Effectiveness of a Third Dose of Pfizer-BioNTech and Moderna Vaccines in Preventing COVID-19 Hospitalization Among Immunocompetent and Immunocompromised Adults — United States, August–December 2021
Authors: Mark W. Tenforde, Manish M. Patel, Manjusha Gaglani, Adit A. Ginde, David J. Douin, H. Keipp Talbot, Jonathan D. Casey, Nicholas M. Mohr, Anne Zepeski, Tresa McNeal, Shekhar Ghamande, Kevin W. Gibbs, D. Clark Files, David N. Hager, Arber Shehu, Matthew E. Prekker, Heidi L. Erickson, Michelle N. Gong, Amira Mohamed, Nicholas J. Johnson, Vasisht Srinivasan, Jay S. Steingrub, Ithan D. Peltan, Samuel M. Brown, Emily T. Martin, Arnold S. Monto, Akram Khan, Catherine L. Hough, Laurence W. Busse, Abhijit Duggal, Jennifer G. Wilson, Nida Qadir, Steven Y. Chang, Christopher Mallow, Carolina Rivas, Hilary M. Babcock, Jennie H. Kwon, Matthew C. Exline, Mena Botros, Adam S. Lauring, Nathan I. Shapiro, Natasha Halasa, James D. Chappell, Carlos G. Grijalva, Todd W. Rice, Ian D. Jones, William B. Stubblefield, Adrienne Baughman, Kelsey N. Womack, Jillian P. Rhoads, Christopher J. Lindsell, Kimberly W. Hart, Yuwei Zhu, Eric A. Naioti, Katherine Adams, Nathaniel M. Lewis, Diya Surie, Meredith L. McMorrow, Wesley H. Self, Nicole Calhoun, Kempapura Murthy, Judy Herrick, Amanda McKillop, Eric Hoffman, Martha Zayed, Michael Smith, Ryan Kindle, Lori-Ann Kozikowski, Lesley De Souza, Scott Ouellette, Sherell Thornton-Thompson, Omar Mehkri, Kiran Ashok, Susan Gole, Alexander King, Bryan Poynter, Caitlin ten Lohuis, Nicholas Stanley, Audrey Hendrickson, Sean Caspers, Walker Tordsen, Olivia Kaus, Tyler Scharber, Jeffrey Jorgensen, Robert Bowers, Jennifer King, Valerie Aston, Richard E. Rothman, Harith Ali, Rahul Nair, Sarah Karow, Emily Robart, Paulo Nunes Maldonado, Maryiam Khan, Preston So, Olivia Krol, Jesus Martinez, Zachary Zouyed, Michael Acosta, Reihaneh Bazyarboroujeni, Haeun Jung, Raju Reddy, Richard Zhang, Alexandra Jun Gordon, Joe Levitt, Cynthia Perez, Anita Visweswaran, Jonasel Roque, Sukantha Chandrasekaran, Los Angeles, Trevor Frankel, Los Angeles, Omai Garner, Los Angeles, Jennifer Goff, David Huynh, Kelly Jensen, Conner Driver, Michael Carricato, Ian Chambers, Paul Nassar, Lori Stout, Zita Sibenaller, Alicia Walter, Jasmine Mares, Spenser Pfannenstiel, Hayley Gershengorn, EJ McSpadden, Rachel Truscon, Lara Thomas, Ramsay Bielak, Weronika Damek Valvano, Rebecca Fong, William J. Fitzsimmons, Christopher Blair, Julie Gilbert, Christine D. Crider, Kyle A. Steinbock, Thomas C. Paulson, Layla A. Anderson, Christy Kampe, Jakea Johnson, Laura L. Short, Lauren J. Ezzell, Margaret E. Whitsett, Rendie E. McHenry, Samarian J. Hargrave, Marica Blair, Jennifer L. Luther, Claudia Guevara Pulido, Bryan P. M. Peterson, Mary LaRose, Leigha Landreth, Madeline Hicks, Lisa Parks, Jahnavi Bongu, David McDonald, Candice Cass, Sondra Seiler, David Park, Tiffany Hink, Meghan Wallace, Carey-Ann Burnham, Olivia G. Arter
Journal: MMWR Morbidity and Mortality Weekly Report (2022)

COVID-19 mRNA vaccines (BNT162b2 [Pfizer-BioNTech] and mRNA-1273 [Moderna]) provide protection against infection with SARS-CoV-2, the virus that causes COVID-19, and are highly effective against COVID-19-associated hospitalization among eligible persons who receive 2 doses (1,2). However, vaccine effectiveness (VE) among persons with immunocompromising conditions* is lower than that among immunocompetent persons (2), and VE declines after several months among all persons (3). On August 12, 2021, the Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for a third mRNA vaccine dose as part of a primary series ≥28 days after dose 2 for persons aged ≥12 years with immunocompromising conditions, and, on November 19, 2021, as a booster dose for all adults aged ≥18 years at least 6 months after dose 2, changed to ≥5 months after dose 2 on January 3, 2022 (4,5,6). Among 2,952 adults (including 1,385 COVID-19 case-patients and 1,567 COVID-19-negative controls) hospitalized at 21 U.S. hospitals during August 19-December 15, 2021, effectiveness of mRNA vaccines against COVID-19-associated hospitalization was compared between adults eligible for but who had not received a third vaccine dose (1,251) and vaccine-eligible adults who received a third dose ≥7 days before illness onset (312). Among 1,875 adults without immunocompromising conditions (including 1,065 [57%] unvaccinated, 679 [36%] 2-dose recipients, and 131 [7%] 3-dose [booster] recipients), VE against COVID-19 hospitalization was higher among those who received a booster dose (97%; 95% CI = 95%-99%) compared with that among 2-dose recipients (82%; 95% CI = 77%-86%) (p <0.001). Among 1,077 adults with immunocompromising conditions (including 324 [30%] unvaccinated, 572 [53%] 2-dose recipients, and 181 [17%] 3-dose recipients), VE was higher among those who received a third dose to complete a primary series (88%; 95% CI = 81%-93%) compared with 2-dose recipients (69%; 95% CI = 57%-78%) (p <0.001). Administration of a third COVID-19 mRNA vaccine dose as part of a primary series among immunocompromised adults, or as a booster dose among immunocompetent adults, provides improved protection against COVID-19-associated hospitalization.