It is actually about 0.30 ml, corresponding to the quantity used for 4 doses of Pfizer-Biontech vaccine, the dosage injected by mistake on Sunday 9 May to the 23-year-old clinical psychology trainee. The novelty emerged during the internal audit carried out by the ASL Toscana northwest and ended yesterday evening (May 10) at the Apuane hospital in Massa, during which the bottle used for vaccination was carefully analyzed. and the exact quantity of vaccine solution still present was measured (about 0.15 ml). In fact, the vial originally contains 0.45 ml of serum. The fact that the amount of vaccine injected was just over 4 doses is important because the experiment carried out by Pfizer to identify the consequences of the overdose had come to test a quantity of 4 doses of active ingredient inoculated at the same time, without which The internal audit, which involved all the professionals linked to the story, confirmed – explains the ASL – the dynamics already hypothesized in the previous hours: the nurse did not insert the physiological solution in the vial, she did not he then performed the dilution step and aspirated the quantity necessary to prepare a dose with the precision syringes provided by the company pharmacy. It was therefore a “cognitive slip”, specifies the ASL, in the vaccine preparation phase , which has contributed to a problem of counting and setting up the syringes at the time of preparation of the s vaccine eduta, in a routine activity at high volumes and with pressure due to the need for strict compliance with the times.The Company is working to learn from what happened and further strengthen the barriers aimed at the prevention of possible human errors, for the quality of vaccination services and safety of patients and operators. The young trainee yesterday returned to her home, discharged (given the absence of side effects) after 24 hours of observation in the hospital. She is fine but is still kept under strict control, always in connection with the Careggi Immunology facility.