NEW YORK -- For the third time in the past four days, the Yankees lost a key member of their club to COVID-19, as catcher Gary Sánchez tested positive on Thursday, manager Aaron Boone revealed via Zoom.

After starting pitchers Gerrit Cole and Jordan Montgomery missed their scheduled starts this week, the Yankees backstop was not in the lineup for Thursday’s series opener against the Mariners. Boone said Sánchez did not feel well Wednesday night as he left Yankee Stadium, and when his condition did not improve the following morning, he took a rapid antigen test that indicated he had contracted the virus. He took a molecular PCR test later Thursday to confirm the results and was placed on the COVID-19 injured list.

No other Yankees players were held out of the game against Seattle for contact-tracing purposes and catcher Rob Brantly was added to the roster as a replacement player.

“I guess I’m a little concerned about everything,” Boone said. “We continue to get hit by some things; we just got to deal with it the best we can and try and get the best care for our guys. ... [We’re] just trying to be responsible, safe. You know, I think all of us, the country, everyone’s learning as this thing continues to evolve.”

The Yankees had just reinstated lefty reliever Wandy Peralta from the COVID-19 injured list before Thursday’s game when the news about Sánchez broke. This season has presented that type of recurring challenge often for the Yanks, who have seemingly been disproportionately affected by outbreaks among Major League Baseball clubs.

Just three weeks ago, six Yankees players -- Aaron Judge, Gio Urshela, Kyle Higashioka, Jonathan Loaisiga, Nestor Cortes Jr. and Peralta -- tested positive for COVID-19, forcing the postponement of their home game against the Red Sox that was supposed to open the second half of the MLB season. Peralta was the last of that group to return to action for the Yanks.

“Yeah, it does seem like that. It definitely seems like we’ve been hit a little harder,” Boone said. “Once we actually started camp last year, I think we made it through the whole year without anything. [But] obviously we’ve been hit pretty hard, and of late, too [this year].

“It’s a different kind of adversity, obviously, that we deal with in 2020, 2021, but it’s something that we’ve got to deal with nonetheless. The guys have done an excellent job, [when] it’s created opportunities for other people to step in and step up. And that’ll continue to be the expectation.”

One of those players who stepped up in a big way was outfielder Greg Allen, whose contract was selected from Triple-A Scranton/Wilkes-Barre on July 16 and who joined the Yankees’ active roster alongside some of his RailRiders teammates to help New York plug in its holes coming out of the All-Star break.

Allen was optioned back to the Triple-A squad after Wednesday’s 10-3 win over the Orioles, having hit .270 with an .849 OPS in 15 games, a stretch during which the Yankees went 11-4. Boone admitted Thursday that sending Allen down was a “very difficult” decision, but it ultimately came down to the Yankees’ ability to add necessary depth for the stretch run of the season in outfielder Jonathan Davis, who was claimed off waivers from the Blue Jays on Tuesday and added to the active roster on Wednesday.

Since Allen was called up as a replacement player during that July outbreak, the Yankees didn’t have to expose him to waivers when sending him back down. Boone framed the move as one in which “we don’t lose Greg Allen.”

“First and foremost, what a good pro he’s been in the room. But also, he’s performed and helped us win games,” Boone said. “This is a situation of the opportunity to get a guy like Jonathan Davis. ... The opportunity to create depth in any season, but especially with what we’re going through in 2021 -- you probably can’t have enough depth going forward.”

That is a lesson that has come hard learned for the Yankees this season. With Sánchez joining Cole and Montgomery on the COVID-19 IL, it won’t be any easier any time soon. But these Yanks have proven to be battle-tested, and Boone is confident that this will be just another dent in their pinstriped armor.

“Everyone’s gotten better at that. Less shock each time, even though we’ve had really significant people on our team have it happen to them,” Boone said. “So I think the more and more it happens, the more you’re not completely caught off guard or floored by the news. You just check in on the individuals and see how they’re doing and make sure they’re OK.

“But from there it becomes, ‘All right, what do we have to do baseball-wise to move on and go out and try and grab a W?’”