Background: A study was done to determine if the apparent medication errors found in the Vaccine Adverse Event Reporting System (VAERS) database are true errors, and if true errors are found, to determine what corrective action was taken. Furthermore, if a true error did not occur, we wanted to determine at what point the misinformation was entered into the system.
Methods: The VAERS database was searched for reports received between July 1, 2001 and June 30, 2002 which had either been classified as "error" or the word "error" appeared in the text of the report. The database was also searched for reports which indicated that the measles-mumps-rubella (MMR), diphtheria-tetanus-pertussis (DTP), diphtheria-tetanus-acellular pertussis (DTaP) or diphtheria-tetanus-pertussis-haemophilus (DTPH) vaccinations had been administered at an age outside of the usual recommendation.
Results: A total of 119 reports of possible errors were found. Follow-up was successful in 102 (86%) cases. Additional information obtained showed that 26 cases were actual medication errors. Seventy-six cases were not actual medication errors; 9 cases were physician decisions, 37 cases were data entry errors and 30 cases were reporter errors.
Conclusion: The nature of the actual errors was similar to those reported previously; wrong inoculum, improper interval, wrong route of administration, and overdose. Many errors could have been prevented by more attention to detail. Remedial action usually consisted of retraining. The new requirement that all medications be barcoded, purchasing products from different manufacturers and segregation of vials may help prevent vial confusion.