This document is intended to assist healthcare providers by providing an approach to managing COVID-19 vaccines that are administered in a manner that differs from the BC Immunization Manual guidelines (referred to as vaccine administration errors). This document builds on guidance developed by the Public Health Agency of Canada's Managing COVID-19 vaccine administration errors or deviations and the CDC's Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States. There is limited evidence to guide the management of these situations. This document provides guidance only. Health authority protocols may differ from this guidance document and clinical judgement in particular situations may also result in different management decisions than outlined below. Note that this document is to be used only to manage errors that have already occurred. The guidelines within the BC Immunization Manual should be followed when administering COVID-19 vaccines to prevent errors or deviations from occurring. The following will be addressed in this document:Administration error Interim guidance on how to consider the dose and recommended action Site/route Guiding Principle: COVID-19 vaccines should be administered intramuscularly. The vastus lateralis (anterolateral thigh) is recommended for children less than 1 year of age. The vastus lateralis or the deltoid muscle can be used for toddlers and older children. The deltoid is often selected as the injection site in these age groups as temporary muscle pain in the vastus lateralis muscle post-vaccination may affect ambulation. The deltoid muscle of the arm is the preferred injection site in adolescents and adults. When selecting a site, it is important to consider available muscle mass. Clients administered a vaccine in an incorrect site or by an incorrect route should be informed of the potential for local and systemic adverse events. Incorrect site (i.e., site other than the deltoid muscle or vastus lateralis as appropriate for age) Consider the dose valid. Incorrect route (e.g., subcutaneous) Consider the dose valid.Use at a younger age than authorized by Health Canada and/or recommended by NACI Consider the dose valid. Receipt of a WHO EUA qualified COVID-19 vaccine not authorized in Canada (e.g., Sinovac, Sinopharm, Covaxin) at < 18 years of age for one or more doses. Consider the dose valid.Guiding Principle: Doses given longer than the recommended interval: While recommended intervals are optimal, doses delayed beyond the recommended interval are considered valid.# 
- Steps to be taken after an error is recognized Steps to be taken after an error is recognized Following the identification of an inadvertent vaccine administration error, healthcare providers should:
- Inform the recipient of the vaccine administration error as soon as possible after it is identified. The recipient should be informed of any implications/recommendations for future doses, and possibility for local or systemic reactions and impact on the effectiveness of the vaccine (if applicable and known). - Report all errors or near miss incidents in accordance with the institutional medication error or professional body's reporting process, including the BC Patient Safety Learning System (PSLS). - If an inadvertent vaccine administration error results in an adverse event following immunization (AEFI), complete the appropriate AEFI Case Report Form found on the Adverse Events Following Immunization page and submit it to the local public health authority. Information on AEFI reporting can be found in the BC Immunization Manual, Part 5 -Adverse events Following Immunization. - Determine how the vaccine administration error occurred and implement strategies to prevent it from happening again. - As with usual practice, when managing errors and deviations, inquire about the client's history of adverse events following vaccination. If they experienced a significant local or systemic reaction, base your decision to offer subsequent doses on a case-by-case basis in consultation with the Medical Health Officer and/or in consultation with an allergist/immunologist. - If the client who had a repeat dose following an invalid dose requires a subsequent dose in the initial series or a booster, give it with a recommended age-appropriate dosage and product. Count the interval from the repeat dose. - Additional resources on vaccine administration practices can be found in the BC Immunization Manual, Appendix B -Administration of Biological Products.
Doses given earlier than the minimum interval: Doses given too close together may result in a suboptimal immune response due to: (1) Less than optimal time to allow for the immune response to mature between doses; and (2) Antibodies produced to the early dose may interfere with the antibody response to the later dose.
For information on recommended and minimum intervals, refer to the respective product pages in the BC Immunization Manual, Part 4-Biological Products, COVID-19 Vaccines.

