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Although the regular season is less than a week old, Major League Baseball is already dealing with a coronavirus outbreak. The Miami Marlins have now had at least 17 test positive since Opening Day among players and coaches. Four players tested positive over the weekend, an additional seven on Monday, and then four more on Tuesday.

MLB is intent on moving forward, and plugging along through a 60-game season, though the Marlins and the Philadelphia Phillies, who hosted Miami over the weekend, have been put on a temporary pause until things get better. We now know that the Marlins are off until Monday, Aug. 3 at the earliest while the Yankees and Orioles are changing plans to play each other this week before resuming their previous schedules this weekend. Philadelphia, meanwhile, can resume its schedule as early as Friday. 

Whether or not MLB can get to the postseason -- and the fat TV checks that come with it -- at this point in the year is anyone's guess, and hinges in part on what the league does with the Marlins over the coming days. 

How did the Marlins get here?

The Marlins first had a positive test result on Opening Day, when Jorge Alfaro was placed on the injured list shortly before the team's season opener in Philadelphia. Here's a timeline of what happened between then and Monday.

Friday, July 24 (Opening Day vs. Philadelphia)

  • Alfaro tests positive and misses opener. No other Marlins have positive results.

Sunday, July 26

  • Three other players, including scheduled starter Jose Urena reportedly test positive. Urena is scratched from his Sunday start. The rest of the team learns about the positive tests, but decides to play Sunday's game as scheduled.
  • The Marlins do not travel home as scheduled after winning the series finale at Citizens Bank Park. Instead, the team stays in Philly and awaits another round of test results.

Monday, July 27

  • Another round of testing shows a full-blown outbreak for the Marlins. Eleven players test positive for COVID-19, and reportedly at least 14 total team members are positive.
  • MLB postpones the Marlins' Monday night home opener vs. the Orioles in Miami, and the team stays quarantined in Philadelphia.

Tuesday, July 28

  • Four more players tested positive.
  • The Marlins remain quarantined in Philadelphia.
  • One player who previously tested positive now tested negative, per Ken Rosenthal.
  • The league issued a press release announcing the Marlins aren't going to play until Monday, Aug. 3. 

Dr. Zachary Binney, an epidemiologist at Oxford College of Emory University, told's Scott Davis that the league should conduct an investigation to discover how the Marlins outbreak occurred so that it can reinforce its policies. "Was there some risky behavior from players who, say, went out to a bar or nightclub?" Binney asked. "Is that where this started, or was the spread mostly occurring at the Marlins facility, in the dugout or in the clubhouse? And if so, where did MLB's protocols either break down or where were they too weak to begin with, and how can we improve the situation?"

How long will the Marlins (or Phillies) quarantine?

Dr. Binney also said he would advise MLB to quarantine the Marlins for two weeks, and to do the same for the Phillies for five days, with test results dictating if that period was extended or not.

The reasoning is straightforward: COVID-19's incubation period can vary from between two to 14 days, according to the Center for Disease Control. Harvard Medical School estimates that there's a 40 percent chance of a negative test if you're tested four days after being exposed to the virus. It's possible that a player could test negative before later testing positive, by which point they would have potentially infected others. 

In the Marlins' case, another outbreak in a few days could completely compromise the other half of the team. This is why they aren't playing again for another week. 

That's just focusing on the Marlins themselves. It ignores that the Marlins could have infected the hotel staff, bus drivers, clubhouse attendants, and others in recent days, contributing to the community spread in Philadelphia before potentially doing the same in Baltimore and elsewhere. (Maybe it's no wonder why Pittsburgh wasn't on board with welcoming the Blue Jays.)

With the league announcing Tuesday that there were zero new cases on any non-Marlins teams, they laid the groundwork to let the Phillies start playing games again this weekend. Their three-game series with the Blue Jays is on. 

Did the Marlins expose anyone else?

It's possible that the Marlins could have infected Phillies players, continuing a chain that might have preceded that series. Cross-team transmission seems unlikely if the players' only interaction with each other is on the field -- the highest-risk activities have been found to involve prolonged exposure to large crowds in enclosed or poorly ventilated areas at intimate distances; none of which, for the most part, would seem to come into play during a baseball game.

Still, it makes for an unnerving coincidence, at minimum, that the Marlins played an exhibition game (that included a rain delay) against the Atlanta Braves before traveling to Philadelphia, and that the Braves have been without their top two catchers since due to COVID-like symptoms. Both Travis d'Arnaud and Tyler Flowers have tested negative so far, and there's yet to be evidence that the Marlins infected any Phillies.

Even without that team-to-team transmission, it's easy to see how MLB could have a bigger outbreak on its hands, within the Marlins or some other organization, if it doesn't proceed with caution. Perhaps that's why Dr. Arthur Morris, a professor of infectious diseases at the University of Toronto, told Rob Gillies of the Associated Press that, "anyone who knows anything about this problem and infectious disease epidemiology could have anticipated this. This plan was designed to fail and they went through with it anyways."

As noted, the MLB press release Tuesday laid out that there have been zero new positive tests on any non-Marlins teams, but that doesn't mean all tests in the coming days will remain negative. It's a touch-and-go situation for sure.