Mpox vaccination clinical resources: Managing vaccine administration errors or deviations

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Preamble

This guidance document is for health care providers. It offers an approach to managing the Imvamune vaccine that is administered in a manner that differs from the recommendations of the manufacturer as authorized by Health Canada and/or the National Advisory Committee on Immunization (NACI). These are referred to as vaccine administration errors or deviations. This document builds on guidance developed by:

We also received input from the Canadian Immunization Committee and NACI.

For complete NACI advice, please see the following:

There is limited evidence to guide the management of these situations. This document provides guidance only. Note that provincial and territorial protocols may differ from this guidance document. Clinical judgment is necessary for making appropriate decisions regarding vaccine administration errors and deviations and may result in management decisions that differ from those outlined in this guidance.

Note that this document should be used only to manage errors or deviations that have already occurred. In order to prevent errors or deviations from occurring, please follow provincial/territorial guidance, the product monograph and recommendations from NACI statements and publications when administering Imvamune. Training, educational resources, policies and procedures and oversight are useful tools to support the prevention of errors and deviations.

The term "valid" in this document refers to a dose that is considered acceptable for the purposes of managing an error or deviation.

What to do after an error or deviation is detected

If an inadvertent vaccine administration error or deviation is found, health care providers should:

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 an allergist, immunologist or another appropriate physician.

Refer to the Canadian Immunization Guide smallpox and mpox vaccine chapter for information on vaccine administration (including simultaneous administration), safety and adverse events.

Serologic testing to assess vaccine-induced immunity is generally not recommended to respond to errors or deviations in vaccine administration. Health care providers are encouraged to contact their local public health authority and/or their provincial or territorial public health laboratory for advice if considering using serology to investigate an error or deviation.

For other resources on vaccine administration practices, please consult the Canadian Immunization Guide.

Type of administration errors or deviations: Guiding principles, recommended actions, and examples

Site or route errors

Guiding principles

Imvamune is generally administered subcutaneously (SC), with the recommended sites being the triceps or the anterolateral thigh areas. In case of vaccine shortages, the intradermal route can also be used.

See the route, site and technique for vaccine administration in the Vaccine administration practices: Canadian Immunization Guide chapter.

See dose, route of administration and schedule in the Smallpox and mpox vaccine: Canadian Immunization Guide chapter.

Incorrect sites and routes are considered valid if an appropriate dose was used.

Examples

Incorrect site

If a site other than the triceps or anterolateral thigh area is used for subcutaneous administration:

  • Do not repeat dose.
  • Inform the recipient (and parent or guardian) of the error or deviation and of the potential for local and systemic adverse events.
Incorrect route

If an incorrect route (for example, intramuscular administration) was used (with the correct dose (0.5 mL)):

  • Do not repeat dose.
  • Inform the recipient of the potential for local and systemic adverse events.

If an incorrect route with too low a dose was used, see section below ("A dose that is too low administered by a route other than the subcutaneous route").

Dose errors: Too high a dose, too low a dose, or an unknown dose that is likely to be lower than the authorized dose

Guiding principles

  • The dose for Imvamune is 0.5 mL given subcutaneously. In case of vaccine shortages, 0.1 mL dose administered intradermally can also be used for the second dose. Note: errors related to intradermal administration will not be the focus of this document as there is no shortage of Imvamune in Canada.
  • Doses that are too high are considered valid.
  • Doses that are too low should be repeated.
    • If the subcutaneous dose is known and can be repeated on the same clinic day, the remainder of the dose can be administered on that day.
    • If the dose cannot be repeated on the same clinic day, or is unknown, or was too low and given by a route other than the subcutaneous route, the full dose should be repeated as soon as possible.
  • If repeating the dose on the same clinic day, preferably use a separate anatomical site (for example, opposite limb). If use of an opposite limb is not possible, the repeat dose should be given at least 2.5 cm (1 inch) from the previous dose.
  • If repeating a dose after the original clinic day, any appropriate injection site can be used.

Examples

Too high a dose
  • Doses that are higher than the authorized amount are considered valid.
  • The client should be advised of the potential for local and systemic adverse events.
A dose that is known to be too low (administered subcutaneously)
  • Administer the remainder of the dose immediately on the same clinic day, preferably at a separate anatomic injection site (for example, an opposite limb). If that is not possible, use the same limb but separated by at least 2.5 cm (1 inch) from the previous dose and consider the two portions to be a full dose.
  • If not possible to offer the remaining portion of the dose on the same clinic day, provide a full repeat dose as soon as possible at any appropriate injection site.
  • The client should be advised of the potential for local and systemic adverse events.
An unknown dose that is likely to be lower than the authorized dose (for example, leaked out, equipment failure, client pulled away)
  • Administer a full repeat dose immediately on the same clinic day, preferably at a separate anatomic injection site (for example, on an opposite limb). If that is not possible, use the same limb but separated by at least 2.5 cm (1 inch) from the previous dose.
  • If not possible to repeat the dose on the same clinic day, provide a full repeat dose as soon as possible at any appropriate injection site.
  • The client should be advised of the potential for local and systemic adverse events.
A dose that is too low administered by a route other than the subcutaneous route (for example, less than 0.5 mL intramuscularly or less than 0.1 mL intradermally)
  • Administer a full repeat dose immediately on the same clinic day using an appropriate route, preferably at a separate anatomic injection site (for example, opposite limb). If that is not possible, use the same limb but separated by at least 2.5 cm (1 inch) from the previous dose.
  • If not possible to repeat the dose on the same clinic day, provide a full repeat dose as soon as possible at any appropriate injection site.
  • The client should be advised of the potential for local and systemic adverse events.

