Currently unvaccinated staff members who receive a first dose of the Moderna vaccine before Oct 4 and have a second dose scheduled would retain their access, the report adds.
The decision comes as the pandemic surges across the US, with a rolling seven-day average of 148,816 positive cases per day as of Sept 17.
The US currently has 55 percent of the population fully vaccinated, with 64.1 percent receiving at least one dose.
The playoffs begin on Oct 5 with the American League Wild Card game, followed by the National League Wild Card game the next day.
The World Series is slated to begin on Oct 26.