{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T14:51:28Z","timestamp":1793112688864,"version":"4.5.0"},"reference-count":31,"publisher":"Oxford University Press (OUP)","issue":"7","license":[{"start":{"date-parts":[[2024,9,12]],"date-time":"2024-09-12T00:00:00Z","timestamp":1726099200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/journals\/pages\/open_access\/funder_policies\/chorus\/standard_publication_model"}],"funder":[{"name":"US NIH","award":["R01GM139926"],"award-info":[{"award-number":["R01GM139926"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,7,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Postexposure vaccination has the potential to prevent or modify the course of clinical disease among those exposed to a pathogen. However, due to logistical constraints, postexposure vaccine trials have been difficult to implement in practice. In place of trials, investigators have used observational data to estimate the effectiveness or optimal timing window for postexposure vaccines, but the relationship between these analyses and those that would be conducted in a trial is often unclear. Here, we define several possible target trials for postexposure vaccination and show how, under certain conditions, they can be emulated using observational data. We emphasize the importance of the incubation period and the timing of vaccination in trial design and emulation. As an example, we specify a protocol for postexposure vaccination against mpox and provide a step-by-step description of how to emulate it using data from a health care database or contact tracing program. We further illustrate some of the benefits of the target trial approach through simulation.<\/jats:p>","DOI":"10.1093\/aje\/kwae350","type":"journal-article","created":{"date-parts":[[2024,9,5]],"date-time":"2024-09-05T21:36:02Z","timestamp":1725572162000},"page":"2037-2046","source":"Crossref","is-referenced-by-count":4,"title":["Emulating target trials of postexposure vaccines using observational data"],"prefix":"10.1093","volume":"194","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1101-2045","authenticated-orcid":false,"given":"Christopher","family":"Boyer","sequence":"first","affiliation":[{"name":"Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health , Boston, MA 02115 ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marc","family":"Lipsitch","sequence":"additional","affiliation":[{"name":"Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health , Boston, MA 02115 ,","place":["United States"]},{"name":"Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health , Boston, MA 02115 ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2024,9,12]]},"reference":[{"key":"2025070723015359500_ref1","volume-title":"Vaccines","author":"Plotkin","year":"2012"},{"issue":"1","key":"2025070723015359500_ref2","doi-asserted-by":"publisher","first-page":"13","DOI":"10.1093\/epirev\/mxz014","article-title":"Postexposure effects of vaccines on infectious diseases","volume":"41","author":"Gallagher","year":"2019","journal-title":"Epidemiol Rev."},{"issue":"6","key":"2025070723015359500_ref3","doi-asserted-by":"publisher","first-page":"766","DOI":"10.1097\/EDE.0b013e3181875e61","article-title":"Observational studies analyzed like randomized experiments: an application to postmenopausal hormone therapy and coronary heart disease","volume":"19","author":"Hern\u00e1n","year":"2008","journal-title":"Epidemiology."},{"issue":"8","key":"2025070723015359500_ref4","doi-asserted-by":"publisher","first-page":"758","DOI":"10.1093\/aje\/kwv254","article-title":"Using big data to emulate a target trial when a randomized trial is not available","volume":"183","author":"Hern\u00e1n","year":"2016","journal-title":"Am J Epidemiol."},{"key":"2025070723015359500_ref5","doi-asserted-by":"publisher","DOI":"10.1007\/978-0-387-68636-3","volume-title":"Design and Analysis of Vaccine Studies","author":"Halloran","year":"2010"},{"issue":"7","key":"2025070723015359500_ref6","doi-asserted-by":"publisher","first-page":"973","DOI":"10.1086\/378357","article-title":"Effectiveness of postexposure vaccination for the prevention of smallpox: results of a Delphi analysis","volume":"188","author":"Massoudi","year":"2003","journal-title":"J Infect Dis."},{"issue":"45","key":"2025070723015359500_ref7","doi-asserted-by":"publisher","first-page":"5192","DOI":"10.1016\/j.vaccine.2013.08.039","article-title":"The effects of post-exposure smallpox vaccination on clinical disease presentation: addressing the data gaps between historical epidemiology and modern surrogate model data","volume":"31","author":"Keckler","year":"2013","journal-title":"Vaccine."},{"key":"2025070723015359500_ref8","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.k182","article-title":"How to estimate the effect of treatment duration on survival outcomes using observational data","volume":"360","author":"Hern\u00e1n","year":"2018","journal-title":"BMJ."},{"issue":"4","key":"2025070723015359500_ref9","doi-asserted-by":"publisher","first-page":"492","DOI":"10.1093\/aje\/kwm324","article-title":"Immortal time bias in pharmacoepidemiology","volume":"167","author":"Suissa","year":"2008","journal-title":"Am J Epidemiol."},{"issue":"12","key":"2025070723015359500_ref10","doi-asserted-by":"publisher","first-page":"1205","DOI":"10.1007\/s10654-022-00929-7","article-title":"Emulation of a target trial with sustained treatment strategies: an application to prostate cancer using both inverse probability weighting and the g-formula","volume":"37","author":"Smith","year":"2022","journal-title":"Eur J Epidemiol."},{"key":"2025070723015359500_ref11","doi-asserted-by":"publisher","article-title":"The role of grace periods in comparative effectiveness studies of different medications","author":"Wanis","DOI":"10.1093\/jrsssa\/qnae002"},{"issue":"3","key":"2025070723015359500_ref12","doi-asserted-by":"publisher","first-page":"548","DOI":"10.1016\/j.vaccine.2023.12.066","article-title":"JYNNEOS\u2122 effectiveness as post-exposure prophylaxis against mpox: challenges using real-world outbreak data","volume":"42","author":"Rosen","year":"2024","journal-title":"Vaccine."},{"issue":"7","key":"2025070723015359500_ref13","doi-asserted-by":"publisher","first-page":"615","DOI":"10.1001\/jama.2022.12513","article-title":"The WHO declaration of monkeypox as a global public health emergency","volume":"328","author":"Nuzzo","year":"2022","journal-title":"JAMA."},{"key":"2025070723015359500_ref14","article-title":"Interim Clinical Considerations for Use of Vaccine for Mpox Prevention in the United States","author":"Centers for Disease Control and Prevention","year":"2023"},{"issue":"3","key":"2025070723015359500_ref15","first-page":"87","article-title":"Der Einflu\u00df Des Impfstatus Auf Die Klinische Pockenform Und Den Krankheitsausgang","volume":"117","author":"Kecmanaov\u0107","year":"1975","journal-title":"MMW Munch Med Wochenschr."},{"issue":"4","key":"2025070723015359500_ref16","doi-asserted-by":"publisher","first-page":"303","DOI":"10.1093\/oxfordjournals.aje.a121615","article-title":"The 1972 smallpox outbreak in Khulna municipality, Bangladesh: II. 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