Interim Estimates of Vaccine Effectiveness of Pfizer-BioNTech and Moderna COVID-19 Vaccines Among Health Care Personnel — 33 U.S. Sites, January–March 2021

Pilishvili, Tamara; Fleming-Dutra, Katherine E.; Farrar, Jennifer L.; Gierke, Ryan; Mohr, Nicholas M.; Talan, David A.; Krishnadasan, Anusha; Harland, Karisa K.; Smithline, Howard A.; Hou, Peter C.; Lee, Lilly C.; Lim, Stephen C.; Moran, Gregory J.; Krebs, Elizabeth; Steele, Mark; Beiser, David G.; Faine, Brett; Haran, John P.; Nandi, Utsav; Schrading, Walter A.; Chinnock, Brian; Henning, Daniel J.; LoVecchio, Frank; Nadle, Joelle; Barter, Devra; Brackney, Monica; Britton, Amber; Marceaux-Galli, Kaytlynn; Lim, Sarah; Phipps, Erin C.; Dumyati, Ghinwa; Pierce, Rebecca; Markus, Tiffanie M.; Anderson, Deverick J.; Debes, Amanda K.; Lin, Michael; Mayer, Jeanmarie; Babcock, Hilary M.; Safdar, Nasia; Fischer, Marc; Singleton, Rosalyn; Chea, Nora; Magill, Shelley S.; Verani, Jennifer; Schrag, Stephanie; Yousaf, Anna; Chung, Yunmi; Onukwube, Jennifer; Xing, Wei; Clinansmith, Bradley; Uribe, Lisandra; Poronsky, Kye E.; Hashimoto, Dean M.; Bahamon, Monica; St. Romain, Michelle; Kean, Efrat; Stubbs, Amy; Roy, Sara; Volturo, Gregory; Galbraith, James; Crosby, James C.; Fuentes, Megan R.; Mulrow, Mary; Lee, Jane; Johnston, Helen; Hansen, AmberJean; Fridkin, Scott K.; Wilson, Lucy E.; Lovett, Sara; Christian, Melissa; Myers, Christopher; Ocampo, Valerie L.S.; Talbot, Keipp; Seidelman, Jessica; Milstone, Aaron M.; Hayden, Mary; Samore, Matthew; Kwon, Jennie H.; Shirley, Daniel; Dillard, Denise; Dobson, Jennifer

Throughout the COVID-19 pandemic, health care personnel (HCP) have been at high risk for exposure to SARS-CoV-2, the virus that causes COVID-19, through patient interactions and community exposure (1). The Advisory Committee on Immunization Practices recommended prioritization of HCP for COVID-19 vaccination to maintain provision of critical services and reduce spread of infection in health care settings (2). Early distribution of two mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna) to HCP allowed assessment of the effectiveness of these vaccines in a real-world setting. A test-negative case-control study is underway to evaluate mRNA COVID-19 vaccine effectiveness (VE) against symptomatic illness among HCP at 33 U.S. sites across 25 U.S. states. Interim analyses indicated that the VE of a single dose (measured 14 days after the first dose through 6 days after the second dose) was 82% (95% confidence interval [CI] = 74%-87%), adjusted for age, race/ethnicity, and underlying medical conditions. The adjusted VE of 2 doses (measured ≥7 days after the second dose) was 94% (95% CI = 87%-97%). VE of partial (1-dose) and complete (2-dose) vaccination in this population is comparable to that reported from clinical trials and recent observational studies, supporting the effectiveness of mRNA COVID-19 vaccines against symptomatic disease in adults, with strong 2-dose protection.