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ISMP National Vaccine Errors Reporting Program 2017 Analysis (Part I): Vaccine Errors Continue with Little Change

Although vaccination ranks high among the greatest public health achievements of the twentieth century, the success of any individual vaccine relies on correct and widespread administration to the appropriate patient population. Vaccine errors threaten to undermine the protection immunizations provide and often leave patients inadequately protected against serious diseases such as hepatitis A and B, pertussis, diphtheria, cervical cancer, and many others. An analysis of 575 events submitted to the ISMP National Vaccine Errors Reporting Program (ISMP VERP) between January and December 2017 suggests that errors with vaccines continue to occur. Also, the number of error reports submitted to the ISMP VERP in 2017 increased by more than 100 reports compared to prior years since 2012. The most frequent types of vaccine errors reported during 2017 included:

  • Wrong vaccine (23%)

  • Wrong dose (19%)

  • Expired vaccines or contamination/deterioration (19%)

  • Wrong age (17%)

  • Wrong time or interval (8%)

  • Vaccine/component omission (e.g., only diluent or a single component of a two-component vaccine administered) (4%)

  • Wrong route (2%)

  • Wrong patient (1%)

Healthcare setting, involved providers, and reported harm

Since most vaccines are administered in the outpatient setting, practically all of the reported errors occurred in outpatient medical or public health clinics (54%), doctors’ offices (31%), hospital ambulatory settings (6%), or pharmacies (2%). Only 3% of the errors occurred in hospital inpatient settings, and 4% in other settings. Most of the errors occurred within a family practice (48%) or pediatric practice (27%) setting. More than half (54%) of the errors involved medical assistants. While none of the reported errors caused immediate harm to a patient, absent or improper vaccination may have detrimental effects on individual and public health, leading to disease outbreaks, loss of herd immunity that may propagate an epidemic, costly overvaccination and re-vaccination, and consumer skepticism or refusal of vaccination.

Involved vaccines and contributing factors

Wrong age or dose. The top 10 vaccines involved in reported errors are listed in Table 1, along with the most frequently reported contributing factors. Overall, the vaccines involved in the most frequently reported errors have not changed since 2012, and these errors occurred for many of the same reasons previously noted during analysis of the ISMP VERP data between 2012 and 2016, particularly:

  • Age-dependent formulations of the same vaccine

  • Unfamiliarity with the indicated ages for vaccines

  • Failure to verify the patient’s age before administration

  • Unfamiliarity with the dosing of vaccines

These contributing factors most often led to wrong age or wrong dose errors with DTaP, Tdap, and combination vaccines (31%); influenza virus vaccines (26%); HepA vaccines (23%); HepB vaccines (7%); and MMRV vaccines (4%).

Table 1. Top 10 Vaccines Involved in Reported Errors and their Top Contributing Factors


% of All Vaccine Reports

Top 3 Contributing Factors

Contributing Factor


HepA Hepatitis A Vaccine, Inactivated 11 Age-dependent formulations of same vaccine 30
Vaccine stored above recommended temperature 16
Not familiar with dosing of product 11
DTaP-IPV Diphtheria and Tetanus Toxoids and Acellular Pertussis Adsorbed, and Inactivated         Poliovirus 9 Not familiar with indicated patient ages for product 30
Age-dependent formulations of same vaccine 19
Confusion regarding components of the vaccine 6
Influenza Virus Trivalent, Types A and B 8 Age-dependent formulations of same vaccine 16
Similar brand names 11
Patient chart not checked before administration 9
Tdap Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis Adsorbed 7 Similar vaccine abbreviations 16
Similar generic names 13
Miscommunication of drug order 11
Influenza Virus Quadrivalent, Types A and B 6 Age-dependent formulations of same vaccine 33
Patient age not verified before administration 11
Similar vaccine container labels/packaging 6
HepB Hepatitis B Vaccine (Recombinant) 6 Age-dependent formulations of same vaccine 18
Patient chart not checked before administration 18
Similar generic names 6
MMRV Measles, Mumps, Rubella and Varicella Virus (Live) 6 Similar vaccine container labels/packaging 21
Similar vaccine abbreviations 12
Not familiar with indicated patient ages for product 12
9vHPV Human Papillomavirus 9-valent vaccine (Recombinant) 6 Vaccine stored above recommended temperature 41
Patient chart not checked before administration 13
Not familiar with vaccination interval for product 6
DTaP Diphtheria and Tetanus Toxoids and Acellular Pertussis Adsorbed 5 Routine check for expired products not conducted 16
Age-dependent formulations of same vaccine 13
Patient chart not checked before administration 10
DTaP-IPV/Hib Diphtheria and Tetanus Toxoids and Acellular  Pertussis Adsorbed, Inactivated  Poliovirus and Haemophilus b Conjugate (Tetanus Toxoid Conjugate) 5 Not familiar with how to mix or prepare product 18
Not familiar with indicated patient ages for product 11
Similar brand names 4

