Vaccination Errors Reported to the Vaccine Adverse Event Reporting System 2000-2011

BACKGROUND: Medication errors are an important public health problem and the subgroup of vaccination errors is relatively understudied. We characterized vaccination error reports to the Vaccine Adverse Event Reporting System (VAERS), a U.S. passive surveillance system for vaccine adverse events (AEs).  

METHODS:  Signs and symptoms of AEs described in VAERS reports and reported medical errors are coded using the Medical Dictionary for Regulatory Activities (MedDRA).  We searched VAERS for U.S. reports of vaccination errors from 2000-2011 using 39 MedDRA medical error coding terms and categorized them into 11 error groups.  We performed manual review of selected reports and available medical records.

RESULTS:  Of the 255,528 reports received by VAERS from 2000-2011, we identified 13,137 (5.1% ) vaccination error reports.  The number of annual vaccination error reports increased from 10 reports in 2000 to 1,396 in 2011, peaking at 2,696 in 2008.  Of the vaccination error reports, 8813 (67%) reported the error without any AE while 4,324 (32.9%) documented an AE. Among these reports the most common AEs were injection site erythema (n=583, 13.5%), fever  (n=495, 11.4%) and  injection site pain (n=468, 10.8%).  The most common vaccination error reported was inappropriate schedule (i.e. wrong age, wrong schedule) (n=3,886, 29.6%), most often described for pediatric rotavirus vaccines (n=620, 16%).  The second most common vaccination error was wrong vaccine administered (n=2,693, 20.5%).  In a random sample of 100 reports of wrong vaccine administered, the most common mix-ups involved similar or related vaccines (i.e. Varicella and Zoster, pediatric DTaP and adult Tdap) in vaccination settings that served both children and adults.  We identified an unexpected vaccination error: 25 reports of rotavirus vaccine eye splashes affecting mainly healthcare providers (16 associated with ocular symptoms).  Cluster reports occurring in multiple individuals (range 2-500 persons) at the same vaccination location and date were noted 208 times; the most common error for clusters was expired drug administered.

CONCLUSIONS: Although VAERS data have limitations of passive surveillance, the data show that potentially preventable vaccination errors have occurred since 2000 in individuals and in clusters.   The most common vaccination errors, inappropriate schedule and wrong vaccine, as well as unexpected rotavirus eye splashes, may be prevented with education or packaging changes.  Even though most vaccination errors are not temporally associated with an adverse health event, errors potentially could cause adverse events, incur additional costs, inconvenience patients and impact confidence in vaccination programs.  Prevention strategies should be considered and evaluated.