As a young person, I began donating blood as soon as I was old enough. It was just what you were supposed to do. And I felt good about it.
About 20 years ago, the United States FDA imposed new restrictions on who can donate blood, in response to fears from the mad cow disease outbreak in the 80s and 90s. At that time, the spread to humans resulted in 200+ cases of the deadly variant Creutzfeldt-Jakob Disease, which was linked to consuming tainted meat from the UK. I lived overseas as a kid, and it just so happens that my situation placed me into the CANNOT DONATE category, making me ineligible to donate blood when the new rules were implemented around 2002. It also rendered ineligible practically any member and family member of the US Armed Forces or US embassy/mission workers that served in Europe in the 1990s if their commissary sourced meat from the UK. So many potential donors were summarily blocked from giving blood!
I learned recently that the FDA finally relaxed those restrictions last year, along with a number of other eligibility criteria, in light of blood shortages during the pandemic lock down. You can see the full announcement here. Through the second half of 2020, individual localities worked to implement the less restrictive rules in their donor screening. As of the end of 2020, my blood donor location, weareblood.org, incorporated the new rules.
I’m happy to report that I resumed my donations today after nearly two decades! It wasn’t easy, it took me about 3 months of contacting the blood bank people to get back on the “eligible to donate” list. As you can imagine, there is a huge backlog of donors who are eligible again and want to donate.

Please consider being a blood donor. There are not many ways ordinary citizens can save lives. This is one.
If you are not sure where to donate in your area, the American Red Cross can help you locate a place near you, see this link.