April 30, 2021

A new report from the Centers for Disease Control and Prevention (CDC) and academic researchers has found that COVID-19 vaccines are 94% effective at preventing hospitalization for COVID-19.

The findings are among the first to demonstrate high effectiveness of COVID-19 vaccines in the U.S. population of older adults, and included data collected from January 2021 through March 2021. The study evaluated the Pfizer/BioNTech and Moderna vaccines, the most commonly used during the study period.

Led by researchers at the CDC and Vanderbilt University Medical Center, the study examined 417 hospitalized patients from a large network of 24 hospitals across 14 states. Study findings were published in Morbidity and Mortality Weekly Report.

“These findings indicate that vaccination is very effective in reducing the risk of hospitalization with COVID-19 in older adults, a highly vulnerable population that was severely affected during the earlier periods of the pandemic. The study examined the effects of vaccination as they occur in the communities, so that these results complement earlier data from manufacturers’ experimental clinical trials” said Dr. Carlos Grijalva, MD MPH, associate professor in the Division of Pharmacoepidemiology in the Department of Health Policy at VUMC, and one of the researchers who authored the study.

carlos grijalva md mph

These are very encouraging observations and should be considered by individuals who did not feel ready for vaccination before, Grijalva said. COVID-19 vaccinations are now available to all U.S. adults, and are offered through a wide array of local pharmacies, grocery stores, hospitals and health departments.

“These data suggest that continuing to rapidly vaccinate U.S. adults against COVID-19 will likely have a marked impact on COVID-19 hospitalizations and to lead to reductions in post-COVID sequalae and deaths,” said Dr. Wesley Self, MD, MPH, associate professor of Emergency Medicine and Vice President for Clinical Research Networks and Strategy at VUMC, who is leading the national network studying COVID vaccine effectiveness. “As the pandemic continues evolving, it will be crucial to continue monitoring the effectiveness of vaccines.”

This research was conducted by two CDC-supported networks — the Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) and the Influenza and Other Viruses in the Acutely Ill (IVY) Network, which is a national research collaborative supported by the CDC and coordinated by VUMC under the leadership of Self. Other Vanderbilt investigators who participated in the report include, Keipp Talbot, MD, MPH; Todd Rice, MD, MSc; Christopher Lindsell, PhD; Ian Jones, MD; Bo Stubblefield, MD; Jon Casey, MD, MSCI; Yuwei Zhu, MD MSc; Dayna Wyatt RN; Kelsey Womack PhD, Adrienne Baughman and Kimberly Hart.