Oh, there is a little problem with the blood mechanic: Since it's 100% random when a patient will come up with that disease, you may get extremely unlucky and get lots of patients needing blood back-to-back. To ease that, there were cabinets where you could store blood for later use, but even so, RNG can definitely screw you up.
Taking blood from a patient that needs blood is considered a medical error in the game, so the result was intended, but yeah I should've thought of a better randomized distribution (one that ensured at least some patients with other diseases first to let you stock up blood)
Thank you so much for playing!