# Type Administration error
Interim guidance on how to consider the dose and recommended action Subsequent dose of COVID-19 vaccine within the primary series administered prior to the minimum interval.
If the dose was administered at less than the minimum interval, consider the dose invalid and repeat at the recommended interval (counting from the date of the invalid dose). 1 A booster dose of COVID-19 vaccine administered prior to the minimum interval from the last dose of COVID-19 vaccine.
If 8 weeks has passed since the last dose (i.e., primary series or preceding booster) and the current booster dose, consider the current booster dose valid.
If less than 8 weeks has passed since the last dose (i.e., primary series or preceding booster) and the current booster dose, consider the current booster dose invalid and repeat the booster dose 6 months from the invalid dose.

# Higher than authorized dose administered
Guiding Principle: Doses that are higher than authorized are considered valid. The client should be advised of the potential for local and systemic adverse events.
Adult dose provided to a child resulting in a higher than authorized dose. For example a full adult dose of 0.3 mL (30 mcg) Pfizer Bivalent (adult/adolescent formulation) provided to a 5 year old for which a (10 mcg) dose was required.

# Consider this dose valid.
Partial adult dose provided to a child resulting in an equivalent or higher than authorized dose. Examples include:
- 0.2 mL of the Pfizer Bivalent adult/adolescent formulation (i.e., 20 mcg) provided to a 5 year old (rather than the recommended 10 mcg dose).
Consider this dose valid.

# Type Administration error
Interim guidance on how to consider the dose and recommended action - 0.1 mL of the Pfizer Bivalent adult/adolescent formulation (i.e., 10 mcg) provided to a 5 year old (for whom a 10 mcg dose is recommended).

# Less than authorized dose, product or schedule error based on age
(see Diluent section below for specific information regarding Pfizer-BioNTech and the diluent)

# Guiding Principle:
Client should be immunized with the age-appropriate product based on age at presentation. When a client transitions to a different age within the primary series or booster dose, the age-appropriate product based on age at presentation is given.
Lower than the authorized doses may result in a sub-optimal response and may need to be repeated (depending on the product and the age). For complete information on authorized doses per product by age, see the respective product pages, within the BC Immunization Manual, Part 4-Biological Products, COVID-19 Vaccines.
If a repeat dose is indicated, inform the client of the potential for local and systemic adverse events with the repeat dose.
Less than a full dose (dose unknown) was administered (for example, leaked out, equipment failure, client pulled away)
If less than a full dose is administered or the proportion of the dose administered cannot be estimated, consider the dose invalid.
Administer a full repeat dose as soon as the error is recognized. If this is the same clinic day as the invalid dose, use a separate anatomic injection site whenever possible (e.g., different limb).
Children 6 months to 11 years of age Exception to the guiding principle: For Moderna Spikevax, the age appropriate dose for children 6 to 11 years is 50 mcg. For error management, a 25 mcg dose is considered valid for a 6 year old who started the series at 5 years of age. For children starting the series at 6 years of age and for children 7 to 11 years of age, a dose less than 50 mcg is considered invalid. Pfizer-BioNTech Comirnaty 3 mcg dose administered to a child 5 to 11 years (rather than the Consider this dose invalid.

# Type
Administration error Interim guidance on how to consider the dose and recommended action recommended 10 mcg dose) as part of a primary series, or as a booster dose.
Administer a full repeat dose as soon as the error is recognized. If this is the same clinic day as the invalid dose, use a separate anatomic injection site whenever possible (e.g., different limb). 2
Moderna Spikevax 25 mcg dose administered to a 6 year old child who started their primary series at 5 years of age with an age appropriate dose.
Consider this dose valid.
- However, if the error is discovered in time, an additional dose of Moderna Spikevax 25 mcg may be offered on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the additional 25 mcg cannot be given on the same clinic day, do not give an additional dose.
Moderna Spikevax 25 mcg dose administered to a 6 year old child who started their primary series at 6 years of age (rather than the recommended 50 mcg dose).
Consider this dose invalid.
- If the error is discovered in time, an additional dose of Moderna Spikevax 25 mcg may be offered on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the additional 25 mcg cannot be given on the same clinic day, offer a full ageappropriate dose as soon as the error is identified. 2
Moderna Spikevax 25 mcg dose administered to a child 7 to 11 years (rather than the recommended 50 mcg dose).
Consider this dose invalid.
- If the error is discovered in time, an additional dose of Moderna Spikevax 25 mcg may be offered on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the additional 25 mcg cannot be given on the same clinic day, offer a full ageappropriate dose as soon as the error is identified. 2

