Additional risk of age-related mix-ups now that our youngest patients are eligible for COVID-19 vaccines

Problem: With the expanded emergency use authorization (EUA) for patients as young as 6 months old, there are now three different age groups, not just two, that are eligible for the Pfizer-BioNTech and Moderna coronavirus disease 2019 (COVID-19) vaccinations. Similar to the mix-ups that occurred between the Pfizer-BioNTech vaccines for children 5 through 11 years old and for individuals 12 years and older, it is predictable that we will see mix-ups between these three age groups with both the Pfizer-BioNTech and the Moderna vaccines. In the past, some individuals 12 years and older received the Pfizer-BioNTech vaccine formulation and dose intended for children 5 to 11 years old, resulting in underdoses. Or children who were 5 to 11 years old received the formulation and dose intended for individuals 12 years and older, resulting in overdoses. Similar errors could happen with the new vaccines for our youngest patients. We do not want mix-ups between these vaccine formulations to raise concerns and undermine public health efforts to have as many children vaccinated as possible, even though these errors are not expected to cause serious adverse events.

Moderna Vaccine

The Moderna EUA vaccine (Table 1) comes as a two-dose series administered 1 month apart to individuals 6 months through 17 years. Previously, the vaccine had been authorized for use in adults 18 years and older. The vaccine was also authorized to provide a third primary series dose at least 4 weeks following the second dose for individuals 6 months and older who have certain kinds of immunocompromise.

Table 1. Moderna COVID-19 Vaccine Formulations

^{† May not be available currently}

Pfizer-BioNTech Vaccine

The Pfizer-BioNTech EUA vaccine (Table 2) comes as a three-dose series for children 6 months through 4 years in which the initial two doses are administered 3 weeks apart, followed by a third dose administered at least 8 weeks after the second dose. Previously, the vaccine had been authorized for use in individuals 5 years and older as a two-dose primary series. The vaccine was also authorized to provide a third primary series dose at least 4 weeks following the second dose for individuals 5 years and older who have certain kinds of immunocompromise.

Table 2. Pfizer-BioNTech COVID-19 Vaccine Formulations  

According to the Fact Sheet, vaccine vial labels for the youngest age group may state “Age 2y to < 5y” or “Age 6m to < 5y,” and carton labels may state “For age 2 years to < 5 years” or “For age 6 months to < 5 years.” These vaccines can be used for children 6 months through 4 years old (www.ismp.org/ext/936). However, locations that receive these vials may find it confusing and mistakenly believe the formulation labeled “2y to < 5y” cannot be used for children younger than 2 years. Also, we do not recommend using the “<” or “>” signs, which are sometimes confused to mean the opposite.

Children who will turn from 4 years to 5 years old between any doses in the Pfizer-BioNTech’s COVID-19 vaccine primary series may adhere to either of the following dosing schedules:

• Two-dose primary series (10 mcg) with the 5 through 11 years vaccine

• Three-dose primary series with the vaccine authorized for use in children 6 months through 4 years of age (3 mcg); the second or third dose may be with the vaccine for ages 6 months through 4 years or with the vaccine for 5 years through 11 years of age.

Safe Practice Recommendations: If clinics, physician practices, or pharmacies administer adult and/or pediatric COVID-19 vaccines, consider the following recommendations, paying particular attention to these confusing issues:

• The Moderna vaccines for children 6 months through 5 years, and for 6 years through 11 years, both have a dark blue cap and an age range that starts with the number “6” on the label. Also, the vial with the purple border only lists the indication for a booster dose, but it is currently the only vaccine intended for use in children 6 years through 11 years.

• The Pfizer-BioNTech vaccines for children 6 months through 4 years and for 5 years through 11 years both require a volume of 0.2 mL for each dose (3 mcg and 10 mcg, respectively) but are provided in different concentrations. Also, the primary series for children 6 months through 4 years requires three doses, while the primary series for children 5 years through 11 years requires only two doses.

Segregate storage. In refrigerators and freezers, store the vaccine formulations apart from one another in separate plastic bins properly labeled with the corresponding age group. Differentiate the bin labels with colors that align with the vial label color, keeping in mind that purple may be the label color for both the Pfizer-BioNTech vaccine for patients 12 years and older, and the Moderna vaccine for children 6 years through 11 years.

Verify identity, age, and vaccine(s) requested. When checking in a patient who is scheduled to receive a vaccine(s), ask the parent, caregiver, or patient to provide at least two patient identifiers—their full name and date of birth. Verify the patient’s actual age with the patient, parent, or caregiver, and be sure to ask which vaccine(s), including the brand, they have requested. Repeat this process immediately prior to vaccination.

Verify the vaccine history. Prior to vaccine preparation, check the history on the patient’s vaccine card, the patient’s medical record, and the immunization information system to confirm which COVID-19 vaccines have been administered previously and when.

Label syringes. Clearly label all syringes. To facilitate labeling, print labels for each patient or provide practitioners who prepare the vaccines with strips of preprinted labels that differentiate the formulations and dose for each of the three age groups.

Employ barcode technology. During preparation and administration, use barcode scanning to confirm the correct vaccine.

Vaccinate one patient at a time. Only bring the intended and labeled vaccine syringe(s) for one patient into the vaccination area. Vaccinate one patient at a time.

Engage the patient. Involve the parent, caregiver, or patient in verifying the vaccine, formulation, and dose by reading the label to confirm the correct vaccine.

Document the vaccine(s). Document the lot number and date of manufacture prior to vaccine administration, and document administration afterwards in the patient’s profile, on vaccination records, and via state or other immunization information systems.

Report vaccine errors. Report vaccine errors internally as well as to the Vaccine Adverse Event Reporting System, which is mandatory for COVID-19 vaccines available under an EUA. ISMP also asks providers to report vaccine errors to the ISMP National Vaccine Errors Reporting Program.

Additional resources. For details on immunization schedules, please review the Centers for Disease Control and Prevention (CDC) resource, COVID-19 Vaccine Interim Immunization Schedule for 6 Months of Age and Older. Also, Immunize.org has compiled a tool that organizes information about US COVID-19 vaccines and provides links to dosing guidance, Fact Sheets, package inserts, storage and handling, and preparation and administration. This resource is updated at least monthly.

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^{Institute for Safe Medication Practices (ISMP). Additional risk of age-related mix-ups now that our youngest patients are eligible for COVID-19 vaccines. ISMP Medication Safety Alert! Acute Care. 2022;27(13):3-5.}