Latest booster reduces adults’ risk of moderate or severe COVID by more than half

The most recent COVID-19 booster shot reduces adults’ risk of moderate or severe COVID by more than half, according to a new nationwide data study from September 2023 through January 2024, a period of JN.1 variant dominance.

The new study is one of the first to evaluate protection provided by the updated shot against COVID-19-associated emergency department and urgent care visits (markers for moderate disease) and against hospitalizations (a marker for severe disease), in individuals 18 and older, due to JN.1, the most recently predominant strain of COVID.

“Halving your risk of needing to visit an E.D. or urgent care center or to be treated in the hospital for COVID is significant,” said study co-author Shaun Grannis, M.D., M.S., Regenstrief Institute vice president for data and analytics and a professor at Indiana University School of Medicine. “As an informatician I want to highlight that the data we analyzed came from different populations and geographic locations, adults of all ages and the most recent COVID strain. This analysis strongly supports the benefit of getting a booster shot and as a clinician, I encourage my patients to do so.”

“These are encouraging findings,” said study co-author Brian Dixon, PhD, MPA, interim director of Regenstrief Institute’s Clem McDonald Center for Biomedical Informatics and professor at Indiana University Richard M. Fairbanks School of Public Health. “These estimates of vaccine effectiveness are what we would expect for an annual booster designed for an endemic virus that continues to evolve. We looked at a longer time period than similar studies in Europe, and we found good performance. Yet we do need to be alert to the presumed waning of the updated booster’s effectiveness, which we have seen in earlier COVID-19 vaccines. Americans should expect the CDC to recommend future boosters, likely on an annual schedule.”

These findings of protection against moderate and severe disease provided by the booster in this large study are consistent with those of an earlier, small scale study of individuals seen for testing at a pharmacy. That study did not include hospitalized patients.

The authors of the new study, co-authored by Drs. Grannis and Dixon, concluded, “In this analysis of updated COVID-19 VE [vaccine effectiveness], receipt of an updated COVID-19 vaccine dose provided protection against COVID-19-associated ED/UC [emergency department/critical care] visits and hospitalizations among immunocompetent adults. CDC will continue monitoring VE of updated COVID-19 vaccines. All adults should stay up to date with recommended COVID-19 vaccines, including receiving a dose of updated vaccine.”

“Interim Effectiveness of Updated 2023–2024 (Monovalent XBB.1.5) COVID-19 Vaccines Against COVID-19–Associated Emergency Department and Urgent Care Encounters and Hospitalization Among Immunocompetent Adults Aged ≥18 Years — VISION and IVY Networks, September 2023–January 2024” is published in Morbidity and Mortality Report (MMWR). The study was funded by the CDC.

All authors and affiliations

Jennifer DeCuir, MD, PhD¹; Amanda B. Payne, PhD¹; Wesley H. Self, MD²; Elizabeth A.K. Rowley, DrPH³; Kristin Dascomb, MD, PhD⁴; Malini B. DeSilva, MD⁵; Stephanie A. Irving, MHS⁶; Shaun J. Grannis, MD^7,8; Toan C. Ong, PhD⁹; Nicola P. Klein, MD, PhD¹⁰; Zachary A. Weber, PhD³; Sarah E. Reese, PhD³; Sarah W. Ball, ScD³; Michelle A. Barron⁹; Allison L. Naleway, PhD⁶; Brian E. Dixon, PhD^8,39; Inih Essien, OD⁵; Daniel Bride, MS⁴; Karthik Natarajan, PhD^11,12; Bruce Fireman¹⁰; Ami B. Shah, MPH^1,13; Erica Okwuazi, MSc^1,13; Ryan Wiegand, PhD¹; Yuwei Zhu, MD²; Adam S. Lauring, MD, PhD¹⁴; Emily T. Martin, PhD¹⁴; Manjusha Gaglani, MBBS^15,16; Ithan D. Peltan, MD^17,18; Samuel M. Brown, MD^17,18; Adit A. Ginde, MD⁹; Nicholas M. Mohr, MD¹⁹; Kevin W. Gibbs, MD²⁰; David N. Hager, MD, PhD²¹; Matthew Prekker, MD²²; Amira Mohamed, MD²³; Vasisht Srinivasan, MD²⁴; Jay S. Steingrub, MD²⁵; Akram Khan, MD²⁶; Laurence W. Busse, MD²⁷; Abhijit Duggal, MD²⁸; Jennifer G. Wilson, MD²⁹; Steven Y. Chang, MD, PhD³⁰; Christopher Mallow, MD³¹; Jennie H. Kwon, DO³²; Matthew C. Exline, MD³³; Cristie Columbus, MD^15,34; Ivana A. Vaughn, PhD³⁵; Basmah Safdar, MD³⁶; Jarrod M. Mosier, MD³⁷; Estelle S. Harris, MD¹⁸; Jonathan D. Casey, MD²; James D. Chappell, MD, PhD²; Carlos G. Grijalva, MD²; Sydney A. Swan²; Cassandra Johnson, MS²; Nathaniel M. Lewis, PhD³⁸; Sascha Ellington, PhD³⁸; Katherine Adams, MPH³⁸; Mark W. Tenforde, MD, PhD³⁸; Clinton R. Paden, PhD¹; Fatimah S. Dawood, MD¹; Katherine E. Fleming-Dutra, MD¹; Diya Surie, MD¹; Ruth Link-Gelles, PhD¹; CDC COVID-19 Vaccine Effectiveness Collaborators

