The New York Yankees and Philadelphia Phillies will not play their series opener on Monday night as scheduled, Major League Baseball announced. The game at Citizens Bank Park has been postponed. The game’s status came into question Monday morning, when the Miami Marlins were confirmed to have a COVID-19 outbreak on their roster.

The Marlins, who played the Phillies in Philadelphia over the weekend in Philadelphia, reportedly have had at least 14 individuals test positive since last week. That group includes catcher Jorge Alfaro, outfielders Garrett Cooper and Harold Ramirez, and pitcher Jose Urena, whose positive test forced him to be scratched from his Sunday start.

In response to that news, the Marlins’ home opener, which was scheduled for Monday night against the Baltimore Orioles, has also been postponed.

Here’s part of a statement from the league:

The members of the Marlins’ traveling party are self-quarantining in place while awaiting the outcomes of those results. Major League Baseball has been coordinating with the Major League Baseball Players Association; the Marlins; the Orioles; the Marlins’ weekend opponent, the Phillies; and Club medical staffs, and will continue to provide updates as appropriate.

Below are three things to know about this story.

Direct response to Marlins’ outbreak

As noted above, the Marlins occupied the visiting clubhouse of Citizens Bank Ballpark all weekend long. Based on what we know about how COVID-19 spreads, the chances of surface transmission appear relatively low. Even so, MLB Network’s Jon Heyman reported Monday morning that the visiting clubhouse is being fumigated “50 different ways” in response to the news.

Phillies quarantine visiting clubhouse staff

Likewise, the Phillies are said to be quarantining their visiting clubhouse staff, who obviously had to spend time around numerous individuals who were infected. It’s unclear how long the Phillies will ask their staff to isolate — ostensibly they will be tested by the team repeatedly over the coming days. (The Yankees, for their part, were preparing to have their own attendants make the trip, per Joel Sherman of the New York Post.)

No positive tests yet for Phillies

It should be noted that, as of Monday morning, the Phillies had not had anyone on their roster or coaching staff test positive for COVID-19 since the season resumed. That could well change in the coming days, of course.The risk of transmission has been shown to be at its greatest when individuals spend a prolonged amount of time in an enclosed or poorly ventilated area and in intimate dimensions. Comparatively, the odds of a player transmitting the virus to a player on another team during a game — often in a wide, outdoor setting and with fleeting close contact — seem low. Low is not the same as zero, though, which explains why the Phillies and Yankees won’t be playing on Monday night.