control and Prevention (CDC). Archived Page: Underlying medical conditions associated with higher risk for severe COVID-19: information for healthcare professionals. Available at: https:\/\/archive.cdc.gov\/www_cdc_gov\/coronavirus\/2019-ncov\/hcp\/clinical-care\/underlyingconditions.html. Accessed May 8, 2025."},{"key":"1259_CR22","doi-asserted-by":"publisher","first-page":"E66","DOI":"10.5888\/pcd18.210123","volume":"18","author":"L Kompaniyets","year":"2021","unstructured":"Kompaniyets L, Pennington AF, Goodman AB, et al. Underlying medical conditions and severe illness among 540,667 adults hospitalized with COVID-19, March 2020\u2013March 2021. Prev Chronic Dis. 2021;18:E66.","journal-title":"Prev Chronic Dis"},{"issue":"5","key":"1259_CR23","doi-asserted-by":"publisher","first-page":"577","DOI":"10.1111\/irv.12864","volume":"15","author":"L Cummins","year":"2021","unstructured":"Cummins L, Ebyarimpa I, Cheetham N, et al. Factors associated with COVID-19 related hospitalisation, critical care admission and mortality using linked primary and secondary care data. Influenza Other Respir Viruses. 2021;15(5):577\u201388.","journal-title":"Influenza Other Respir Viruses"},{"key":"1259_CR24","doi-asserted-by":"publisher","first-page":"338","DOI":"10.1093\/cid\/ciad505","volume":"78","author":"EP Griggs","year":"2024","unstructured":"Griggs EP, Mitchell PK, Lazariu V, et al. Clinical epidemiology and risk factors for critical outcomes among vaccinated and unvaccinated adults hospitalized with COVID-19-VISION network, 10 states, June 2021\u2013March 2023. Clin Infect Dis. 2024;78:338\u201348.","journal-title":"Clin Infect Dis"},{"key":"1259_CR25","unstructured":"US Centers for Disease Control and Prevention. Vaccines for moderately to severely immunocompromised people. Available at: https:\/\/www.cdc.gov\/covid\/vaccines\/immunocompromised-people.html. Accessed Sept 9, 2024."},{"key":"1259_CR26","volume":"16","author":"VC Ezeamii","year":"2024","unstructured":"Ezeamii VC, Ofochukwu VC, Iheagwara C, et al. COVID-19 vaccination rates and predictors of uptake among adults with coronary heart disease: insight from the 2022 National Health Interview Survey. Cureus. 2024;16:e52480.","journal-title":"Cureus"},{"key":"1259_CR27","volume":"14","author":"M Riyyan","year":"2022","unstructured":"Riyyan M, Sajid S, Hotwani S, et al. Multimorbidity and its effect on self-reported adverse effects following COVID-19 vaccination. Cureus. 2022;14:e33139.","journal-title":"Cureus"},{"key":"1259_CR28","doi-asserted-by":"publisher","first-page":"1743","DOI":"10.1007\/s40121-024-01003-3","volume":"13","author":"K Penrose","year":"2024","unstructured":"Penrose K, Srivastava A, Shen Y, et al. Perceived risk for severe COVID-19 and oral antiviral use among antiviral-eligible US adults. Infect Dis Ther. 2024;13:1743\u201357.","journal-title":"Infect Dis Ther"},{"key":"1259_CR29","doi-asserted-by":"publisher","first-page":"57","DOI":"10.15585\/mmwr.mm7303a2","volume":"73","author":"PA Monach","year":"2024","unstructured":"Monach PA, Anand ST, Fillmore NR, La J, Branch-Elliman W. Underuse of antiviral drugs to prevent progression to severe COVID-19 - veterans health administration, march-september 2022. MMWR Morb Mortal Wkly Rep. 2024;73:57\u201361.","journal-title":"MMWR Morb Mortal Wkly Rep"},{"key":"1259_CR30","doi-asserted-by":"publisher","DOI":"10.1001\/jamanetworkopen.2022.51833","volume":"6","author":"SY Tartof","year":"2023","unstructured":"Tartof SY, Slezak JM, Puzniak L, et al. Analysis of mRNA COVID-19 vaccine uptake among immunocompromised individuals in a large US health system. JAMA Netw Open. 2023;6:e2251833.","journal-title":"JAMA Netw Open"}],"container-title":["Infectious Diseases and Therapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s40121-025-01259-3.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1007\/s40121-025-01259-3","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1007\/s40121-025-01259-3.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T11:27:56Z","timestamp":1767871676000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1007\/s40121-025-01259-3"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,5]]},"references-count":30,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,1]]}},"alternative-id":["1259"],"URL":"https:\/\/doi.org\/10.1007\/s40121-025-01259-3","relation":{},"ISSN":["2193-8229","2193-6382"],"issn-type":[{"value":"2193-8229","type":"print"},{"value":"2193-6382","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,5]]},"assertion":[{"value":"15 July 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"23 October 2025","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"5 December 2025","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Frank R. Ernst, Leah McGrath, Maya Reimbaeva, Laura E. Choi, Irini Zografaki, Lili Jiang, Santiago M.C. Lopez, Mary M. Moran, Laura Puzniak, Luis Jodar, Daniel Curcio, and Alejandro Can\u00e9 were employees of Pfizer at the time of the study and may hold Pfizer stock or stock options. Dr. McGrath\u2019s affiliation has changed and is currently with AbbVie. Following his retirement from Pfizer, Dr. Jodar is currently unaffiliated.","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Conflicts of Interests"}},{"value":"The study was exempt from institutional review board (IRB) approval, ethics committee review, or participant informed consent due to the deidentified nature of the database and compliance with the Health Insurance Portability and Accountability Act (HIPAA) Privacy Rule [\n                      \n                      ,\n                      \n                      ]. Access to the database used in this study was granted through agreements established with Optum\n                      \u00ae\n                      .","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethical Approval"}}]}}