¹Coronavirus and Other Respiratory Viruses Division, National Center for Immunization and Respiratory Diseases, CDC; ²Vanderbilt University Medical Center, Nashville, Tennessee; ³Westat, Rockville, Maryland; ⁴Division of Infectious Diseases and Clinical Epidemiology, Intermountain Healthcare, Salt Lake City, Utah; ⁵HealthPartners Institute, Minneapolis, Minnesota; ⁶Kaiser Permanente Center for Health Research, Portland, Oregon; ⁷Indiana University School of Medicine, Indianapolis, Indiana; ⁸Regenstrief Institute Center for Biomedical Informatics, Indianapolis, Indiana; ⁹University of Colorado School of Medicine, Aurora, Colorado; ¹⁰Kaiser Permanente Vaccine Study Center, Kaiser Permanente Northern California Division of Research, Oakland, California; ¹¹Department of Biomedical Informatics, Columbia University Irving Medical Center, New York, New York; ¹²New York-Presbyterian Hospital, New York, New York; ¹³General Dynamics Information Technology, Falls Church, Virginia; ¹⁴University of Michigan, Ann Arbor, Michigan; ¹⁵Baylor Scott & White Health, Texas; ¹⁶Baylor College of Medicine, Temple, Texas; ¹⁷Intermountain Medical Center, Murray, Utah; ¹⁸University of Utah, Salt Lake City, Utah; ¹⁹University of Iowa, Iowa City, Iowa; ²⁰Wake Forest School of Medicine, Winston-Salem, North Carolina; ²¹Johns Hopkins University School of Medicine, Baltimore, Maryland; ²²Hennepin County Medical Center, Minneapolis, Minnesota; ²³Montefiore Medical Center, Albert Einstein College of Medicine, New York, New York; ²⁴University of Washington, Seattle, Washington; ²⁵Baystate Medical Center, Springfield, Massachusetts; ²⁶Oregon Health & Science University, Portland, Oregon; ²⁷Emory University, Atlanta, Georgia; ²⁸Cleveland Clinic, Cleveland, Ohio; ²⁹Stanford University School of Medicine, Stanford, California; ³⁰Ronald Reagan UCLA Medical Center, Los Angeles, California; ³¹University of Miami, Miami, Florida; ³²Washington University in St. Louis, St. Louis, Missouri; ³³The Ohio State University, Columbus, Ohio; ³⁴Texas A&M University College of Medicine, Dallas, Texas; ³⁵Henry Ford Health, Detroit, Michigan; ³⁶Yale University School of Medicine, New Haven, Connecticut; ³⁷University of Arizona, Tucson, Arizona; ³⁸Influenza Division, National Center for Immunization and Respiratory Diseases, CDC; ³⁹Richard M. Fairbanks School of Public Health at Indiana University-Indianapolis

About Shaun Grannis, M.D., M.S.
In addition to his role as the vice president for data and analytics at Regenstrief Institute, Shaun Grannis, M.D., M.S., holds the Regenstrief Chair in Medical Informatics and is a professor of family medicine at Indiana University School of Medicine.

Brian E. Dixon, PhD, MPA 
In addition to his role as the director of public health informatics at Regenstrief Institute and Indiana University Richard M. Fairbanks School of Public Health at Indiana University-Indianapolis, Brian E. Dixon, PhD, MPA, is the interim director and a research scientist with the Clem McDonald Center for Biomedical Informatics at Regenstrief Institute and an associate professor of epidemiology at Indiana University Fairbanks School of Public Health at IUPUI. He is also an affiliate scientist at the U.S. Department of Veterans Affairs Health Services Research and Development Center for Health Information and Communication, Richard L. Roudebush VA Medical Center.