One example of a recent dosing error involved ongoing confusion between two of the three available HepB vaccines on the market, ENGERIX-B (10 mcg/0.5 mL; pediatric) and RECOMBIVAX HB (5 mcg/0.5 mL; pediatric). A hospital pharmacy received orders for Engerix-B for newborn infants during a Recombivax HB shortage. While the two brands of the HepB vaccine differ in concentration, the recommended dose in terms of volume is the same (both 0.5 mL for infants, or 10 mcg of Engerix-B and 5 mcg of Recombivax HB). However, the pharmacist, who was more familiar with Recombivax HB (5 mcg/0.5 mL), thought he should only dispense half (0.25 mL) of the vial of Engerix-B (10 mcg/0.5 mL) for each infant’s dose to match the 5 mcg dose of Recombivax HB. Subtherapeutic immunization occurred with several dozen infants before the error was recognized. Prior to this, over a 2-year period at a different hospital, 1,400 infants were given a subtherapeutic dose of Engerix-B (5 mcg, 0.25 mL) and were discharged vulnerable to hepatitis B.

Wrong vaccine. Another group of commonly reported vaccine error contributing factors included similar brand and generic names, abbreviations, and vaccine container labels/packaging. These contributing factors most often led to mix-ups between:

  • Diphtheria, tetanus, and/or pertussis vaccines (Tdap, DTaP, DT, Td, and combination vaccines) (23%)

  • Measles, mumps, rubella, and/or varicella vaccines (MMR [M-M-R II], MMRV [PROQUAD], and varicella [VARIVAX]) (16%)

  • Hepatitis A (HAVRIX and VAQTA), hepatitis B (Engerix-B, Recombivax HB, and HEPLISAV-B), and combination vaccines (TWINRIX and PEDIARIX) (11%)

  • Pneumococcal vaccines (PNEUMOVAX 23 and PREVNAR 13) (10%)


Wrong vaccine errors also continue because the conjugate polysaccharide antigen listed on some vaccine labels is mistaken as the target vaccine name. Vaccines that protect against Haemophilus influenzae type b, meningococcal, and pneumococcal infections are typically connected to polysaccharide antigens that trigger the immune system to respond. The three common proteins used to conjugate polysaccharide antigens include tetanus toxoid, diphtheria, and meningococcal protein. Including the name of the protein used to conjugate the polysaccharide antigens introduces an opportunity for error. These carrier proteins do not induce immunity to tetanus, diphtheria, or meningococcal disease; however, the presence of these words has inferred protection and led to mix-ups.

In one recent example, a medical assistant administered a Haemophilus b conjugate vaccine (PEDVAXHIB) instead of the prescribed meningococcal vaccine (MENACTRA) because the PedvaxHIB vaccine label displayed “[Meningococcal Protein Conjugate]” sandwiched between the unbracketed vaccine generic name, “Haemophilus b Conjugate Vaccine” and the brand name, using the same font type, color, and size. Similar errors in the past have involved the Haemophilus influenzae type b vaccines HIBERIX and ACTHIB, which are tetanus toxoid conjugates; and the other meningococcal vaccine MENVEO and the pneumococcal vaccine Prevnar 13, which are diphtheria conjugates.

Wrong vaccine interval errors. More than half (53%) of all vaccine interval errors were associated with not checking the patient’s chart to confirm the date of the prior vaccine. Additional contributing factors for this type of error included lack of documentation of the prior vaccination in either the patient’s medical record or the vaccine registry (23%), miscommunication of vaccine orders and ambiguous due dates (16%), and unfamiliarity with vaccine intervals (16%). One error report described an event related to a confusing registry report that did not distinguish between vaccine doses due on the day of the clinic visit and doses due at some point in the future, leading to early administration of a HepA vaccine.

