Modern diets, stress, gut issues, and even medications like metformin or antacids can interfere with B12 absorption leaving your body depleted, even if your blood test is normal. What does B12 deficiency feel like
Follow institutional SOPs for receiving, logging, aliquoting, labeling, and disposal
The four forms (vitamins) of B12 are all deeply red colored crystals and water solutions, due to the color of the cobalt-corrin complex (biologically relevant enzyme, it is the "core" of vitamin B12)
However, efficacy against severe disease does appear more durable, with vaccines leading to a ~90% reduction in severe disease at 5 months postvaccination [30, 33]