UChicago Medicine Study Challenges CDC Recommendations

While the CDC recommends returning to work after five days, the study claims that's when the virus is at its peak.

New data from a study by the University of Chicago Medicine is showing that 40% of vaccinated healthcare workers are still testing positive for COVID-19 up to 10 days after their symptoms began.

The study, which has not yet been peer reviewed, followed the U.S. Centers for Disease Control and Prevention's (CDC) isolation recommendations from January, saying individuals with COVID-19 could end their isolation after five days if they were fever free, their symptoms were beginning to go away, or if they were no longer experiencing symptoms.

Even more individuals with COVID-19 may still be contagious after the first few days, including those who feel like they've recovered, the study said.

While the CDC didn't recommend getting tested again after the fifth day of isolation, having individuals return to work before 10 days of isolation or receiving a negative rapid antigen test to be certain they're no longer sick could increase the likelihood of others getting sick.

 The CDC's isolation recommendations were based on studies done prior to the omicron variant, as well as before people got vaccinated or infected, according to Emily Landon, MD, executive medical director of Infection Prevention and Control at the University of Chicago who co-authored the study.

"In those situations, symptoms generally didn't start until a person had already reached their peak virus load," she said. "In those cases, ending isolation after five days might be reasonable, since earlier data showed few people still had live virus at that point."

With the omicron variant, Landon added, symptoms are showing up before the peak virus load, so an individual's isolation period begins earlier. However, those individuals are more contagious after the sixth day, she said.

After discussions with public health and infectious disease experts, UChicago Medicine developed a policy that would allow fully vaccinated healthcare workers with mild symptoms to return to work after five days of isolation. However, the employees would be required to take a rapid antigen test as a precaution.

Those able to return early had to follow strict masking and distancing guidelines. Employees with negative results wouldn't be able to return to work until either testing negative or after day 11 of isolation.

The  study has implications for the CDC's recent return-to-work recommendations, the research team said. One hypothesis that came from the study is that individuals who'd been vaccinated and gotten a booster shot were  more likely to have a positive rapid antigen test on their first attempt to return to work. The same individuals may also get better before the virus is out of their system.

While the health system encouraged the use of rapid antigen testing before ending isolation and returning to work, it emphasized that preventive measures like masking are also important.

"Without checking a rapid test to be sure your viral load is past its peak, ending isolation early may increase the risk of infecting others," Rachel Marrs, DNP, RN, and director of Infection Control and Prevention at UChicago Medicine said. "That would counteract the hope that ending isolation early would reduce the staffing issues plaguing nearly every industry."