Myocarditis is an inflammation of the heart muscle and can lead to more serious conditions like heart failure, arrhythmias or cardiomyopathy. Doctors believe that Rodriguez's previous bout with the coronavirus—he tested positive before the team resumed its training camp this summer—led to myocarditis.
"That's why the doctors tell me to just take a week, just rest, don't let your heart get too much heart rate," Rodriguez said. "If it goes away, just go back to work."
Doctors also told Rodriguez that 10 to 20 percent of patients diagnosed with COVID-19 are also diagnosed with myocarditis.
"That's the most important part of your body, so when you hear that, the first time I hear it was kind of scared a little," he said. "Now that I know what it is it's still scary, but I know exactly what it is. Just talk to my mom, talk to my wife, they know what I have and everything. Now we just gotta take the rest. That's hard, but you gotta take a rest."
Rodriguez said he is no longer feeling any coronavirus symptoms after it had left him feeling "100 years old."
The 27-year-old was expected to be Boston's top starter this season after David Price was traded to the Los Angeles Dodgers and Chris Sale was lost for the season after having Tommy John surgery. He went 19-6 in 2019 with a 3.81 ERA, 1.33 WHIP and 213 strikeouts in 203.1 innings.
In Boston's patchwork rotation he was expected to be one of the reliable options remaining, along with Nathan Eovaldi, who started on Opening Day.
As for when he might be able to return to the mound, that remains to be seen, though he does intend to play this season.
"As soon as I throw the first ball, I'll let you know. I need to know how my shoulder feels," he said. "It could be more, it could be less. It depends how it feels the first time I throw the ball."