"In Australia, up until about 1967, there were literally thousands of babies dying each year, doctors didn't know why, and it was very bad", explains Jemma Falkenmire, of the Australian Red Cross Blood Service.
"I hope it's a record that somebody breaks, because it will mean they are dedicated to the cause", Mr Harrison said of his last donation.
Because his blood has unique disease-fighting antibodies, it is used to create an injection which combats rhesus disease - a condition where the blood of pregnant women attacks their unborn babies.
Her blood can then cross the placenta and attack the baby's blood cells, thus causing the baby to have a shortage of blood. In acute cases, the disease can lead to brain damage or even death for the unborn babies.
Soon after donating, he was found to have Rhesus-negative (Rh-) blood and Rhesus-positive (Rh+) antibodies. He said I had (received) 13 units (liters) of blood and my life had been saved by unknown people.
Harrison can no longer donate blood because Australia does not allow donors over the age of 81, but the 81-year-old has vowed to continue helping the medical field by donating samples of his DNA for research, the Atlanta Journal-Constitution reported.
"Every ampule of Anti-D ever made in Australia has James in it", said Robyn Barlow the Rh program coordinator who recruited Harrison, the program's first donor.
When he was 14, Harrison underwent a major chest surgery, receiving blood transfusions that saved his life, according to a statement published by Australian Red Cross Blood Service website. His blood plasma also happens to contain unusually high levels of an antibody used to make a lifesaving medicine for babies.
Harrison was the program's first donor.
After a few years of donating, doctors were shocked to find that his blood contained an antibody that directly neutralizes rhesus disease: a risky condition in which a pregnant woman's blood attacks her unborn child.
'Medications like Anti-D are a life-giving intervention for thousands of Australian mums, but they are only available because men like James give blood'.
"I'd keep going if they let me", Harrison told the Herald.
Anti-D, produced with Harrison's antibodies, prevents women with rhesus-negative blood from developing RhD antibodies during pregnancy. Roughly 17 per cent of pregnant women receive Anti-D, including Harrison's own daughter.
Harrison's blood is valuable because he naturally produces Rh-negative blood, which contains Rh-positive antibodies.
"I think James is irreplaceable for us", says Falkenmire.
That would be more than two million lives, according to the blood service, and for that Harrison is considered a national hero in Australia. The 81 year-old blood donor is one of the 50 people in Australia that has his blood type. "I can't stand the sight of blood, and I can't stand pain".