# Type Administration error Interim guidance on how to consider the dose and recommended action
Adolescents 12 to 17 years of age Exception to the guiding principle: For Moderna Spikevax, the age appropriate dose for adolescents 12 to 17 years of age is 100 mcg within the primary series. However, if a 12-17 year old inadvertently receives a 50 mcg dose of Moderna Spikevax, it is considered valid. Any dose less than 50 mcg is considered invalid.
Pfizer-BioNTech Comirnaty 10 mcg dose administered to individual 12 to 17 years of age (rather than the recommended 30 mcg dose) as part of a primary series, or as a booster dose.
Consider this dose invalid.
Administer a full repeat dose as soon as the error is recognized. If this is the same clinic day as the invalid dose, use a separate anatomic injection site whenever possible (e.g., different limb). 2
- NOTE: If the invalid dose was a booster dose, offer an age-appropriate bivalent COVID-19 mRNA vaccine.

# NOTE:
Any 10 mcg doses that were previously validated prior to October 28, 2022 can remain valid in the Provincial Immunization Registry.
Moderna Spikevax 50 mcg administered to an individual 12 to 17 years of age (rather than the recommended 100 mcg dose) for any or all dose(s) of the primary series.
Consider the dose(s) valid.
- However, if the error is discovered in time, an additional dose of Moderna Spikevax 50 mcg may be offered on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the additional 50 mcg cannot be given on the same clinic day, do not give an additional dose. Moderna Spikevax 25 mcg dose administered to an individual 12 to 17 years of age (rather than the recommended 100 mcg dose) as part of the primary series.
Consider the dose invalid.
Administer a full repeat dose as soon as the error is recognized. If this is the same clinic day as the invalid dose, use a separate anatomic injection site whenever possible (e.g., different limb). 2

# Type
Administration error Interim guidance on how to consider the dose and recommended action - NOTE: Consider offering a full ageappropriate dose of Pfizer-BioNTech Comirnaty (30 mcg) (which is the preferred product for those 12 to 17 years of age).
Moderna Spikevax 25 mcg dose administered to an individual 12 to 17 years of age (rather than the recommended 50 mcg dose) for a booster dose.
Consider the dose invalid.
However, if the error is discovered in time, the repeat dose can be given on the same clinic day:
- If offering Pfizer-BioNTech Comirnaty bivalent vaccine, 30 mcg can be given in a separate anatomic injection site whenever possible in a separate anatomic injection site (e.g., different limb).
- If offering Moderna Spikevax bivalent vaccine, a 25 mcg dose can be given in a separate anatomic injection site whenever possible (e.g., different limb)
If the dose cannot be given on the same clinic day, offer a full age-appropriate bivalent booster dose as soon as the error is identified. 2

# Adults 18 years of age and older
Exception to the guiding principle: For Moderna Spikevax, the age appropriate dose for adults 18 years of age and older is 100 mcg within the primary series. However, if an adult inadvertently receives a 50 mcg dose of Moderna Spikevax, it is considered valid. Any dose less than 50 mcg is considered invalid.
Pfizer-BioNTech Comirnaty 10 mcg dose administered to an individual 18 years of age (rather than the recommended 30 mcg dose) for a primary series or booster dose.
Consider the dose invalid.
Administer a full repeat dose as soon as the error is recognized. If this is the same clinic day as the invalid dose, use a separate anatomic injection site whenever possible (e.g., different limb). 2

# Type Administration error
Interim guidance on how to consider the dose and recommended action
- NOTE: If the invalid dose was a booster dose, offer an age-appropriate bivalent COVID-19 mRNA vaccine.
Moderna Spikevax 50 mcg administered to an individual 18 years of age (rather than the recommended 100 mcg dose) for any or all dose(s) of the primary series.
Consider the dose valid.
- If the error is discovered in time, offer 50 mcg of the monovalent Moderna Spikevax vaccine on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the additional 50 mcg of Moderna Spikevax dose cannot be given on the same clinic day, do not give an additional dose.
Moderna Spikevax 25 mcg administered to an individual 18 years of age (rather than the recommended 50 mcg dose) for the booster dose.
Consider the dose invalid.
- However, if the error is discovered in time, offer a 25 mcg dose of Moderna Spikevax bivalent booster dose on the same clinic day in a separate anatomic injection site whenever possible (e.g., different limb).
- If the dose cannot be given on the same clinic day, offer a full age-appropriate bivalent COVID-19 mRNA vaccine as soon as the error is identified. 2

