Every blood donor is a lifesaver. But Australian James Harrison is even more so. His blood contains a special antibody that doctors have used to help save the lives of babies with a rare health issue. For the last 60 years, Harrison has regularly donated that blood, and in doing so he has saved many lives — including the life of his own grandchild.

It all started almost 64 years ago, when Harrison was just 14 years old. He needed a risky surgery that involved removing two-thirds of his left lung. During the operation, Harrison needed 13 units of blood to survive. As he recovered, his father explained the extent of his surgery and how the blood donated from strangers had kept him alive. Harrison vowed to return the favor when he reached the legal age to donate his own blood. It's a vow he has kept every week for the last 60 years.

When Harrison gave blood for the first time, doctors soon realized that the teenager's blood contained an antibody to a condition that had cost the lives of thousands of Australian babies every year.

The condition, called Rhesus (or Rh) disease, occurs when a negative blood-type mother conceives a baby that has a positive blood type. Essentially, the mother's blood begins attacking that of the newborn, resulting in brain damage, organ failure and possibly death.

But using a vaccine created from Harrison's blood, doctors are able to prevent any issues that might arise between a mother's blood and that of her baby. This vaccine has saved the lives of more than 2 million babies.

"Australia was one of the first countries to discover a blood donor with this antibody," explained Jemma Falkenmire, spokesperson for the Australian Red Cross Blood Service, in an interview with CNN. "James has effectively helped babies in Australia, but he's [also] helped babies around the world." 

One of the lives saved by Harrison's blood was that of his own grandchild. 

When Harrison's daughter was pregnant with her second child, doctors found an Rh incompatibility between her and her baby. They gave her the vaccine created from the antibodies in Harrison's blood to save her baby's life.

"It makes you feel good that you're put on this Earth and you can do something like that," Harrison said in an interview with Australia's ABC news.

Harrison has been donating the plasma from his blood every week for decades. In about three years (at the age of 81) he will no longer be eligible to donate blood (according to Australian regulations,) so doctors are hoping that another donor with Harrison's special mix of antibodies will step up to take his place.

Check out this CNN video to learn more about Harrison and his amazing gift to the world: