Comparative Effectiveness and Antibody Responses to Moderna and Pfizer-BioNTech COVID-19 Vaccines among Hospitalized Veterans — Five Veterans Affairs Medical Centers, United States, February 1–September 30, 2021
Authors: Kristina L. Bajema, Rebecca M. Dahl, Steve L. Evener, Mila M. Prill, Maria C. Rodriguez-Barradas, Vincent C. Marconi, David O. Beenhouwer, Mark Holodniy, Cynthia Lucero-Obusan, Sheldon T. Brown, Maraia Tremarelli, Monica Epperson, Lisa Mills, So Hee Park, Gilberto Rivera-Dominguez, Rosalba Gomez Morones, Ghazal Ahmadi-Izadi, Rijalda Deovic, Chad Mendoza, Chan Jeong, Stephanie J. Schrag, Elissa Meites, Aron J. Hall, Miwako Kobayashi, Meredith McMorrow, Jennifer R. Verani, Natalie J. Thornburg, Diya Surie, Joy Burnette, Gustavo Capo, Lauren Epstein, Julia Gallini, Telisha Harrison, Amy Hartley, Liliana Hernandez, Elena Morales, Nina Patel, Kim Rooney, Tehquin Tanner, Ernest Tate, Ashley Tunson, Alexis Whitmire, Juton Winston, Katherine Elliot, Ilda Graham, Diki Lama, Ismael Pena, Adrienne Perea, Guerry Anabelle Perez, Johane Simelane, Sarah Smith, Gabriela Tallin, Amelia Tisi, Alonso Arellano Lopez, Miguel Covarrubias Gonzalez, Bashir Lengi, Mariana Vanoye Tamez, Babak Aryanfar, Ian Lee-Chang, Anthony Matolek, Aleksandra Poteshkina, Saadia Naeem, Evan Goldin, Madhuri Agrawal, Jessica Lopez, Theresa Peters, Geliya Kudryavtseva, Jordan Cates, Anita Kambhampati
Journal: MMWR Morbidity and Mortality Weekly Report (2021)

The mRNA COVID-19 vaccines (Moderna and Pfizer-BioNTech) provide strong protection against severe COVID-19, including hospitalization, for at least several months after receipt of the second dose (1,2).However, studies examining immune responses and differences in protection against COVID-19-associated hospitalization in real-world settings, including by vaccine product, are limited.To understand how vaccine effectiveness (VE) might change with time, CDC and collaborators assessed the comparative effectiveness of Moderna and Pfizer-BioNTech vaccines in preventing COVID-19-associated hospitalization at two periods (14-119 days and ≥120 days) after receipt of the second vaccine dose among 1,896 U.S. veterans at five Veterans Affairs medical centers (VAMCs) during February 1-September 30, 2021.Among 234 U.S. veterans fully vaccinated with an mRNA COVID-19 vaccine and without evidence of current or prior SARS-CoV-2 infection, serum antibody levels (anti-spike immunoglobulin G [IgG] and anti-receptor binding domain [RBD] IgG) to SARS-CoV-2 were also compared.Adjusted VE 14-119 days following second Moderna vaccine dose was 89.6% (95% CI = 80.1%-94.5%)and after the second Pfizer-BioNTech dose was 86.0% (95% CI = 77.6%-91.3%);at ≥120 days VE was 86.1% (95% CI = 77.7%-91.3%)for Moderna and 75.1% (95% CI = 64.6%-82.4%)for Pfizer-BioNTech.Antibody levels were significantly higher among Moderna recipients than Pfizer-BioNTech recipients across all age groups and periods since vaccination; however, antibody levels among recipients of both products declined between 14-119 days and ≥120 days.These findings from a cohort of older, hospitalized veterans with high prevalences of underlying conditions suggest the importance of booster doses to help maintain long-term protection against severe COVID-19.†