A woman in Italy accidentally received six doses of the Pfizer-BioNTech COVID-19 vaccine at one time, according to news reports.
The 23-year-old woman did not experience any serious side effects from the vaccine overdose, according to CBS News.
The incident occurred on May 9 at the Noa Hospital in Tuscany, Italy. The nurse administering the vaccine accidentally injected the woman with an entire vial of the Pfizer-BioNTech vaccine. Each vial contains six doses.
The error occured because the nurse apparently thought that the vial she was injecting had already undergone a necessary dilution step. Before the vaccine can be administered, each of the six doses is taken out of the original vial and put into a new vial, where the dose is diluted.
“She thought that the dilution had taken place,” Dr. Tommaso Bellandi, director of patient security for the northwest Tuscany health authority, told CBS News. “They are both transparent liquids of the same density. Unfortunately, this contributed to the error.”
The nurse quickly realized her mistake, and the patient was monitored for 24 hours at the hospital. She was given fluids and fever-reducing medications as a preventive measure.
The only side effect the woman experienced was pain at the injection site. She was released from the hospital on May 10.
The hospital has launched an investigation into the error.
Several other cases of COVID-19 vaccine overdoses have made headlines in recent months, including the case of a 91-year-old man in Ohio who went into shock after he received two COVID-19 vaccine doses in one day.
And in April, 77 inmates at the Iowa State Penitentiary in Fort Madison each received up to six times the normal dose of the Pfizer-BioNTech vaccine due to human error, according to the Des Moines Register.
None of the inmates required hospitalization, but some experienced sore arms, body aches and fevers, the Register reported. The two nurses who were administering the vaccine at the prison have been placed on leave during an investigation into the incident, officials said.