A 2-component vaccine is any vaccine with two components (i.e. vaccine and specific diluent; vaccine liquid component and vaccine powder component) provided by the manufacturer in physically separate containers that require mixing prior to administration.

When 2-component vaccine errors occur, it results in only one of the two components being administered. This leads to lack of patient protection from preventable disease, need to revaccinate, and an increase in associated healthcare costs.

The three 2-component vaccines with the most reported reconstitution errors in the Institute for Safe Medication Practices (ISMP) National Vaccine Errors Reporting Program (VERP) and US Food and Drug Administration (FDA) Vaccine Adverse Event Reporting System (VAERS) are Pentacel® (DTaP, Polio, Haemophilus influenzae type b), Menveo® (meningococcal), and ActHIB® [H. influenzae type b (Hib)].

Manufacturers should design labeling and packaging of vaccines to provide ease of storage and fail-safe preparation of vaccines to prevent 2-component vaccine errors.

Implementing risk-reduction strategies, such as training healthcare professionals and affixing storage bin labels, remind healthcare professionals to mix the 2-components and facilitate appropriate administration.