Inadequate injection techniques, particularly the failure to aspirate, can lead to intravenous administration of vaccines instead of the intended intramuscular delivery. Aspirating, which involves pulling back on the syringe plunger to check for blood in the needle, is crucial to avoid accidental injection into a vein. If blood is observed, the needle should be advanced further to ensure it is not within a blood vessel. However, guidelines discouraged this practice to prevent vaccine hesitancy, resulting in a percentage of unintended intravenous injections. Such mistakes can lead to a rapid entry of vaccine components into the bloodstream, potentially causing significant harm, including complications that could lead to fatalities. The oversight in standard injection protocols represents a critical risk factor in vaccination procedures that could have serious health implications.