Study: Risk of catching COVID-19 during hospital stay remains low

Editor's Note

A new Cosmos study by Epic Research finds that cases of “hospital-developed COVID-19”—or patients who were admitted to the hospital free of infection but acquired COVID-19 during their hospital stay—are low, the American Hospital Association reported February 7. According to the study, only about 1.8% of patients admitted are cases of hospital-developed COVID-19, equating to some 172 patients at the highest peak of infection in December 2020.

Cosmos is a HIPAA-defined limited data set of more than 126 million patients from 156 Epic organizations. This study was completed by two teams, who worked independently and came to similar conclusions.

The study looks at patients who tested negative on the day of, or the day after, admission and then tested positive 6 or more days post-admission. “We chose this timeframe to try and exclude patients who might have been positive on admission but tested negative at the time,” the researchers explain. Positive COVID-19 tests or diagnoses within 90 days prior to admission were also excluded from the data pool.

The study also finds that in the last half of 2021, the rate of patients who tested negative and then positive after hospital admission rose about half as much as overall COVID-19 admissions. “We speculate that increased vaccination rates among hospital staff, patients, and visitors have contributed to a further limiting of the spread of COVID-19,” the researchers say.