My kid has -O blood.... used to donate - Red Cross came to the high school... After that they were always sending mail requesting donations. Red Cross always takes a sample checking for iron (i think). It must've been low, but they took the blood anyways. My kid was so sick... the dr said Severe Anemia.... never donated again. So having a - blood type is something they want?

Edited to add, I'm kinda freaked out about this now

My kid has -O blood.... used to donate - Red Cross came to the high school... After that they were always sending mail requesting donations.

Red Cross always takes a sample checking for iron (i think). It must've been low, but they took the blood anyways.

My kid was so sick... the dr said Severe Anemia.... never donated again.

So having a - blood type is something they want?