Julia Louis-Dreyfus on Cancer and Her Fight for Health Care: ‘It’s Terrifying to Get That Call’

When Julia Louis-Dreyfus announced to the world — just after winning her 11th Emmy — that she had been diagnosed with breast cancer, she used the harrowing experience as a platform to demand affordable health insurance for all.

“1 in 8 women get breast cancer. Today, I’m the one,” the actress tweeted on Sept. 28, 2017. “The good news is that I have the most glorious group of supportive and caring friends, and fantastic insurance through my union. The bad news is that not all women are so lucky, so let’s fight all cancers and make universal health care a reality.”

A year and a half later, she’s just as determined to give a voice to other women battling the disease. (An outspoken Democrat, she put together a PSA encouraging people to vote in the midterm election last fall.)

“It is so terrifying to get that call. You can’t believe that it’s happening to you,” Louis-Dreyfus, 58, tells PEOPLE in this week’s issue, on stands Friday. “To have no insurance? Or any means with which to take care of yourself and battle against this hideous disease? That’s unconscionable to me. It’s inhumane. And that’s why I said that.”

Production on the seventh and final season of Veep was delayed while she completed chemotherapy. And when she stepped onto the political satire’s set to begin shooting last summer, it wasn’t just another day of production — it was a celebration of her strength.

RELATED VIDEO: Tony Hale Says Veep Costar Julia Louis-Dreyfus Is Doing ‘Fantastic’ amid Cancer Battle

“During my illness, we had a bunch of table reads and stuff, so we were sort of always together. But first day on set, God, we got into it right away,” she says. “It was pretty packed with a lot of language and stuff like that, and … I would say it was lovely. It was like getting back up on a horse. ‘Oh, yeah. I remember how to ride this thing.’ “

Her costars recall an immense sense of relief that she was back — and funnier than ever as foul-mouthed presidential hopeful Selina Meyer.

“We got our big sister back. She’s healthy. And that was the most important thing, just to see her up in the room, healthy, happy to be there. It was emotional,” says Reid Scott, who plays egotistical charmer Dan Egan.

“Yeah, I think it is that sense of, ‘Oh, she’s okay. Mom’s okay,’ ” says Matt Walsh, a.k.a. bumbling ex-press secretary Mike McLintock. “And also, I think, she’s still got it. She’s back at it, and just dunking on people, and just incredibly good right away. It was really fun to see.”

• For more on Veep, pick up this week’s issue of PEOPLE, on newsstands Friday

The Veep writers kept a list of “enemies” displayed in the room where they worked, most of the names silly inside jokes, like “popcorn.” But during pre-production, they added “breast cancer.”

“When we started and we had our first table read, breast cancer was checked off,” says Anna Chlumsky (long-suffering aide Amy Brookheimer), tearing up. “That was just the coolest.”

As for her health now, Louis-Dreyfus smiles and simply says, “I’m fine. I’m good.”

Veep airs Sundays at 10:30 p.m. ET on HBO.