On May 9, Sunday, a 23-year-old woman in Tuscany, Italy, received six doses of the Pfizer-BionTech vaccine, an incident that should not happen. This was after the attending nurse mistakenly gave her doses equivalent to an entire vial. The vaccine in question requires only two doses, three weeks apart. Authorities are currently monitoring the woman for potential effects of COVID-19 vaccine overdose.
How It Happened
The patient, a graduate student who needed the shot for her clinical psychology program², said she immediately knew something was wrong after the vaccination; the nurse looked visibly distressed and promptly talked to the attending physician.
Dr. Tomasso Bellandi, director of patient security for the northwest Tuscany health authority, explained that a vial of the Pfizer vaccine contains six doses. Before administration, preparation is done by extracting and transferring each dose to individual vials. The vials where they are transferred is where the vaccines are diluted¹.
When the incident occurred, the nurse thought the vials were already diluted. Bellandi described both diluted and undiluted vaccines look transparent, with the same density. “This contributed to the error,” he said¹.
The nurse realized the overdose after seeing five other syringes meant for the vial².
No Adverse Effects So Far
Immediately after being notified of the COVID-19 vaccine overdose, the attending physician started monitoring the patient’s health.
Dr. Antonella Vicenti, the director of infectious disease at Noa Hospital where it all happened, said the patient did not develop a fever or experience pain, save for some discomfort at the injection site¹.
The woman remained in the emergency room for 24 hours, where she received fluids, anti-fever, and ant-inflammatory medicines as preventive measures. She was discharged the following day, Monday.
For now, Dr. Vicenti is confident the patient “will certainly not have side-effects.” However, she doesn’t know what the massive dose will do to the woman’s antibody levels and immunity against COVID-19 in the long run. Noa Hospital said they would regularly monitor the patient’s blood and immune response¹.
Pfizer’s phase 1 and 2 clinical trials showed that participants who received higher doses than recommended didn’t develop any severe adverse reactions³.
It’s Not The First Reported Case of COVID-19 Vaccine Overdose
What happened in Tuscany was not the first reported case of COVID-19 vaccine overdose.
In December of 2020, news broke that eight healthcare workers in an elderly home in Germany received five times the standard dose of the Pfizer vaccine. Four were then sent to the hospital after developing flu-like symptoms⁴.
In April 2021, 77 inmates of the Iowa State Penitentiary received six times the usual Pfizer vaccine dose. Prison officials said none of the inmates needed hospitalization, but some experienced side effects like fever and body aches⁵.
Mistakes In Vaccination Have Other Consequences
Besides the potential health risks, authorities fear that COVID-19 vaccine overdose will fuel the public’s hesitancy towards vaccination.
They also worry about vaccine wastage. With many countries far behind the vaccination program, every dose counts.
Health authorities understand that medical front liners most often reach their limits on duty. And so, lapses do happen. But they also emphasized an overdose should never happen.
