In total, nine Cardinals players have tested positive for the coronavirus since last week, with the latest two positives coming from samples collected over the past two days.
MLB earlier said Friday's game had been postponed, allowing for additional testing and contact tracing. The league announced later that Saturday's and Sunday's games had also been postponed.
The Cardinals have not played since July 29 because of positive coronavirus tests. The team previously announced that it had returned 13 positive tests from its traveling party, with seven of them coming from players.
The Cardinals had returned to the field for light workouts Wednesday after being cleared to travel back to St. Louis from Milwaukee late Tuesday.
"Based on the information MLB has shared with us, postponing this series is a necessary step to protect the health and safety of the Cardinals and the Cubs," Cubs president of baseball operations Theo Epstein said. "Therefore, it is absolutely the right thing to do. While it's obviously less than ideal, this is 2020 and we will embrace whatever steps are necessary to promote player and staff well-being and increase our chances of completing this season in safe fashion.
"We will be ready to go on Tuesday in Cleveland. In the meantime, we wish the Cardinals personnel involved a quick and complete recovery."
MLB released its most recent testing numbers Friday. The league said there were 13,043 samples taken last week with 13 positive results for a 0.1% positive rate. During the monitoring phase, there have been 53,826 overall samples that have returned 71 positives for a 0.13% positive rate. Of those 71 positive results, 49 are players and 22 are staff.
Among the Cardinals players who confirmed they tested positive for COVID-19 were two All-Stars, catcher Yadier Molina and shortstop Paul DeJong. All-Star right-hander Carlos Martinez also went on the injured list, though no reason was given. Infielders Rangel Ravelo and Edmundo Sosa and relievers Junior Fernandez and Kodi Whitley also have been identified as testing positive.
St. Louis manager Mike Shildt said earlier this week that there was still some uncertainty about how the virus swept through the clubhouse, but the Cardinals believe it was introduced from someone asymptomatic who came into contact with the team.
Cardinals president of baseball operations John Mozeliak said there has been frustration, but the team doesn't want to put people in a position to get sick.
"I don't know what our future looks like at this point. All I know is we've lost these three games and we'll take this day by day. For all the optimism we had a couple days ago, where we are today, is definitely frustrating for everyone involved," he said. "Hopefully we get through this and get back to playing baseball soon."
Before Friday's postponement, the Cardinals had already added three doubleheaders against the Milwaukee Brewers to a previously scheduled series to make up their three games postponed last weekend. Milwaukee will host doubleheaders Sept. 18 and 20 and will serve as the home team in the opener of a twin bill in St. Louis on Sept. 25.
The Cardinals will make up this week's series against the Detroit Tigers with doubleheaders Aug. 13 and Sept. 10. St. Louis had been scheduled to play the Chicago White Sox at the Field of Dreams in Iowa on Aug. 13. Those teams will play in Chicago on Aug. 14 instead.
Information from The Associated Press was used in this report.