Sometimes healthcare personnel inadvertently administer the wrong dose of a vaccine to a child or adult patient. This often happens with vaccines that come in both pediatric and adult formulations, such as hepatitis A and hepatitis B vaccines, which are available in both 0.5 mL and 1.0 mL formulations. Routinely used injectable influenza vaccines come in two dosing amounts as well, with 0.25 mL for use in children younger than age 3 years and 0.5 mL for people age 3 years and older. Below is some guidance on what to do when such dosing errors occur, and how to avoid these errors in the future.

If you administer too large a dose

If you’ve administered too large a dose (e.g., you’ve given an “adult” dose to a child) instead of the correct dose of hepatitis A, hepatitis B, or influenza vaccine, inform the patient, parent or guardian of the administration error and document it in the medical record. This dose counts as valid. Although it is unlikely that your patient will suffer any untoward side effects from receiving a “double dose” of vaccine, using larger-than-recommended dosages can result in excessive local or systemic concentrations of antigens or other vaccine constituents. When errors of this nature occur, it is important to assess how the error happened and to implement strategies to ensure they will not be repeated. Administering larger-than-recommended doses of any vaccine does not negate the need for subsequent recommended doses.

If you administer too small a dose

If you’ve administered a pediatric dose or half dose of a vaccine in error, consider the dose invalid and repeat it. Giving less than a full dose might result in inadequate protection. Revaccinate the patient with the appropriate dose according to recommendations specific to inactivated and live-virus vaccines. You may give the additional dose during the same visit if the error is discovered while the patient is still in the office.

If you administer the wrong brand of influenza vaccine

If you’ve administered an injectable influenza vaccine product that is not licensed for use in a child the age of the child you have vaccinated, this is an administration error. In such a case, if you administered the correct dosage to the child, even though it is the wrong product, consider the dose valid and do not repeat it. Inform the patient, parent or guardian of the error and document it in the medical record.

Resources that can help

Here are examples of some strategies you can implement to prevent administering the wrong dose of vaccine:

Finally, remember you can report vaccine administration errors confidentially to the National Vaccine Error Reporting Program, which is part of the Institute for Safe Medication Practices.