The Philadelphia Phillies have brought all team activities to a screeching halt ... after 2 members of the organization tested positive for the coronavirus.

Remember, the Miami Marlins announced a serious COVID-19 outbreak after playing a series in Philly over the weekend ... with at least 19 reported cases as of Thursday morning.

The problem -- some Marlins players reportedly found out they tested positive for COVID prior to Sunday's game against the Phillies ... but the rest of the team decided to play anyway.

Now, the Phillies are reporting 2 members of the team -- zero players -- have tested positive ... and are taking no chances at letting things get worse.

The team says it's shut down all team activities "until further notice" ... which also leaves the Phillies' weekend series against the Toronto Blue Jays up in the air.

The Phillies' series against the Yankees was postponed due to the COVID outbreak ... but MLB commish Rob Manfred says the outbreak is "no nightmare."