The greatest outcome in Bay Area sports history?

Was it when the 49ers won their first Super Bowl? When the Giants won the 2010 World Series? When the Warriors kicked off their fabulous dynasty six seasons ago with an NBA championship?

Or was it Super Bowl Sunday, when the 49ers blew a fourth-quarter lead and got crushed by the Kansas City Chiefs, and maybe, inadvertently, saved thousands of lives?

San Francisco and California have led the nation in coronavirus response. We have shown how to flatten the deadly curve. Much of that is a credit to the gutsy and intelligent leadership of Mayor London Breed, Gov. Gavin Newsom and our medical community. But there is also an element of luck that sure didn’t feel like it at the time.

Dr. Niraj Sehgal is head of UCSF’s COVID-19 Command Center. In a recent video town hall, Sehgal talked about UCSF and the city being Ground Zero for coronavirus response, and he presented a chilling scenario.

“People may not remember this that well,” Sehgal said, “but (on) Super Bowl weekend, in some ways, with apologies to the 49ers’ fans, the gift we may have been given was the 49ers losing.

“If you think about what happened that weekend, had the 49ers won, and there were parades, and parties at that time, that may have had impact that I haven’t seen actually described.”

Let’s describe it, then.

Thousands of fans would have met their conquering heroes Monday afternoon when the 49ers’ plane touched down from Miami. Bars and restaurants all over the Bay Area would have been jammed with celebrants. Parties galore. Wednesday, the parade down Market Street! A million-plus fans jammed along the route, some sitting on shoulders to glimpse their heroes.

In sum, a wonderful crush of happy humanity — and a Disneyland for the coronavirus. We would have been social distancing like sardines.

Remember, these were innocent times. We knew the virus was out there lurking, but it was a distant threat, a mild concern. We didn’t realize that it was among us, looking for an opportunity to flourish.

Our guard was down. Toilet paper was plentiful. Fear was for wimps. We still went to basketball games and concerts, crowding together, but nothing like what would have occurred had the 49ers won.

The NBA shut down on March 11. San Francisco shut down March 16, under Breed’s order. Newsom’s stay-at-home orders followed three days later. The Super Bowl was Feb. 2.

“It’s a date that I will never forget,” Sehgal said, “because the Super Bowl Sunday was actually the night that we stood up formally, our command center. And the reason for that is another — again, it’s funny to call it a gift — the gift that we had, two of the first patients in the country that required hospitalization.

“They arrived in the middle of the night, I will never forget sitting in that ambulance bay when those first two patients rolled up, a husband and wife who looked terrified because of everything around them. And it also forced our organization to kind of, we were in the game quickly and within five days we became the regional and national experts on how to do this, because everyone else was three to five days behind us.”

So UCSF’s reaction was spectacular, and became the national model, a literal life-saver.

But what if we had given the virus that parade and all that social un-distancing? Like giving Michael Jordan a pogo stick.

The old expression is, “I’d rather be lucky than good.” The Bay Area has been both.

And the 49ers’ Super Bowl loss? Now, it doesn’t seem quite so disastrous.

Scott Ostler is a columnist for the San Francisco Chronicle. Email: sostler@sfchronicle.com Twitter: @scottostler