It's an unthinkable scenario that's left a Mackay couple heartbroken.
A week after taking their newborn Eloise home, her mother noticed feeding problems and reported them to a visiting midwife.
But it was a virus that was transmitted by a kiss that saw the baby's health deteriorate rapidly.
Baby Eloise's mother Sarah Pugh has spoken of her anguish to 7News.
"And she said that's far too much [weight] loss for a newborn so she said we had to go straight to hospital," she said.
Tests showed Eloise had been unknowingly infected with the herpes simplex virus in the days after her birth.
Doctors told her parents, she may not make it.
Eloise was airlifted to Brisbane, where she was put on a machine to help her heart and lungs.
Complications arose, and Eloise contracted a staph infection.
At just 24 days old the infant died in her mother's arms.
Doctors believe the herpes virus was passed on by a visitor with a cold sore who gave the young child a kiss.
"We were pretty.. I was pretty shocked that a cold sore had done this," said Sarah Pugh.
Sarah says the community has been extremely supportive and she wants other people to be aware of what could happen.
"I possibly couldn't let another family go through the heartache that we went through," said Sarah.
Doctors say while it's not uncommon for babies to develop a herpes infection, it's rare that a baby will die.
"This is one of those many occasions where prevention really is the only cure," said Obstetrician Dr Gino Pecoraro.
Dr Pecoraro says anyone with a cold sore should cover it with a band aid and refrain from kissing babies and young children.
It's an unimaginable heartache for this family, but for now Sarah says she can't dwell on the terrible outcome.
'Just my other three kids. I can't really... I've just got to stay strong for them," said Sarah.
Sarah has advice for other parents now, so others don't suffer the same fate.
"Be really careful and just make sure people don't kiss them or touch them, and yeah just make sure you wash your hands continuously."