The leadership of the USS Theodore Roosevelt failed to put in place measures to stop a coronavirus outbreak on board the aircraft carrier and exacerbated a growing problem by releasing sailors too early from quarantine, a Department of Defense inspector general investigation concluded.

The report, consistent with a deeper investigation into the outbreak in which nearly 20% of the crew tested positive for Covid-19, also found that four out of five Navy component commands did not run a biennial infectious disease exercise that may have helped reduce the spread of the virus.

“USS Theodore Roosevelt leadership did not effectively implement mitigation measures for the majority of their crew,” the report said. Social gathering areas on board the ship remained open, while “non-essential” urine tests for illegal substances continued, the report added. In addition, sailors were released early from quarantine because conditions were crowded, and the ship’s leadership “believed that the quarantine caused more sailors to become infected.”

The commander of the nuclear-powered aircraft carrier, Capt. Brett Crozier, was relieved of command in early April after writing a letter to his superiors warning that action was needed to save the lives of his crew. An initial probe into Crozier’s handling of the outbreak recommended that he be reinstated, but then-Defense Secretary Mark Esper did not immediately accept the recommendation. A more thorough investigation released in June recommended the firing of Crozier, faulting him for improper social distancing and being too slow to evacuate soldiers from the ship once it arrived in port in Guam.

The USS Theodore Roosevelt was one of only two ships to go through a coronavirus outbreak while at sea. The carrier had just finished a port call in Vietnam when the ship’s first case of Covid-19 was diagnosed on March 24. Within weeks, more than 1,000 members of the ship’s 4,900-member crew also tested positive, prompting the Navy to evacuate most of the crew to Guam.

The other ship to go through an outbreak at sea was the USS Kidd, a destroyer carrying out counter-narcotic operations in the eastern Pacific when the first coronavirus case was reported on April 22. Six days later, the destroyer arrived at Naval Base San Diego to receive medical care for the crew.

The Navy has not revealed how many of the ship’s 330-member crew tested positive, but the inspector general report said the USS Theodore Roosevelt and the USS Kidd had the highest number of cases relative to crew size.

In January, approximately a dozen sailors from the destroyer USS Chafee tested positive for the virus, a Navy official said. Those sailors and approximately 40 others were in close contact isolated off the ship in San Diego as the ship’s entire crew was tested.