CARLSBAD, Calif. — A 6-year-old’s parents had no idea she’d be battling cancer when they enrolled her in a coronavirus vaccine trial.

Layla Mahoney is one of 60 children in the San Diego area who are taking part in Moderna’s clinical trials. She’s also one in only 200 people across the country diagnosed with a rare brain cancer each year.

Every dad wants to give his daughter the world and Shawn Mahoney nearly has. As an underwater cinematographer, he’s taken Layla globetrotting since she could walk.

“She’s been to Fiji, she’s been to Costa Rica. She’s been to Mexico a bunch of times. She’s been all over the U.S., I mean she had her first passport when she was 2,” Shawn Mahoney said.

Unfortunately, their latest adventure landed them at Rady Children’s Hospital this summer. Painful headaches and vomiting led the Mahoneys to take Layla to the emergency room and 36 hours later, she was in brain surgery.

“She was screaming, like ‘Daddy, save me. Help me. Do something,’” Shawn Mahoney said. “They did a CT scan and it revealed a massive brain tumor, about the size of a golf ball, in her head.”

The Mahoneys were in the midst of trying to protect Layla from COVID. They’d already signed her up for Moderna’s study of its vaccine in young children.

“This shouldn’t have happened in terms of getting her into the trial. It just shouldn’t have, there’s so many reasons why she shouldn’t have been in there, but she is and that’s pretty amazing,” her dad said.

Had Moderna called 10 minutes later — after Layla was diagnosed with cancer — she would have been disqualified from participating. To Shawn, that timing is everything.

“We can beat cancer, but if she has to go through radiation and then eventually chemo, where she’ll basically have no immune system, she could get COVID and die.”

Layla was less enthused about getting the shots during the trial, but signs seem to indicate she got the vaccine and not a placebo. She showed some common side effects after her second dose.

“Last time I tensed my arm up and they had to like wrangle me,” Layla said. “I felt fine then my dad walked out and said, ‘Are you OK?’ and I said I’m really tired and also cranky.”

To turn Layla’s frown upside down and help with mounting medical bills, the family started a fundraising campaign with an emphasis on fun. They’ve raised $70,000 of their $100,000 goal and plan to donate portions to St. Jude Children’s Research Hospital and causes that support animals. Layla, a budding veterinarian, gets to choose the organizations.

“Just in the past week, she’s had an elephant in Zimbabwe adopted in her name. She’s had a great white shark named after her,” Shawn Mahoney said.

There will be tough days ahead as Layla starts chemo in December. The family doesn’t know what the future holds for her cancer but they know they’ve armed her to fight COVID. It’s something the Mahoneys recommend to all parents, especially those who are hesitant. 

“An internet connection and a keyboard does not equal research. It just doesn’t,” Layla’s dad said. “Talk to the medical professionals. Look at the data that’s available. Look at the numbers, look at the odds.”

Odds are something the family intends to beat every day.

“She’s my buddy, you know? We just have this bond. And seeing her go through this has been brutal.”

Layla will soon know if she got the vaccine or placebo during the trial. If the CDC approves a vaccine for young children before Moderna’s is approved, she can withdraw from the trial and get vaccinated, her parents said.