More than a week has passed since Lyndsay Harrington has heard from her brother, who is locked up at a federal prison in California that houses inmates with health problems.

“We’re just so scared,” Harrington said. She has good reason to worry.

Some 600 inmates at FCI Terminal Island, roughly 57 percent of the total inmate population, have tested positive for the coronavirus, officials said. Five inmates have died after contracting COVID-19, including three in the last 48 hours, and at least 10 staff members have been infected.

Harrington said her brother is particularly vulnerable because he suffers from asthma and a thyroid condition.

“We don’t want this to turn into a death sentence for him,” she said of her brother, who is also bipolar.

Like others interviewed for this story, Harrington asked that her sibling not be named because her family fears prison staffers could retaliate against him.