The first few days after bringing home their newborn daughter were a joy for John and Louise Wills.

Their delightful newborn Eibhlin, born on November 19th 2015,  was feeding well and sleeping and the new parents were besotted with their tiny baby.

“She was perfect, so placid and relaxed,” Louise recalls with joy in her voice.

When she became slightly congested and out of sorts they didn’t think twice as John himself had recently had a cold, but there was no cause for alarm they thought as she was sleeping well.

John and Louise Wills. Image Via Facebook.

But their newborn's colour changed and she became listless they grew concerned and took her to hospital near their home in Ireland's capital, Dublin.

John and Louise never suspected a thing but tragically she deteriorated quickly. To their horror, just hours after they arrived at emergency, Eibhlin was pronounced dead.

It was 1:09am -  one week after she was brought home.

John Wills told Mamamia in a statement: "She was handed to Louise and I wrapped in her blanket with her little eyes closed."

The devastated family and medical staff never suspected what a post mortem revealed days later.

Eibhlin died of the cold sore virus.

“They did their best but they couldn’t save her. Cot death was ruled out. There were no red flags until it was far too late,” Mr Wills told RTE.

Eibhlin died of the cold sore virus. Image supplied.

The heartbroken couple have turned their grief into good, by using Eibhlin's death as a way to speak out about how this common virus can kill.

“In 90 per cent of cases the virus is transferred from mother to baby, but Louise was cleared. It came from another adult. The heel prick test taken when she was still in the hospital indicated that she had contracted it in the hospital. In the place where she should have been safest," Mr Wills said.

“We don’t know exactly when she got it, we just know it was shortly after birth. It came from someone within the hospital.”

Eibhlin's mother Louise told RTE: "In a place where she should have been safest, she contracted it there.”

“It could be a simple accident or someone accidentally touching their cold sore and then giving her a drip or food or doing something.”

Watch: Eibhlin's father explains why he went public with their story. Post continues after video.

Eibhlin's parents were in "total shock" when they realised that such a common virus as a cold sore caused their daughter’s death, and horrified at the lack of information available.

“In Eibhlín's legacy we now want to ensure the general public is aware how lethal a cold sore can be to a new born baby,” she said.

HSV (Herpes Simplex Virus) is spread by direct contact with an infected site, saliva or genital secretions. The most common means of transmission including kissing, genital contact or direct contact with an infected site such as hands.

John and Louise suspect that a nurse may have accidentally transferred it to their newborn while in hospital.

They told Mamamia in a statement: "In Eibhlin’s case it was Disseminated Neonatal Herpes Simplex Virus 1, which incubates for a time and results in multiple organ failure but it remained asymptomatic until it was too late. By the time the symptoms were evident it had (according to the post-mortem) devastated her bowel and liver."

John and Louise have now launched a website and are actively  campaigning to ensure other families know about the dangers of cold sores.

"We are sharing our story in Eibhlín’s memory so we can create awareness about the dangers of cold sores and new born babies."

John wants parents to know the risks. Image via YouTube.

They want cold sore sufferers to be mindful of the virus, and new parents to be careful about who kisses their newborns.

"We want all parents, parents-to-be and any medical staff working with them to be made aware of the risks so no one else ever has to face what we have gone through,” said John.

"We are determined to do something for her," Louise said.

To access their website go here: Remembering Eibhlín