. >> reporter: just months ago, honduran immigrant leo castillo was living out his american dream. 43-year-old fun dad with a zest for life. a practical joker known for his sense of humor. an essential worker construction supplies during the pandemic. always counting down the days when he could be back home with his kids. >> i'd be so excited to see him. seeing his location, oh my gosh, he's going to be home in 30 minutes! in the fro whi and hither stay d justau with us, you >> reporter: but a couple months into the pandemic, covid ripped through their washington, d.c. home. first leslie's son, then leslie, both with relatively mild symptoms. but then leo got sick. it wasn't long before he was hospitalized, put on a ventilator. >> one day you get a call, he might only have hours to live? >> reporter: that unwavering faith and tenacity led them to last-chance shot at life i chicago, praying for a double lung transplant. though he's free of covid, the damage to his lungs was done. he'd be only the fourth ever lung transplant patient due to covid in the entire country. >> feeling okay

leo castillo was dying of covid then he became the third-ever covid patient to get a double lung transplantat 43, leo was loving life as a husband and father. active, healthy with his zest for life. and a sense of humor. but in the spring of 2020 covid ripped through his household. by may, he wound up in the hospital put on a ventilator. >> transplant is all should be the option of last resort. >> reporter: though free of covid, the virus essentially destroyed his lungs meaning the organ simply couldn't recover. >> you know, your lungs are pretty badly damaged. >> reporter: but a rare and risky double lung transplant turned out to be his only hope >> you feeling okay? yeah? you feel like you have gotten stronger in the last few days? yeah? >> reporter: dr. bharat of northwestern memorial hospital in chicago, is spearheading the effort. the first to try it on a covid patient in the u.s. and just six days after he was listed for transplant -- there's word of a potential donor. >> take a look at the lungs and give a thumb's up if everything looks fine. >> can you please send me pictures? >> ye