CHICAGO (CBS) — The University of Chicago Medical Center on Thursday announced that it is moving to requiring masks for all staff as it takes on the next stages of the battle against coronavirus.

Beginning Friday, the academic health system at the U of C will transition all staff to wearing masks as it brings back asymptomatic faculty and staff who had to be quarantined after exposure to the virus.

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Under the new rule, all personnel – clinical or otherwise – must wear some type of face mask while working on the medical campus.

The goal is to reduce the risk of transmission from staff who might be carrying the disease, but might be asymptomatic.

Anyone who has respiratory systems, flu-like illness, or a fever will not return to work, and those who have tested positive for COVID-19 must stay home until cleared to return.

In accordance with the masking policy, the medical center noted that U of C Medical Center health care workers will use N95 respirators and surgical masks depending on what kind of patient care is involved.

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The tight-fitting N95 respirators are the most effective kind, in which all air goes through the material of the mask. They remove 95% of particles, U of C epidemiologist Dr. Emily Landon said.

Surgical masks have wire on top and paper ear ties, which are not as tight, but are effective against droplets.

The Centers for Disease Control and Prevention has also advised cloth masks are an effective alternative during crisis situations.

If cloth masks are in short supply, employees will be issued a procedural mask and will receive a cloth version once supplies are replenished, the hospital said.

Meanwhile as to staffing issues, Landon said the U of C Medical Center is trying not to use medical students or promote them ahead of time – on the grounds that it is not appropriate for them to see patients with COVID-19. The hospital also has not asked for retired workers because they are at higher risk for complications, Landon said.

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In a press briefing late Thursday, Landon said there are 50 people who have tested positive for COVID-19 at the hospital and 70 more under observation. She said the number is probably climbing.