What happened 

Cruise ship stocks rose on Monday as investors apparently grew less concerned about soaring COVID-19 case counts in the U.S. and around the world.

By the close of trading, shares of Royal Caribbean (NYSE:RCL) and Norwegian Cruise Line Holdings (NYSE:NCLH) were both up 8.4%, while Carnival's two stocks Carnival Corporation (NYSE:CCL) and Carnival plc (NYSE:CUK) were up 6.3% and 2.9%. 

So what 

Even as the number of new coronavirus infections surged in many parts of the world, investors bid up shares of COVID-19-sensitive cruise ship companies. Some analysts, such as Tom Lee of Fundstrat Global Advisors, are apparently focusing on reports that the number of people who are dying from COVID-19 is not rising as quickly as the number of people who are getting sick from the disease. "While there were many alarming COVID-19 'headlines' over the weekend, noting 'record case' numbers, daily U.S. deaths attributed to COVID-19 fell to a new low of 253," Lee said. 

Three cruise ships are docked at port.

Cruise ship stocks rebounded on Monday. Image source: Getty Images.

While a decreasing coronavirus death rate is certainly good news, it's not enough to wave the all-clear sign for the cruise ship industry. Texas, Florida, California, and Washington are slowing and even reversing their reopening plans as the virus rips through their states, and other states may be forced to follow suit. If that happens, health authorities are unlikely to lift sailing restrictions on the major cruise ship operators.

Now what

A continued decline in the COVID-19 fatality rate would of course be welcomed news. But investors shouldn't forget that the disease has already killed more than 500,000 people globally and sickened millions. The threat the coronavirus poses to the cruise industry -- and to humanity, for that matter -- should not be dismissed.

Until an effective vaccine or treatment for COVID-19 is developed, an investment in Royal Caribbean, Carnival, or Norwegian Cruise Line Holdings remains fraught with risk.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.