At 4 p.m. Thursday, just as trading closed on the stock market, the Centers for Disease Control and Prevention (CDC) announced that it has "extended the No Sail Order and Suspension of Further Embarkation" through Sept. 30.

This means, in essence, that no cruise line will be able to sail out of an American port before that date, unless either the Secretary of Health and Human Services declares that COVID-19 no longer constitutes a public health emergency, or the CDC Director otherwise rescinds or modifies the no-sail order based on specific public health or other considerations.

Collage showing a cruise ship, a man in a face mask and a virion.

Image source: Getty Images.

That's the bad news.

The good news is that the major cruise lines, via their industry association Cruise Lines International Association (CLIA), had already announced they would voluntarily extend their own suspension of cruise operations through Sept. 15, 2020.

Because CLIA guessed almost right, and had already extended its own suspension of operations to within two weeks of the date the CDC ultimately settled upon, cruise line stocks seem to be taking the news mostly in stride. As of 10:15 a.m. EDT Friday, shares of cruise stocks Carnival Corporation (CCL 0.99%) (CUK 1.08%) and Royal Caribbean (RCL 2.50%) are both down less than 1%, and Norwegian Cruise Lines (NCLH 0.10%) has been hit only a bit worse -- down 1.6%.

The CDC announced the first no-sail order on March 14, 2020, barring cruise lines from sailing out of American ports. One month later, the CDC extended the effect of this order through at least June 26, then July 24.