The vaccines most frequently involved in wrong interval errors included those that target diphtheria, tetanus, and/or pertussis (26%), HepB (21%), HepA (15%), and the human papillomavirus vaccine 9vHPV (GARDASIL 9) (9%). Some of the reported timing-related vaccine errors can be attributed to the complex Centers for Disease Control and Prevention (CDC) immunization schedules as well as individualized catch-up vaccine schedules, particularly when parents want to alter the CDC-recommended vaccine schedule for their children.

Unnecessary or duplicate vaccinations, omissions, and wrong patient errors. Not checking the patient’s chart or vaccine registry were also selected as common contributing factors associated with duplicate vaccines, omissions, and wrong patient errors, particularly with vaccines that target diphtheria, tetanus, and/or pertussis (34%); influenza virus vaccines (16%); HepA (10%); MMRV (6%); and HepB (6%). Some duplicate doses were administered because the provider inadvertently administered two vaccines containing overlapping components. For example, there were several reports involving the administration of both MMRV and MMR. Reports also noted that numerous patients received a combination vaccine when only one component was needed (e.g., MMRV instead of Varivax alone), or received a single vaccine already contained in a combination vaccine given at the same time (e.g., MMRV and Varivax). Giving just one component instead of the combination vaccine was also reported.

Administering diluents without the active vaccine components or administering one component of two-component vaccines is another type of vaccine omission reported. There are about a dozen vaccines that require reconstitution with specific diluents. Errors have involved administration of a product’s diluent alone, particularly for ActHIB, Varivax, and ZOSTAVAX (zoster vaccine). Also, several vaccines are provided in two-component containers that must be mixed prior to administering the dose. These include an active liquid component that must be used to reconstitute an active powder component. Errors have been reported in which only one component of the two-component vaccine was administered.

Most (77%) of the reported errors of this type involved PENTACEL, which is supplied in two vials, one containing the DTaP-IPV liquid component, and another containing the Hib lyophilized powder component. The active liquid component of the vaccine alone was administered without first mixing it with the active lyophilized powder component. Similar errors have been reported with Menveo. The most frequently reported contributing factors associated with these events included unfamiliarity with mixing and preparing the vaccines (46%) and misleading or similar cartons and containers (15%).

Although wrong patient errors were reported infrequently, preparation of different vaccines or different age-formulations of the same vaccine for more than one patient was most often a contributing factor, particularly when treating multiple patients in the same treatment room. Some of these events also involved unlabeled syringes. In one case, a 15-month-old child received an adult influenza vaccine, and his father received the pediatric influenza vaccine, when both vaccines were prepared and brought into the treatment room for administration. Many of the other wrong patient errors were associated with sibling confusion in which one child received a vaccination intended for another sibling in the same treatment room. However, some of these events were categorized as wrong dose errors if the wrong formulation (adult or pediatric) of the correct vaccine was administered to the wrong sibling. 

Contamination, deterioration, and expiration of vaccines. Most of the reports of vaccines kept outside proper storage temperatures were submitted in clusters from single facilities that had experienced an unintended temperature excursion with a batch of available vaccines. More than half (57%) of these reports involved Gardasil 9 (9vHPV), Havrix (HepA), and BEXSERO (MenB-4C), which all require refrigeration. Expired vaccines were discovered after administration, usually upon documentation.


Although we have learned important information from the error reports submitted to the ISMP VERP, analysis of the 2017 data differs little from previous years’ analyses. Therefore, we plan to take all that we have learned about vaccine errors from our reporting program between 2012 and 2017 and provide recommendations in Part II of this newsletter feature to help providers prepare for immunization initiatives in hospitals and ambulatory clinic settings. Part II will appear in our June 28, 2018 newsletter. While not inclusive of all preparations required for immunization initiatives, these recommendations will be responsive to the specific types of errors reported to the ISMP VERP. We plan to include a checklist of error-prone topics and prevention strategies to cover with staff who will be administering vaccines. The tips will also help facilities evaluate their vaccine practices and staff training programs, even if a targeted immunization initiative is not being planned.