Annie’s brows drew together at the unfamiliar word in her third-grade history lesson. She swiveled from her screen to face her mother.

“What are doctors?”

“They were people specially trained to care for sick people.”

Annie was still perplexed. “What’s sick?”

Her mom patted the place next to her on the sofa. “Come here, and I’ll explain it to you.”

With her daughter settled in, she began.

“Do you remember when all your goldfish died?”

“Yeah. Goldilocks went first, then the rest of them a few days later.

They all must have had short telomeres.”

“Wow, girl!” Her mother turned to face Annie. “That’s a big word. Do you know what it means?”

Annie shook her head. “No,” she said quietly. “But everyone says that when someone dies.”

“Let’s start with DNA. You learned that last year.”

Annie closed her eyes and recited the lesson.

“DNA is a double-stranded helix.” Her hands pantomimed the shape.

“It contains the genes needed for development, functioning, growth, and reproduction.”

“Good job! So, DNA has two strands, like two shoelaces. Telomeres are the ends of the laces — the plastic tips.”

“What does that have to do with dying?”

“Telomeres protect DNA, but the telomeres shorten as we get older. Eventually, they get too short to do their job, so we age and die.”

“But my goldfish weren’t old!” Annie’s voice rose. “So why did they die?”

“Because they got sick. They got a disease. My guess is that Goldilocks caught a germ and gave it to the others.” Her mother stood and headed to the kitchen. “Cookies and milk time?”

Annie grinned. “Chocolate chip, please!”

The replicator tray opened with hot cookies, filling the kitchen with the aroma of chocolate, and Annie dove for them.

“How come we never get sick?” Annie mumbled through her mouthful of cookie crumbs.

“Thank the doctors for that.”

“But there aren’t any here to thank, Mommy.”

Her mom nodded. “Centuries ago, because they didn’t want people to get sick, doctors created vaccines to prevent all diseases. Since then, every baby has gotten the vaccine to protect it for life. That’s why you’ve never been sick. Isn’t that wonderful?”

“Yeah. But didn’t it make them sad that they had nothing left to do?” Annie brushed a tear away.

“No. Listen. About a hundred years after the vaccine’s invention, a little girl like you asked the same question to a discussion group online.

“Here’s the answer one man gave. I remember it because it became famous.”

Annie leaned over to read the words on her mom’s hologram screen.

“From the beginning of time, doctors worked hard helping others to heal, but they couldn’t prevent any illnesses. First, they made vaccines to prevent a few diseases. Eventually, they invented vaccines for all of them, so doctors weren’t needed anymore. The medical profession has been the only one whose ultimate goal was to make them no longer necessary.”

Judy Salz is an internal medicine physician and author of Worthy.

Image credit: Shutterstock.com