Estimating Vaccine Effectiveness Against Hospitalized Influenza During Pregnancy: Multicountry Protocol for a Retrospective Cohort Study

Allison L Naleway   ^{1 *} , PhD ;   Sarah Ball   ^{2 *} , ScD ;   Jeffrey C Kwong   ³ , MD ;   Brandy E Wyant   ² , MPH ;   Mark A Katz   ⁴ , MD ;   Annette K Regan   ⁵ , PhD ;   Margaret L Russell   ⁶ , MD, PhD ;   Nicola P Klein   ⁷ , MD, PhD ;   Hannah Chung   ³ , MPH ;   Kimberley A Simmonds   ⁸ , PhD ;   Eduardo Azziz-Baumgartner   ⁹ , MD ;   Becca S Feldman   ⁴ , ScD ;   Avram Levy   ¹⁰ , PhD ;   Deshayne B Fell   ¹¹ , PhD ;   Steven J Drews   ¹² , PhD ;   Shikha Garg   ⁹ , MD ;   Paul Effler   ¹³ , MD ;   Noam Barda   ⁴ , MD ;   Stephanie A Irving   ¹ , MHS ;   Patricia Shifflett   ² , MS, RN ;   Michael L Jackson   ¹⁴ , PhD ;   Mark G Thompson   ^{9 *} , PhD

¹ Kaiser Permanente Northwest, Center for Health Research, Portland, OR, United States

² Abt Associates, Inc, Cambridge, MA, United States

³ ICES, Toronto, ON, Canada

⁴ Chief Physician's Office, Clalit Health Services, Clalit Research Institute, Tel Aviv, Israel

⁵ School of Public Health, Curtin University, Perth, Western Australia, Australia

⁶ Cumming School of Medicine, University of Calgary, Calgary, AB, Canada

⁷ Kaiser Permanente Vaccine Study Center, Oakland, CA, United States

⁸ Alberta Health, Edmonton, AB, Canada

⁹ Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA, United States

¹⁰ PathWest Laboratory Medicine Western Australia, Perth, Australia

¹¹ School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada

¹² Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada

¹³ Western Australia Department of Health, Perth, Australia

¹⁴ Kaiser Permanente Washington Health Research Institute, Seattle, WA, United States

*these authors contributed equally