Though she made America laugh for seven years as a cast member on “Saturday Night Live,” Vanessa Bayer has a serious side, including a not-so-secret soft spot for sick kids.

That’s because many years ago, she was one.

“How Do You Care for a Very Sick Bear?” is Bayer’s new picture book for young children and their parents. It tells the simple story of a little bear suffering from a grave illness, and how friends cheer up the cub by bringing snacks and get-well cards and, most important, offer their loving presence.

Essentially, the book is a colorfully illustrated lesson in the Jewish mitzvah of bikur cholim, or visiting the sick.

“Yeah, I did that on purpose,” she says with a laugh.

Bayer grew up in Cleveland’s tight-knit Jewish community, where her mom worked at the local JCC. She attended so many bar and bat mitzvahs as a teen, it wasn’t hard for her to later develop her signature “SNL” character, Jacob the Bar Mitzvah Boy.

But when she was diagnosed with leukemia at age 15 and frequently had to stay home from school over the 2½-year course of treatment, she discovered the importance of human interaction.

“Obviously it was a really difficult time,” she recalls, “but friends and family really did rally around me and always made me feel included. Friends would come visit and give me the ninth-grade gossip. I wanted to write this book because I noticed as I’ve gotten older that when someone is sick, people don’t know what to do to help them.”

Even though the book is written for children, Bayer didn’t shy away from the more unsettling aspects of consoling sick friends: seeing them out of sorts, in pain, sad and sometimes wanting to be alone.

“It’s scary to have a friend who’s sick,” Bayer says, “but what I’m trying to teach people is that the best thing to do is reach out and be there for them.”

That wasn’t the only lesson Bayer learned during her illness. She also discovered that humor helped her heal. In fact, she traces her desire to make people laugh to the jokes and laughter that buoyed her during her illness.

In college she tried her hand at improv comedy, later moving to Chicago. In 2008 she co-starred in Second City’s “Jewsical! The Musical,” which featured an all-Jewish cast. Among other characters, she played an edgy Virgin Mary with a New York accent.

In 2010 she joined the cast of “SNL,” where she enjoyed a stellar run. Characters included her spot-on Miley Cyrus and Jennifer Aniston (she had the chutzpah to do the impressions in front of both stars on live television), and her overeager, overachieving, bad child actor Laura Parsons.

But her most memorable character was Jacob the Bar Mitzvah Boy, who usually appeared around the time of a Jewish holiday. In his ill-fitting suit and New York Yankees kippah, Jacob would painstakingly read prepared remarks, not unlike a stilted bar mitzvah speech, expounding on the holiday, making bad jokes about his big brother Ethan and looking terribly awkward.

Jacob has a place right up there in “SNL’s” Jewish hall of fame, alongside Jon Lovitz’s Hanukkah Harry, Adam Sandler’s “Hanukkah Song” and Gilda Radner’s “Jewess Jeans” commercial.

“He was probably my favorite character,” Bayer says. “He’s very similar to my personality. He was based on my brother [Jonah], so it was very natural to do the character, but also nice to do it at ‘SNL’ and to do it for the Jewish community.”

How did she capture the supreme awkwardness of a 13-year-old boy so well?

“There is something so funny about boys at that age,” she says. “A bar mitzvah is so young for a boy to have to be so formal. Girls are already more evolved. But boys don’t know what to do with their hands, they can’t handle any distractions.”

Bayer left the show in 2017, but she has also appeared in the movie “Trainwreck” and TV shows including “Will & Grace,” “Single Parents” and the Netflix sketch comedy “I Think You Should Leave.”

Right now, though, she’s all about her book and spreading its message of healing. Her recent book tour took her to the Cleveland hospital where she was treated years ago. This time, she read to children experiencing the same things she did.

“It was just a reminder that everybody is going through something,” she said of the visit, “so let’s all just be there for each other.”