A few weeks ago, Angelique Lucero's 2-year-old daughter Sophie was diagnosed with the respiratory illness RSV, short for Respiratory Syncytial Virus.
Similar to the flu, but with no vaccine and slightly different symptoms, it can be spread quickly at daycare centers.
Sophie recovered quickly, but when her little brother Zaiden, just 6 weeks old, began coughing and then throwing up on New Year's Eve, Lucero knew it was serious.
"It's terrifying," she said.
She brought her newborn to the hospital, and doctors transferred him to the ICU at Children's Hospital Colorado.
“The doctor came and got me and said, 'We’re putting a breathing tube,'" said Lucero. "And I’m trying not to cry."
Zaiden is tiny. The machines working to save his life are big.
“For a lot of our really, really young infants, kids under five-years-old, or our older adults, or anyone whose immune system is somewhat weak, this can actually be really, really deadly so it’s something you have to be on the lookout for especially as a parent," said 9NEWS medical expert Dr. Comilla Sasson.
Most kids get RSV before age 2. Symptoms include coughing, not eating and breathing issues, according to Sasson.
“I never heard of RSV, I just heard of the flu, but I didn’t think it was this serious in kids," said Lucero. "I did not."
Her son Zaiden was scheduled to have lung bypass surgery but started to get better on his own and is stable now. Lucero doesn't want other moms to go through this.
“I took it for granted," she said. "I feel like I’ve taken their health for granted, and then something like this happens and it’s very eye-opening what germs can do.”