Interval errors

Guiding principles

Although Imvamune is a live-attenuated vaccine, it does not replicate, and for the purposes of spacing between doses, can be considered like non-live vaccines.

Recommended interval: NACI has recommended that the second dose of Imvamune should be given at least 28 days (4 weeks) after the first dose. When there is no vaccine shortage, the second dose should not be delayed beyond 28 days after the first dose if possible, particularly for those who are moderately to severely immunocompromised.

  • Note that people who are immunocompetent and who previously received a live-replicating first or second generation smallpox vaccine (such as those routinely offered prior to the early 1970s) only require one dose of Imvamune. Those who are immunocompromised should receive two doses of Imvamune regardless of previous smallpox vaccination.

Second dose given at less than 28 days after the first dose: NACI has recommended that if the vaccine series has been administered with an interval less than the recommended minimum of 28 days, the second dose should be considered invalid only in moderately to severely immunocompromised recipients and repeated at the recommended interval from the last dose. For a definition of moderately to severely immunocompromised, refer to NACI Rapid Response: Updated interim guidance on Imvamune in the context of ongoing monkeypox outbreaks, Appendix B: Recommended definition of moderately to severely immunocompromised individuals.

Second dose given more than 28 days after the first dose: Both doses would be considered valid. There is no need to restart or add doses to the series if there is an extended interval between doses.

Examples

The second dose is administered at less than 28 days after the first dose in someone who is not moderately to severely immunocompromised
  • Both doses are considered valid and the series is complete.
  • The client should be advised of the potential for local and systemic adverse events.
The second dose is administered at less than 28 days in someone who is moderately to severely immunocompromised

For a definition of moderately to severely immunocompromised see: NACI Rapid Response: Updated interim guidance on Imvamune in the context of ongoing monkeypox outbreaks, Appendix B: Recommended definition of moderately to severely immunocompromised individuals.

  • The second dose is considered invalid.
  • Offer a repeat dose 28 days after the invalid dose.
  • The client should be advised of the potential for local and systemic adverse events.
The second dose is administered at more than 28 days after the first dose
  • Both doses are considered valid and the series is complete.
The second dose is administered to an immunocompetent individual who previously received a live-replicating first or second generation vaccine
  • Although only one dose of Imvamune is recommended, both doses are considered valid and the series is complete.
  • The client should be advised of the potential for local and systemic adverse events.

Co-administration

Guiding principles

NACI recommends that Imvamune should not be delayed due to recent receipt of an mRNA COVID-19 vaccine. If vaccine timing can be planned (for example, prior to employment within a research laboratory), NACI recommends that Imvamune be given at least 4 weeks after or before an mRNA COVID-19 vaccine. The same advice would also be relevant for the Novavax Nuvaxovid vaccine. This is a precaution to help with attribution of adverse events that may result from a particular vaccine.

Refer to NACI Rapid Response: Updated interim guidance on Imvamune in the context of ongoing monkeypox outbreak and the Canadian Immunization Guide (CIG) chapter on smallpox and mpox vaccine.

Imvamune has not been studied with other vaccines, and NACI does not make recommendations regarding the timing of Imvamune and other vaccines (except for mRNA COVID-19 vaccines as noted above). Although Imvamune is a live-attenuated vaccine, it does not replicate, and for the purposes of spacing with other vaccines, Imvamune can be considered like non-live vaccines. Therefore, all doses are considered valid if Imvamune is given at the same time as, or at any time before or after, any other vaccine, including COVID-19 vaccines.

Storage and handling errors

Guiding principles

Storage and handling errors or deviations for vaccines already administered require individual considerations based on the circumstances, in consultation with the manufacturer and local public health officials and based on clinical judgment. Note that this document is not intended to provide advice on products that have not yet been administered. For this information, see the detailed information on storage and handling provided on the following website, including allowable excursions: Imvamune vaccine: Storage temperatures, shelf life, shipment, supportive temperature excursion information.

In addition to information from the manufacturer, other factors to consider in deciding whether a dose requires repeating and when it should be repeated include:

  • How substantial was the deviation? (for example, how long was the product exposed to an inappropriate temperature and what was the temperature deviation? How long after the expiry date was the vaccine used?)
  • Were there any other errors or deviations in the client's previous dose?
  • What are the client's underlying health/disease related risk factors for infection or serious disease or a less than an optimal response to the vaccine (for example, age and immunocompromising conditions)?
  • Has the client had any significant adverse events after the previous dose?

Detailed information on storage and handling, including allowable excursions, is provided on the following website: Imvamune vaccine: Storage temperatures, shelf life, shipment, supportive temperature excursion information. Use following an exposure of any length of time (except for rapid storage change from freezer to refrigerator and preparation of the product for administration) at +20°C is not supported.

In consultation with the manufacturer and local public health officials, if the dose is felt to exceed allowable storage and handling conditions / recommended expiry dates and available information supports that the dose may not be potent or there is no information to support its potency, the dose should be considered invalid and repeated.

  • The repeat dose could be offered as soon as possible or up to 28 days after the invalid dose, based on clinical judgement of the extent of the excursion and ongoing risk of exposure.

When repeating a dose after an invalid dose:

  • If the repeat dose is given on the same clinic day, preferably use a separate anatomical site (for example, opposite limb). If use of an opposite limb is not possible, the repeat dose should be given at least 2.5 cm (1 inch) from the previous dose.
  • If repeating the dose after the original clinic day, any appropriate injection site can be used.
  • The client should be advised of the potential for local and systemic adverse events.

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