Researchers are finding that the survivors of the 1918 flu epidemic are still producing antibodies to protect against it. This revelation, they say, could help scientists develop prevention methods for deadly outbreaks in the future.

Dr. James E. Drowe Jr. of Vanderbilt University gathered together 32 men and women who were born during or before 1915. After analyzing blood samples, Drowe and his team discovered that every one of them was still producing antibodies to the 1918 strain of the flu. The elderly could prove to be a very good source for new antibodies, researchers say. The global flu pandemic of 1918 killed more than 50 million people.

Researchers aren’t sure whether or not this lifelong immunity is unique to the 1918 strain of influenza. They speculate that the 1918 strain was so powerful that the body’s immune response lasted the rest of a person’s life. It is also possible that survivors were exposed to a weaker strain of the flu before the 1918 outbreak that prepared their immune systems for the pandemic. The findings of their study are published in the August 17 issue of Nature.