The older population are more likely to be B12 deficient. B12 and its associated co factors are essential for the production of hemoglobin. I significant percentage of the population are unaware they have B12 deficiency due to failings in the testing regime available through failings in healthcare systems. Vegetarians and vegans are susceptible due to dietary restrictions. The hospital to which I was taken did not test for B12 deficiency on admission. If the hospital are stupid enough to use nitrous oxide in their covid ventilators its no wonder that people died. Covid depletes Vitamin B12 . Nitrous oxide depletes vitamin B12. PPI's (Omeprazole and the like also deplete B12) Its a perfect storm which in the panic of the pandemic swept through multiple health services world wide. I was lucky. I knew I was b12 deficient, and despite having Covid Pneumonia, Bacterial Pneumonia and a fungal infection my consultant actually listened to what I was telling him and gave me my overdue injection of Hydroxocobalaminafter threatening me with 'A ventilator or palitive care' . The ventilator was not needed as within 24 hours the decline in my O2 sats reversed and within 5 days I was back on a normal , non covid ward. I was called 'the miracle patient of ICU' by the hospital staff. All the evidence is available in my extensive hospital records.