least 1 invalid dose (Butte et al., 2001). A second study, also conducted in the United States, estimated 21 percent of children being overimmunized for at least one vaccine (Feikema et al., 2000). A third study reported on calls regarding vaccines to the National Poison Control Registry in Greece. The estimate of 11 vaccine errors per 1 million immunization doses likely represents significant underreporting since one would have to consider a vaccine dose to be a poisoning to call this registry (Petridou et al., 2004).

Of the two emergency department studies, one focused on global estimates of prescription and administration errors in this setting, and the other on medication errors with respect to antipyretics (see Table C-23). The first study estimated a rate of 100 prescribing errors per 1,000 patients and 39 administration errors per 1,000 patients (Kozer et al., 2002). The second study found that 22 percent of acetaminophen doses ordered were outside of the recommended 10–15 milligrams/kilogram dose (Losek, 2004).

A prospective study analyzed 1,120 patients at two academic pediatric institutions during 1999 using chart, medication order sheet, and medication administration record review, as well as voluntary and solicited reports (Kaushal et al., 2001) (see Table C-24). Twenty-six ADEs were identified—