Danger always is lurking at the Olympic door. Mexico’s government troops gunning down protesters days before the Opening Ceremonies in 1968. The Palestinian attack on the Israeli team compound in 1972. Massive debt for Montreal in 1976. Politically engineered boycotts in both 1980 and ’84. A deadly bomb during the Atlanta Games in 1996. Salt Lake City’s post-9/11 jitters in 2002. Fears of oppressive Chinese Communist censorship in 2008. Brazil’s mosquito-borne Zika virus in 2016.

The sky forever seems to be falling. With buttoned-up security, the Olympics go on—and with a remarkable ability to create a festive, peaceful island in an increasingly chaotic world. Not since 1940 and 1944, during World War II, have the Games been cancelled.

But what about this summer’s Tokyo Olympics as the coronavirus radiates from its outbreak in China, across Asia and now into Western nations? The Olympics not only is a hothouse for public dissent (because it is such a visible stage) but also for germs (because so many people, from everywhere, are packed together for three weeks with not enough rest and too much contact). Personal experience: Head colds and viral infections marched through the press facilities at all of the 11 Olympics I covered.

So far, Tokyo officials, who estimate welcoming 11,000 athletes and 600,000 overseas visitors, are insisting there is no Plan B—no thought of calling off, postponing or moving the Games. That, despite news that pre-Olympic qualifying events already have been moved out of China and other Asian venues, affecting athletes from several countries. Quarantines of potential Chinese Olympians have forced disruption of those athletes’ training or cancelled their pre-Olympic competitions. Schooling planned in Japan for 80,000 unpaid Olympic volunteers, hailing from around the world, has been delayed.

Japan already has the highest number of confirmed coronavirus cases outside of China, and the March 1 Tokyo Marathon, which normally has more than 30,000 mostly-amateur runners from home and abroad, will restrict its field to roughly 200 elite professionals. Possibly all wearing surgical masks.

The coronavirus reportedly is related to SARS, the deadly severe acute respiratory syndrome which broke out in China in late 2002. That contagion forced the relocation of the 2003 women’s soccer World Cup, a high-profile 16-nation tournament that had been scheduled for four sites in China, to six cities in the United States.

The move worked, in part because of the Americans’ experience in hosting the previous World Cup four years earlier. So now Shaun Bailey, a London mayoral candidate, has suggested the 2020 Olympics likewise be transferred to his city, which staged the 2012 Games.

Except there is a marked difference between transporting a one-sport championship tournament and the massive Olympic show, with its 33 sports and 30 times the number of participants. Organizing the Olympics, a 1996 Atlanta official said at the time, amounted to “putting on a Super Bowl every day for 17 consecutive days.”

In fact, it is bigger than that. And getting bigger all the time. For Tokyo, 7.8 million tickets have been sold. More than $3 billion in local sponsorship deals have been finalized. NBC has paid $1.4 billion just for U.S. broadcasting rights (with the significant expectation that the Games will fit into its summer programming window before American football and baseball playoffs take over). More than 80,000 hotel rooms are in the mix. Organizers have spent about $25 billion on their Olympic operation.

For obvious reasons, Tokyo wants—and needs—to stick to its schedule. And the history of Olympic perseverance, in the face of multiple challenges, is exceptional. But the 2020 prognosis is iffy.