Effectiveness of mRNA Vaccines Against COVID-19 Hospitalization by Age and Chronic Medical Conditions Burden Among Immunocompetent US Adults, March-August 2021
Authors: Lewis Nathaniel M , Naioti Eric A , Self Wesley H , Ginde Adit A , Douin David J , Keipp Talbot H , Casey Jonathan D , Mohr Nicholas M , Zepeski Anne , Gaglani Manjusha , Ghamande Shekhar A , McNeal Tresa A , Shapiro Nathan I , Gibbs Kevin W , Clark Files D , Hager David N , Shehu Arber , Prekker Matthew E , Erickson Heidi L , Gong Michelle N , Mohamed Amira , Henning Daniel J , Steingrub Jay S , Peltan Ithan D , Brown Samuel M , Martin Emily T , Hubel Kinsley , Hough Catherine L , Busse Laurence W , ten Lohuis Caitlin C , Duggal Abhijit , Wilson Jennifer G , Gordon Alexandra J , Qadir Nida , Chang Steven Y , Mallow Christopher , Rivas Carolina , Babcock Hilary M , Kwon Jennie H , Exline Matthew C , Halasa Natasha , Chappell James D , Lauring Adam S , Grijalva Carlos G , Rice Todd W , Rhoads Jillian P , Stubblefield William B , Baughman Adrienne , Womack Kelsey N , Lindsell Christopher J , Hart Kimberly W , Zhu Yuwei , Schrag Stephanie J , Kobayashi Miwako , Verani Jennifer R , Patel Manish M , Tenforde Mark W ,   IVY Network Collaborators, McNeal Tresa , Ghamande Shekhar , Calhoun Nicole , Murthy Kempapura , Herrick Judy , McKillop Amanda , Hoffman Eric , Zayed Martha , Smith Michael , Settele Natalie , Ettlinger Jason , Priest Elisa , Thomas Jennifer , Arroliga Alejandro , Beeram Madhava , Kindle Ryan , Kozikowski Lori-Ann , De Souza Lesley , Ouellette Scott , Thornton-Thompson Sherell , Tyler Patrick , Mehkri Omar , Mitchell Meg , Brennan Connery , Ashok Kiran , Poynter Bryan , Stanley Nicholas , Hendrickson Audrey , Caspers Sean , Scharber Tyler , Jorgensen Jeffrey , Bowers Robert , King Jennifer , Aston Valerie , Armbruster Brent , Rothman Richard E , Nair Rahul , Chen Jen-Ting (Tina) , Karow Sarah , Robart Emily , Maldonado Paulo Nunes , Khan Maryiam , So Preston , Levitt Joe , Perez Cynthia , Visweswaran Anita , Roque Jonasel , Frankel Trevor , Garner Omai , Chandrasekaran Sukantha , Goff Jennifer , Huynh David , Ginder Adit , Douin David , Jensen Kelly , Driver Conner , Carricato Michael , Chambers Ian , Nassar Paul , Stout Lori , Sibenaller Zita , Walter Alicia , Mares Jasmine , Olson Logan , Clinansmith Bradley , Rivas Carolina , Gershengorn Hayley , McSpadden E J , Truscon Rachel , Kaniclides Anne , Thomas Lara , Bielak Ramsay , Valvano Weronika Damek , Fong Rebecca , Fitzsimmons William J , Blair Christopher , Valesano Andrew L , Gilbert Julie , Khan Akram , Krol Olivia , Zouyed Zachary , Silverman Emma , Briceno Genesis , Mills Emmanuel , Crider Christine D , Steinbock Kyle A , Paulson Thomas C , Anderson Layla A , Kampe Christy , Johnson Jakea , McHenry Rendie , Blair Marcia , Short Laura , LaRose Mary , Landreth Leigha , Hicks Madeline , Parks Lisa , Bongu Jahnavi , McDonald David , Cass Candice , Seiler Sondra , Park David , Hink Tiffany , Wallace Meghan , Burnham Carey-Ann , Arter Olivia G 
Published: December 2021

Abstract
Vaccine effectiveness (VE) against COVID-19 hospitalization was evaluated among immunocompetent adults (≥18 years) during March–August 2021 using a case-control design. Among 1669 hospitalized COVID-19 cases (11% fully vaccinated) and 1950 RT-PCR–negative controls (54% fully vaccinated), VE was 96% (95% confidence interval [CI], 93%–98%) among patients with no chronic medical conditions and 83% (95% CI, 76%–88%) among patients with ≥ 3 categories of conditions. VE was similar between those aged 18–64 years versus ≥65 years (P &gt; .05). VE against severe COVID-19 was very high among adults without chronic conditions and lessened with increasing comorbidity burden.