First, Aaron Nola cleared Major League Baseball's COVID-19 protocol and finally arrived in training camp with the Phillies.

Then, the star pitcher cleared the air.

Nola never was infected with COVID-19, he said Monday, three days after camp opened and 18 days before opening day against the Miami Marlins. But through contact tracing, he learned that he recently had been exposed to someone who does have the virus and therefore was mandated to stay home for seven days upon arriving in town last week.

"I got testing, but they all came back negative," Nola said via a Zoom call after throwing a bullpen session at Citizens Bank Park. "I never tested positive."

Nola spent baseball’s hiatus in Clearwater, Fla., and later at his home in Baton Rouge, La. He declined to say where he came in contact with a positive case, or whether he was exposed by a teammate or club employee. Last month, the Phillies had a coronavirus outbreak at their Clearwater facility in which 11 people, including six players, tested positive.

According to Nola, players were asked before they came to camp to fill out a questionnaire about the people with whom they had recently been in contact.

Regardless, Nola’s situation highlights another challenge for MLB in staging this season-within-a-pandemic: What if contact tracing reveals that an entire team was exposed to someone who tested positive?

Phillies manager Joe Girardi described the contact tracing this way: “A was with B, B was with C, C was with D, and D was with E, so now we have to maybe make sure that E is OK.”

Girardi reiterated that “when you are in direct contact with someone who has had it, you are going to go through a number of tests.”

"I think for us that would probably be the hardest part," Nola said. "Like me, if you don't have symptoms and you come in contact with somebody who ends up testing positive, you're out for probably at least seven days. That could possibly be two starts. It's obviously going to be a hard part of it. And sometimes it's out of our control. We just have to try to do our part every day."

It's little wonder, then, that Nola held a mask over his face Monday during a conversation near the dugout with fellow pitcher Zach Eflin, who also wore a mask. In a 60-game season, when pitchers likely will max out at about 12 starts, there's no sense taking any chances at all.

Aaron Nola (left) puts a mask to his face as he stops to talk to fellow Phillies pitcher Zach Eflin at Citizens Bank Park.
DAVID MAIALETTI / Staff Photographer
Aaron Nola (left) puts a mask to his face as he stops to talk to fellow Phillies pitcher Zach Eflin at Citizens Bank Park.

Nola’s ERA rose from 2.37 in his breakout 2018 season to 3.87 last year. But he remains one of the most durable and effective starters in baseball. Only Justin Verlander, Jacob deGrom, Gerrit Cole, Patrick Corbin, and Nola worked at least 200 innings and racked up 200 or more strikeouts in each of the last two seasons.

During the shutdown, Nola said, he threw “almost every day” in Florida, including twice a week off a bullpen mound. Once he went home to Louisiana, he returned to the five-day routine that he typically follows during a season, including running, working out, and “up-down” bullpens to simulate games.

But just because Nola has arrived in camp with time to spare before the season begins, Girardi pumped the brakes on announcing with certainty that the 27-year-old right-hander will start the opener. Doing so would make him the first Phillies pitcher to make three consecutive opening-day starts since Roy Halladay (2010-12).

If Nola ends up not being ready, right-hander Zack Wheeler would be next in line to start the opener. But Wheeler's wife, Dominique, is due to give birth to the couple's first child in late July, casting some doubt on his status.

"I've got to give him a chance to see where [Nola's] at," Girardi said. "Because there's adrenaline and there's excitement when you start to get back on the field. I'm not saying he won't be [the opening-day starter] and I don't doubt that he will be ready, but I'm not ready to say that yet."

Last weekend, citing medical privacy laws and MLB policy, Girardi couldn't say why Nola was absent from camp. The Phillies didn't place Nola on the COVID-19 injury list, and even then, players who are put on that list didn't necessarily test positive. In some cases, it's simply because, like Nola, they were exposed to a positive case.

Some teams have asked players for permission to reveal their testing status to avoid public speculation. Nola said the Phillies didn’t discuss that option with him until later, at which point he said he gave permission. But it took Nola’s arrival on Monday to provide clarity on the situation.

“I know that we weren’t able to really reveal anything,” Nola said. “I guess I kind of got caught off guard. I saw on the internet that I tested positive, which was not true. All of my tests were negative. I’m glad I’m here clearing it up right now.”