Mellow yellow is helping one little boy fight an illness that has confined him to a bubble.

Seth Lane, a 5-year-old from Northamptonshire, England, who suffers from a severe combined immunodeficiency often referred to as “bubble boy disease,” started a viral campaign Wednesday, asking Internet users for their support.

Born without enough white blood cells to fight infection, Seth has had to live in a sterile hospital room for more than half his life, and often his parents are barred from having direct contact with him if they’re sick, according to the New York Daily News.

Seth has been awaiting a bone marrow transplant at The Great North Children's Hospital in Newcastle, England, since January, reports the Huffington Post. But recently, his parents, Nik and Leanne Lane, created a video asking people around the world to post a picture of themselves wearing yellow to Twitter, Facebook or Instagram with #WearYellowForSeth.  

"My mummy and daddy will show me all the pictures and print them for my room," Seth said in the YouTube video.  

He also let watchers know he’s a fan of “Fireman Sam,” “Paw Patrol” and of course, the color yellow.

Seth’s family says they are hopeful that a bone marrow transplant will help to rebuild Seth's immune system, but are trying to be realistic, according to their blog, “Our Little Hero.”

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"We did not have a picture of all four of us and I felt like I needed to get one in case we don't get the chance again," Leanne Lane wrote on their blog. "Seth is not guaranteed to get through the next four months."

The video had received more than 2 million views on the family's blog as of Tuesday afternoon, according to BuzzFeed.  

"Our aim with #WearYellowForSeth is to raise awareness and show Seth he is not alone in this," Lane wrote on their blog.  "I wanted to thank everyone for their kind words and support and for sharing Seth's video."