Theater always depends on understudies, but never more so than in the omicron winter.

In late December on Broadway, “The Music Man” lead actor Hugh Jackman gave a moving curtain-call tribute to the industry’s unsung heroes after understudy Kathy Voytko filled in for Sutton Foster.

“I’m emotional because it humbles me — the courage, the brilliance, the dedication, the talent,” Jackman said in the widely circulated speech. “The swings, the understudies — they are the bedrock of Broadway.”

At around the same time, though, Broadway League President Charlotte St. Martinmade comments(for which she later apologized) in a Hollywood Reporter interview theorizing that one reason some shows were closing was that some understudies “aren’t as efficient in delivering the role as the lead is” or weren’t as experienced.

These two incidents span extremes of the understudy experience. Understudies are hailed as saviors; they’re overlooked or disparaged as makeshifts.

For understudies in the Bay Area right now, as the variant makes them more in demand than ever, the reality is even more complicated.

‘Astonishment, horror and glee’: Bay Area understudies recount on- and offstage drama

在大公司和百老汇音乐剧,there’s an elaborate taxonomy for understudying. An umbrella term is “covering.” An “understudy” will usually already be performing an unnamed part in the ensemble but be prepared to cover for a named character. A “standby” waits offstage but is also prepared to cover a lead character. A “swing” can cover any track in the ensemble. At smaller companies, “understudy” might cover all these roles.

“Your job as the understudy is to keep the show open so that the work that all these other performers did can still happen,” said San Francisco actor Nic A. Sommerfeld, who’s understudied locally five times, including stepping up four times in Marin Theatre Company’s“Georgiana and Kitty: Christmas at Pemberley”this winter.

“There can be the stress of whether you match up, whether you’re quote-unquote ‘as good,’ ” Sommerfeld added, “and I don’t think that attitude is as helpful as just remembering that what you’re doing is making the show have another performance.”

That doesn’t mean that understudying isn’t artistic, noted Vishal Vaidya, who’s currently understudying for John Gallagher Jr. inBerkeley Repertory Theatre’s“Swept Away”while also serving as an ensemble member.

“Someone like John Gallagher is a magical actor,” he said. “I can’t re-create that magic; I have to find my own magic.”

“Understudying is a blend,” he went on. “You don’t want the audience or the other actors to really feel like so much is different, because you have to honor the show that was built, but in order to honor the truth of the acting, you have to give it your flavor.”

Sommerfeld, who uses plural pronouns, found themself delving deeper into craft as they kept covering for principal actor Zahan F. Mehta, who had a back injury.

“The first show was just about making it happen. It was honestly a blur to me,” they said.

Their character happened to be a nervous person, so they were able to draw on their own in-the-moment feelings. “But by the fourth time I did the show, I found myself almost wishing I was getting notes,” they recalled. “I was starting to lean into certain moments and, other than audience reaction, didn’t really know what worked.”

San Francisco freelance casting director and Casting Collective founding member Laura Espino, who this season is casting San Francisco Playhouse’s shows, said that understudying demands a special kind of artist.

“You have to be satisfied with just playing the part in front of your closet mirror in your bedroom — and do it just as well,” she said.

Understudies have to deal with at least as much stress for a fraction of the glory and usually less pay. Self-motivation is key.

“You are the rehearsal process,” Espino said. “You are your director.”

Still, there can be great joy in it. San Francisco actor Michael Phillis recalled going on as understudy in his favorite role in his favorite play — Prior Walter in“Angels in America”— at Berkeley Rep in 2018.

“Your whole career flashes before your eyes,” he said. “You’re about to prove what all that money and study and struggle to be an actor was for.”

但也可以导致雅图的深切关注r who’s hurt or sick. Actor Kenny Toll, who’s now based in New York, remembered filling in for Joe Estlack, who had a back injury, during two technical rehearsals for“Bonnie & Clyde”at Shotgun Players, with the possibility that he might have to perform as well.He was ready to help — it was his job — but Toll and everyone else’s concern for Estlack, who soon recovered, cast a pall.

“Understudying is not as glorious or wonderful as it’s often portrayed,” Toll said. “It was a really awful thing. (The show) was Joe’s piece. That piece of theater was built for his body.”

Understudying demands extraordinary memory. San Francisco actor Rodney Earl Jackson Jr. has worked in various understudy capacities in several Broadway shows and tours — “Ain’t Too Proud: The Life and Times of the Temptations,” “Motown: The Musical,” “The Book of Mormon” and, most recently, “A Christmas Carol” at BroadwaySF’s Golden Gate Theatre. In “Ain’t Too Proud,” he had to know all five harmonies of the five Temptations; he also had to memorize separate choreographies — who entered on beats one, three, five and so on.

“I’ve got to have the mental capacity and gymnastics to switch between them,” he said.

Jacob Keith Watson, another “Swept Away” ensemble member and understudy, says that his many years of understudying and swinging have given him an odd skill.

“I call it ‘swing brain,’ where you accidentally know other people’s stuff,” he said. It comes from having to learn where and how to enter and exit, to grab and deposit every prop, all by watching from afar instead of doing it himself.

“Randomly, someone will be like, ‘I don’t remember where I come in,’ and out of nowhere, I’ll be like, ‘Oh, you come in stage left. Couldn’t tell you why I know that. I just saw it once, and it stuck in my brain.’ ”

That skill comes somewhat in handy right now in rehearsal, when his ensemble role in “Swept Away” requires him to be asleep and keep his eyes closed for a long stretch — time when in an ideal world he’d be simultaneously observing Wayne Duvall, the actor he’s understudying. “I can kind of hear that he’s stage right,” Watson said.

Right now, Espino said, the bulk of her work at the Casting Collective — a small, new local outfit — is finding understudies, as a result of concerns about the omicron variant. The increased likelihood that an understudy will go on, she added, is tantamount to having to cast a role twice.

At Berkeley Rep, Vaidya, Watson and other understudies don’t go anywhere besides their hotel or the theater. They know that if they took risks, they’d risk everyone else’s health too. They’re also aware that these gigs, with a greater chance that at some point they’ll have to perform, could mean exposing themselves to contagion. Yet union actors don’t qualify for health insurance unless they work a certain number of weeks per year, which complicates the calculus for any job opportunity.

Still, Vaidya spoke with calm pragmatism about the possibility of filling in: “I’m ready, but I’m still going to feel like I’m shot out of a cannon.”

“Swept Away”:Book by John Logan. Music and lyrics by the Avett Brothers. Directed by Michael Mayer. Through March 6. $37-$186, subject to change. Berkeley Repertory Theatre, 2025 Addison St., Berkeley. 510-647-2949.www.berkeleyrep.org