But now, the Saugus resident is victorious, having defeated the virus.
There was a well-deserved round of applause for Mastrobuono as he was discharged this week from Henry Mayo Newhall Hospital in Santa Clarita, where he spent nearly two weeks with COVID-19. He was intubated with a ventilator helping him breathe.
"It's slow getting back," he said. "It's almost like learning how to walk all over again."
Coronavirus symptoms, tips amid COVID-19 outbreak
Coronavirus symptoms, tips amid COVID-19 outbreak
The odds were not in his favor. About one in 10 patients his age don't survive COVID-19, but far fewer for those placed on a ventilator.
"We're looking at maybe a 60% mortality rate, but again these are our sickest patients," said Bud Lawrence, MD, Medical Director of Henry Mayo's Emergency Department.
Mastrobuono was certainly one of them.
"I just remember waking up in the hospital," he said.
"He was very incoherent. I could tell he wasn't quite himself and the fever came back that afternoon on the 1st and Tylenol did not bring it down," recalled Mastrobuono's wife Becky. "And that's when I called 911."
Becky Mastrobuono took him to the hospital April 1 when his fever spiked to more than 103. She was there to greet him outside the hospital this week, the first time she had seen her husband in two weeks.
"The sendoff that Henry Mayo gave him was very emotional and very touching," she said.
"The people at Henry Mayo were fantastic," Jim said. "Took good care of me... makes me want to cry."