The Department of Defense Serum Repository has 55.5 million samples from 10 million service members. Almost 900,000 of those samples came from family members who may not even be aware that their blood samples are being kept on file.
The biological material from military family members often ends up in the repository after beneficiaries receive pregnancy care or visit a sexually transmitted infection clinic. The data accompanying those samples are more sparse and so the serum specimens are not as useful for studies, although they are still kept in the repository. Another 4 percent of the samples come from civilians who applied for military service but did not join.