The positive COVID-19 test in the Seattle Mariners organization belongs to a member of the team's traveling party.
Per ESPN's Jeff Passan, the positive test has caused "concern within the organization about potential spread due to a significant portion of players being unvaccinated."
Ken Rosenthal of The Athletic first reported the positive test in the Mariners organization.
Per MLB's health and safety protocols for this season, individuals who test positive are required to isolate for at least 10 days, must be cleared by the league's Joint Committee and team physician, pass a mandatory cardiac evaluation and a determination that the individual doesn't pose the risk of infecting others before being allowed to return.
Passan noted the Mariners are concerned about a potential outbreak because they are "well short" of the 85 percent vaccination threshold that MLB requires to relax its COVID-19 guidelines for teams.
According to the Associated Press, 14 of MLB's 30 teams have hit the 85 percent mark on COVID-19 vaccinations.
MLB had to postpone the Washington Nationals-New York Mets series at the beginning of the season due to four Nationals players testing positive for the coronavirus. Two games between the Minnesota Twins and Los Angeles Angels on April 17-18 were postponed due to COVID-19 issues involving the Twins.
The Mariners are still scheduled to play the San Diego Padres at Petco Park on Friday night at 10:10 p.m. ET.