UCI Health study in JAMA Networks finds COVID-19 vaccination reduced infection rates among healthcare personnel

Study confirms effectiveness of the vaccine amid high community infection rates

July 09, 2021

A new study published in JAMA Network saw a reduction of COVID-19 infection rates among healthcare personnel at UCI Health after receiving the COVID-19 vaccine.

By mid-April, there were 133 million COVID-19 cases and 2.9 million associated deaths worldwide. Concerns over asymptomatic infection and transmission risks in vaccinated individuals prompted UCI Health physicians to conduct a quality improvement study, to see if symptomatic and asymptomatic infections decreased in healthcare personnel (HCP) after receiving the COVID-19 vaccine.

“Vaccines exist to curb disease transmission – yet there was a lot of skepticism around whether COVID-19 vaccination would be effective against silent spreaders of the disease,” says Dr. Shruti Gohil, UCI Health associate medical director for epidemiology and infection prevention. “We were able to dispel these rumors and show the vaccine’s effectiveness in decreasing both symptomatic and asymptomatic infections.”

The 15-week study, which began in November 2020, evaluated COVID-19 cases among UCI Health workers before and after receiving the vaccine. All UCI Health HCP were screened daily for COVID-19 symptoms, including a temperature check. Those who were experiencing COVID-19 related symptoms were administered a rapid COVID-19 test and random testing was done on those who didn’t display any symptoms.

The study confirmed the effectiveness of the vaccine even during a time when infection rates in the community were high.

During the winter surge, HCP COVID-19 cases paralleled the countywide prevalence, but decreased a week after second vaccine doses were initiated. After second doses began, daily HCP cases fell from 18 to 8 (55% reduction) after one week; to 3 (84% reduction) after two weeks, and to 1 (94% reduction) three weeks after receiving the vaccine.

A rapid and sustained decline in both COVID-19 symptomatic and asymptomatic infections was seen following HCP vaccination in a region experiencing high rates of COVID-19 disease nationally in the 2020-21 winter season.

This is the second UCI Health clinical study published this year in JAMA Network relating to COVID-19. “Outcomes and Mortality Among Adults Hospitalized with COVID-19 at US Medical Centers,” published March 5, examined COVID-19 outcomes and mortality among hospitalized adults. The largest such study to date examined the characteristics the outcomes of more than 192,000 hospitalized adults with COVID-19 utilizing data from 47 states.

UCI Health is the clinical enterprise of the University of California, Irvine. Patients can access UCI Health at primary and specialty care offices across Orange County and at its main campus, UCI Medical Center in Orange, Calif. The 418-bed acute care hospital, listed among America’s Best Hospitals by U.S. News & World Report for the 20th consecutive year, provides tertiary and quaternary care, ambulatory and specialty medical clinics, and behavioral health and rehabilitation services. UCI Medical Center is home to Orange County’s only National Cancer Institute-designated comprehensive cancer centerhigh-risk perinatal/neonatal program and American College of Surgeons-verified Level I adult and Level II pediatric trauma center and regional burn center. UCI Health serves a region of nearly 4 million people in Orange County, western Riverside County and southeast Los Angeles County. Follow us on Facebook and Twitter.

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