# Bivalent product error

# Guiding principle:
The primary series is provided with a monovalent formulation, as the bivalent formulations are not approved for doses in the primary series.
An individual receives a bivalent vaccine for one or all doses of the primary series.
Consider this a valid dose.
An adult receives a 0.5 mL (50 mcg) dose of Moderna Spikevax 6 months to 5 year vaccine rather than the recommended Moderna Spikevax bivalent booster dose (50 mcg).
Consider this a valid dose. A 50 mcg dose of a monovalent product is considered a valid booster.
While the monovalent booster dose will boost their immunity and is likely to provide significant protection against hospitalization Type Administration error Interim guidance on how to consider the dose and recommended action and severe disease, an age-appropriate bivalent product may be provided at an interval of at least 8 weeks.
An individual receives an ageappropriate monovalent vaccine instead of a bivalent vaccine for a booster dose.
Consider this a valid dose.
For individuals 5-11 years of age: NACI is currently only recommending one booster dose after the primary series. The client and/or parent/guardian should be reassured that the monovalent booster dose will boost their immunity and is likely to provide significant protection against hospitalization and severe disease, and no recommendation for re-vaccination. However, if the parent/ guardian requests a repeat dose with a bivalent product, an age-appropriate bivalent product may be provided at an interval of at least 8 weeks.
For individuals 12 years of age and older: While the monovalent booster dose will boost their immunity and is likely to provide significant protection against hospitalization and severe disease, an age-appropriate bivalent COVID-19 booster dose may be provided at an interval of at least 8 weeks.

# Storage and handling
Guiding Principle: Storage and handling errors or deviations require individual consideration based on the particular circumstances, in consultation with the BCCDC Pharmacy and based on clinical judgement. If deemed to be invalid, a repeat dose may be given as soon as possible at a different site. Inform the recipient of the potential for local and systemic adverse events For information on Storage and Handling refer to the respective product pages in the BC Immunization Manual, Part 4-Biological Products, COVID-19 Vaccines. 

# Reconstitution error (Pfizer-BioNTech only)
Guiding Principle: Reconstitution errors may require individual consideration based on the particular circumstances, in consultation with the BCCDC Pharmacy and based on clinical judgement. If deemed to be invalid a repeat dose may be given as soon as possible at a different site. Inform the recipient of the potential for local and systemic adverse events.
For information on diluent volume per product, refer to the respective product pages in the BC Immunization Manual, Part 4-Biological Products, COVID-19 Vaccines.
Incorrect diluent type (e.g., sterile water instead of 0.9% sodium chloride for Pfizer dilution) Contact BCCDC Pharmacy for guidance. If BCCDC provides information suggesting that the dose be considered invalid and if that seems appropriate based on clinical judgement, a repeat dose may be given as soon as possible in in a separate anatomic injection site whenever possible (e.g., different limb).
ONLY diluent administered (i.e., sterile 0.9% sodium chloride)
Inform the recipient that no vaccine was administered. Administer the authorized (appropriately diluted) dose as soon as

# Type
Administration error Interim guidance on how to consider the dose and recommended action possible in in a separate anatomic injection site whenever possible (e.g., different limb).
Too much diluent administered resulting in a lower than authorized dose.
Consider this an invalid dose. Administer a full repeat dose immediately in a separate anatomic injection site whenever possible (e.g., different limb).
No diluent or less than the recommended diluent, resulting in higher than the authorized dose.

# Consider this dose valid.
Inform the recipient of the potential for local and systemic adverse events.

# More or less than authorized number of doses obtained from vial
Guiding Principle: Depending on the type of supplies used (e.g., low dead volume syringe) the number of doses obtained from vials may vary. As long as the correct volume was drawn up per dose (and the correct amount of diluent was used, if applicable), the doses are valid.