Vanessa Lachey felt "traumatised" after her son was diagnosed with Respiratory Syncytial Virus.

Nick and Vanessa Lachey

Nick and Vanessa Lachey

The 37-year-old television personality admits it was a "traumatic experience" when her and Nick Lachey's son was hospitalised for nearly a week whilst battling the respiratory virus.

She wrote on Instagram: "When I gave birth to my youngest, Phoenix, at 30 weeks, I knew he would need extra care. But I wasn't aware that he was at an increased risk for a common respiratory virus called #RSV due to his under-developed lungs and immature immune system. So when he was hospitalized for six days for severe RSV disease, I was shocked and terrified. I wish I had known more about RSV before this traumatic experience (sic)"

Meanwhile, Nick and Vanessa previously opened up about their marriage and says it hasn't been a "walk in the park" but they're committed to working through their issues.

Nick said: "I think if people make it to seven years of marriage, that's long these days! Any marriage is challenging -- it's certainly not a walk in the park, but we're very committed to each other and to working through those challenges and I'm very confident there's nothing we can't get past. I don't know if there's any truth in the seven-year itch. We've always found a way to keep it interesting. We've been together 12 years, have a beautiful family and are very blessed, and there's just never a dull moment around this house."