Major League Baseball commissioner Rob Manfred believes the health protocols the league has in place are working despite outbreaks of coronavirus on the Miami Marlins and St. Louis Cardinals.

He's calling for "vigilance" from all parties, though the league will institute some new measures in the coming days.

"I think the vast majority of our players have done a really good job adhering to what are difficult protocols," Manfred told ESPN.com on Wednesday morning. "They're contrary to the way people normally live their lives.

"Relatively small deviations from the protocols can cause serious problems. That's a reality. ... Any individual act, you say 'wow, not a big deal,' but those individual acts can cause problems."

The commissioner says the spread of the virus throughout the Marlins and Cardinals -- causing both teams to shut down for a period of time -- can be traced back to lapses in the protocols.