After being stuck indoors for months due to Covid-19, many professional and amateur athletes are now returning to center field. But some are wondering if sports may be restarting too soon.

The National Basketball Association just announced that 16 of its players have tested positive for Covid-19. To date, 40 Major League Baseball players are known to be infected. Major League Soccer, which has had 24 players already test positive, is thinking of resuming its season next week. And it’s not just the players—staff are falling ill as well.

The problem with sports like football, baseball, soccer, and hockey is that their athletes are constantly too close for comfort. Every practice and every game, they’re face-to-face, sharing equipment, and almost always breathing heavily on each other. Social distancing is near impossible on the field, and equally challenging in locker rooms. In fact, the locker room is the definition of a Covid-19 hotspot: a damp, steamy indoor space in which contact with others is unavoidable.

To protect players and staff, many teams and leagues are looking to corral them into a so-called “bubble”—a restricted environment intended to limit potential spread of the virus. The soccer players of the San Jose Earthquakes, for example, are staying at a Disney resort where they must keep to their rooms whenever they’re not out on the field or gathering for meals.

This approach is patchy and problematic for many reasons. Restricting the mobility of a group of people isn’t enough to eliminate all risks—neither for the group, nor for the outsiders who brush up against them. One answer to this is to mandate testing for all players, but even that measure has its shortcomings, not least among them the threat of false negatives. There is also a chance that someone who recovers and tests negative might be able to spread the virus still.

Another problem with the “bubble” idea to consider is that sports teams will be exposed to other teams when they play games. This introduces another variable: the new people the team will be in contact with. Not only must the safety of the visiting players be ensured, but that of visiting staff members and coaches. By allowing teams to play each other, the teams and leagues are completely going against the idea of what a bubble is supposed to be.

The final, but not insignificant, issue that must be reckoned with is how to actually enforce the bubble in the first place. Asking a group of young athletes to remain indoors and out of contact with girlfriends, boyfriends, family, and friends is one thing. Ensuring they adhere to these demands is another entirely.

Even in the midst of a global pandemic, sports haven’t lost their importance. Not only do they provide fans with a sense of normalcy, they also serve as a much-needed form of enjoyment and an escape from reality.  But the fact remains that restarting sports too soon will open the door to numerous high risk transmission events—whether for players and staff, or for fans crowding the stands.

Cody Lyster was a 21-year-old college baseball player who caught Covid-19 in April. Because Cody was a young athlete who had no existing health conditions, his family was sure he would make a successful recovery. However, within days of developing symptoms, he was put on a ventilator; on April 8, he passed away. Even young athletes are not immune to infection with Covid-19, and if they’re required to play on sports teams during the pandemic, it is likely that many more will contract the virus.

While sports teams can attempt to reduce the spread of Covid-19 among players and personnel by taking precautions—such as regular testing, reducing physical contact, maintaining six feet of distance between players, enforcing mask wearing, and constantly disinfecting equipment and locker rooms—sports are inherently high risk events. Our main priority should be keeping athletes, staff, and fans safe. To do so, we must slow down our approach and rethink when to restart sports altogether.