Within a few days, Heather Griffin went from dropping her dad off at a hospital to dropping off her mother there too -- then, one after another, within 24 hours, both her parents were transferred into the ICU and put on ventilators.

"If I would have lost either one of them ... it would have been like half my world gone," Griffin told ABC News’ Kaylee Hartung.

Connie and Marvin Griffin have been married for 33 years. They rarely leave each other’s side, and after raising two kids, nothing brings them more joy these days than being grandparents to Heather’s four-year-old daughter.

With both of them intubated and in the ICU, a possible lifeline emerged when the family needed it most: experimental convalescent plasma therapy.

The immune system produces antibodies to help fight viruses, and three to four weeks after a person recovers from COVID-19 their plasma can be drawn to see if contains those coveted cells. If it does, the antibodies can be injected into someone else who may be struggling to produce them.

The treatment was first used to combat the Spanish Flu in 1918.

"Thus far with plasma and from all the history that we have seen with this therapy, it appears that it is much more likely to help than it is to harm when used correctly," said Doctor Roberto Colon, who leads the team pioneering this possible treatment at Premier Health Systems in Dayton, Ohio.