Americans are in a sprint to return to the sports they love. Players want to play, coaches want to coach, and teams want to see fans in the stands sooner than later. But what if a return to sports (as they once were) winds up being more of a marathon than a sprint?

For months I’ve been covering the race to develop a COVID-19 cure. Though public health officials claim an FDA-approved vaccine should be ready by early 2021, that timeline is based more on medical optimism than scientific evidence or past precedent. Nearly all vaccines take five years or, usually, much longer. The world record for the fastest effective vaccine was set in 1967, when Merck licensed the mumps inoculation in just four years.

Scientists say that reaching “herd immunity,” the point at which the virus will no longer spread, will require at least 50 percent of the country (165 million Americans) to be vaccinated or to acquire the virus and recover from it. This means a vaccine will need to be highly effective and that Americans will need to feel safe taking it. Neither outcome is definite and, regardless, getting there could take several years. Even the most optimistic timeline assumes people will develop long-lasting immunity to the virus, which is also not a given (per here and here and here).

Not to rain on anyone’s Rose Bowl Parade, but the postponement of Big Ten and PAC-12 football won’t be the last sporting casualty of the coronavirus era. With the United States still far from the COVID-19 finish line, here are five huge threats facing the future of sports.

1. The financial threat 

Sports represent the 11th largest industry in the United States, wedged between communications (10) and chemicals (12). With an estimated worth of $750 billion, the games we play are serious business. And that business is in serious trouble.

Major League Baseball is projected to lose several billions during its shortened season—a season that only 49 percent of MLB fans believe will result in the crowning of a World Series champion. The NBA, which is keeping its players locked in an Orlando bubble, expects to lose an estimated $500 million this season in ticket sales alone.

With untold tickets, merchandise, and ad space going unsold, the health of the sports industry is in decline. The question is, how far will it fall? While league commissioners and college presidents scramble to make their 2020-21 seasons work, no one has laid out a plan to make future seasons profitable if stadiums and arenas are forced to remain empty for the next two or three seasons.

2. The medical threat

Athletes who compete at the highest levels tend to be young and in great physical shape. But they’re not invincible.

Eduardo Rodriguez, the Boston Red Sox’s ace pitcher, was diagnosed with COVID-19 on July 7 and was scheduled to return 11 days later. An MRI showed myocarditis (inflammation of the heart), a potentially deadly consequence of the coronavirus. Rodriguez said the symptoms “made me feel like I was 100 years old.” Already, more than a dozen NCAA players have been diagnosed with the same problem.

There’s still a lot scientists don’t know about the lingering health effects of COVID-19. However, early research indicates that problems may include long-term damage to the heart, lungs, kidneys, and brain.

Those most vulnerable, according to The Centers for Disease Control and Prevention (CDC), include people with a body mass index (BMI) above 30. Based on my count, there are more than 300 players on NFL rosters who weigh 300 pounds or more. Although the League hasn’t issued any info about the rate of infection, the players’ union announced 95 positive tests back in July.

Though some athletes in every major sport have opted out, high-risk players (and middle-aged coaches) who chose to participate are essentially playing Russian Roulette with a partially loaded, invisible gun. If the NCAA and NFL go forward with games this fall, I predict serious medical consequences will ensue, including at least one death.

3. The threat to tradition and normalcy

Visit the chat boards of nearly any Big Ten or PAC-12 team, and you’ll find some posts that would concern any psychologist. Diehard fans in both conferences are emotionally distraught over the cancellation of the fall football season.

That’s understandable. Big Ten football has been around for over 125 years. Its teams played through two World Wars. These will be the first weekends without football for millions of alumni and fans.

But the loss of tradition will have serious repercussions beyond rooting interests. The livelihoods of many employees and businesses, which rely on tourist revenue and fan foot traffic during games, will be compromised, as well. That threat will intensify if other FBS conferences fail to complete their seasons without incident.

4. The threat to “amateurism” in sports

The line between amateur and pro has been blurring for decades. With lawsuits over the likeness of college athletes in video games and the ongoing threat of student-athlete protests over payments, the death of so-called amateurism in sports has been a long time coming.

At the college level, the moneymaking sports of football and basketball continue to stop and restart as presidents and athletic directors hem and haw. For some schools, a canceled season will mean more than $100 million in lost revenue. Already, Stanford University has discontinued 11 varsity programs as a result of projected losses. It won’t be the last institution to scrap non-revenue sports.

A prolonged pandemic will dramatically reduce the size of college athletic departments and, by extension, further diminish the Olympic movement, says sportswriter Sally Jenkins. She predicts, “Some sports won’t survive. Some will return to their club roots.”

Although college athletes are purported to be “students first,” this is rarely the case at the highest levels of competition. In football and men’s basketball, especially, college is a runway for the pros. Canceling an entire season (and perhaps the next) could cause elite athletes to speed up their search for alternatives to the college experience.

5. The threat to youth sports (and kids’ health) 

Since the dawn of organized sports, after-school leagues and travel teams have filled the free time of kids from kindergarten to K12. But with scores of Little League baseball and Pop Warner football teams canceling seasons and tournaments, the initial disappointment (or relief) of parents has given way to a laundry list of questions and concerns.

How do we keep our kids active and exercising? How do we replicate or replace the skills that kids learn through sports and physical education: commitment, focus, teamwork, etc.? And in the absence of a normal fitness regimen, what do we do about the sedentary threat?

Pointing to studies that show kids maintain a stable weight during the school year, but gain weight during the summer, public health experts predict that school closures, combined with the cancellation of organized sports, will exacerbate the nation’s childhood obesity epidemic. What’s more, eliminating social interactions and play time while increasing social isolation and screen time may be a recipe for mental health problems, say pediatric researchers.

Consider, all these problems exist after just five months of partial lockdowns. Imagine the consequences if the pandemic were to drag on for years. Parents, players, owners, and fans are hanging their hopes on a timely solution to the current crisis. Reality, however, will prove highly disappointing to many. The coronavirus isn’t disappearing anytime soon.

In the face of a viral pandemic, it might seem silly to fret so much over the games we play. But losing sports will harm people’s health and well-being, making our current problems far worse in the future.

Robert Pearl is a plastic surgeon and author of Mistreated: Why We Think We’re Getting Good Health Care–And Why We’re Usually Wrong. He can be reached on Twitter @RobertPearlMD. This article originally appeared in Forbes.

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