The aircraft carrier USS Theodore Roosevelt will head back out to sea this week, the Navy says, almost two months after docking in Guam to deal with a serious Covid-19 coronavirus outbreak. Worrisome questions remain.

The ship will operate for a time with a minimal crew of about 3,000; another 1,800 sailors must remain behind in quarantine for now, reports the Associated Press. More than half of those 1,800 previously tested positive.

Those still quarantined include 14 sailors who seem to have been infected twice, which surprised medical experts.

Those 14 had tested positive for the virus, waited it out in isolation on land, returned to the ship after twice testing negative — and then tested positive again. They and some 30 others who came in direct contact with them returned to quarantine.

“The puzzling Covid-19 reappearance in the sailors adds to the difficulty in getting the ship’s crew healthy again, and fuels questions about the quality of the testing and just how long sailors may remain infected or contagious,” the AP says.

It also raises chilling questions for all Americans and the entire world:

• Will intensive testing truly help contain the spread of the virus?

• Are the current testing techniques sufficient, or accurate?

• Can the coronavirus re-infect a seemingly recovered Covid-19 patient?

In any event, the now thoroughly cleaned Roosevelt will once again become a kind of test-bed for understanding the virus and how best to deal with it when close quarters can’t be avoided, making social distancing impossible.

The ship’s current commander, Capt. Carlos Sardiello, told the AP in a phone interview that while he can’t predict the future — “Do I have a crystal ball? I do not,” he said — he has “set the conditions for a high probability of success, and we’re going to go to sea and do our mission.”

Sardiello wouldn’t describe that mission.

But unnamed U.S. officials told the AP it will “conduct carrier qualifications for the flight-deck crew, including fighter jet takeoffs and landings. After about two weeks, the carrier [will] return to Guam to pick up healthy sailors” and return to sea.”

Eventually, the ship will return to its home base in San Diego.

What might happen between now and then is the biggest question of all.