New study finds COVID-19 vaccines are highly effective in preventing hospitalizations

Posted at 5:24 AM, Oct 29, 2021

Researchers from Intermountain Healthcare played a major role in a vital new study that adds further evidence that COVID-19 vaccines are highly effective in helping people stay out of the hospital, including the ICU and emergency department.

The national multi-center study of more than 100,000 patients, just published in the New England Journal of Medicine, was conducted by researchers from some of the nation’s leading health systems, including those from Intermountain Healthcare.

Researchers say the study further demonstrates the real-world safety and effectiveness of the vaccines.

“Not only were COVID vaccines found to be effective in clinical trials, but now we’re getting very robust, real-world evidence of how these vaccines are working in our communities across the United States,” said Eddie Stenehjem, MD, Intermountain Healthcare infectious diseases physician and a researcher.

“We’re seeing consistent findings, and remarkable evidence, that COVID-19 vaccines are effective in preventing the need for hospitalization, and for emergency and urgent care visits.”

As part of the CDC’s VISION Network, a nationwide consortium of healthcare networks, researchers from Intermountain and other centers, examined patient electronic health records from January 1 to June 22, 2021. This study was limited to patients 50 years of age or greater.

In data drawn from more than 41,000 hospitalizations and 21,000 emergency department or urgent care visits from 187 hospitals and 221 emergency departments and urgent care clinics from across the country, including those at Intermountain Healthcare, researchers found COVID vaccines to be highly effective.

Researchers found that the Pfizer-BioNTech or Moderna mRNA vaccines were 91% effective in preventing emergency department/urgent care encounters, 88% effective in preventing hospitalizations, and 90% effective in preventing the need for ICU care, in patients fully vaccinated (14 days past their 2nd shot).

The researchers also found that the Johnson&Johnson vaccine, which requires one shot, was 73% effective in preventing emergency department/urgent care encounters and 68% effective in preventing hospitalizations

Since this study was conducted, the more contagious Delta variant has become the dominant strain of COVID-19 in the U.S.

Subsequent data collected from this same cohort from June through August 2021 found that some vaccines are becoming less effective over time as reported in the DC’s Morbidity and Mortality Weekly Report today.

Analyzing the data in a similar fashion, investigators found that during the period that the Delta variant was dominant, the Moderna vaccine remained extremely effective at preventing hospitalizations (95% efficacy), but the Pfizer Vaccine had decreased in effectiveness (80%), as had J&J (60%). Similarly, the effectiveness of the Moderna vaccine preventing ED/UC visits remained stable at 92%, while Pfizer declined to 77% and J&J declined to 65%.

This reduction in effectiveness in the Pfizer and J&J vaccines is possibly due to waning immunity over time and due to changes from the delta variant speculates Dr. Eddie Stenehjem, Intermountain Healthcare infectious diseases physician and a co-author of the study.

“The goal of any vaccine is to keep you alive and out of the hospital,” Dr. Stenehjem added. “Even though we’re seeing that vaccines lose some effectiveness over time, they are still extremely powerful tools in fighting this deadly virus and keeping people out of the hospital.”

Dr. Stenehjem says that this is most likely due to a combination of the Delta variant being more transmissible, and vaccines becoming less effective over time, which is not uncommon.

“It’s why we get a tetanus booster every 10 years, and a flu shot every year, and why we’re already giving booster shot to immunocompromised people, and most likely will be giving everyone booster shots in the future.”

Researchers say these results are incredibly encouraging and demonstrate that our vaccines remain incredibly effective against the SARS CoV 2 Delta variant.

“Vaccines are a powerful line of defense against this terrible virus. They are safe, effective, widely available, and free,” said Dr. Stenehjem.

Other participating networks/systems in the study include Columbia University Irving Medical Center (CUIMC; New York); HealthPartners Institute (Minnesota and Wisconsin); Intermountain Healthcare (Utah); Kaiser Permanente Northern California (KPNC); Kaiser Permanente Northwest Center for Health Research (Oregon and Washington); Regenstrief Institute (Indiana), and the University of Colorado.