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Interchangeability
Canadian Immunization Guide
Seventh Edition - 2006
Canadian Immunization Guide 2006
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Part 1
General Guidelines
Principles of Vaccine
Interchangeability
This chapter provides the health care
provider with an overview of the general principles of vaccine
interchangeability for the currently approved vaccines in
Canada.
The principles of interchangeability are
only applicable to vaccines with the same indication and specified for the same population (i.e., the same age groups). It has
now become routine to have similar vaccines from different
manufacturers approved for use in Canada. Several factors may
necessitate giving different products to the same individual over
time. When faced with vaccine shortages, deferring vaccination is
not desirable: one study demonstrated that 25% of children whose
vaccination had been deferred never returned for the indicated
vaccine.
Factors to consider in determining
potential candidate vaccines for
interchangeability
- The vaccines should be approved with the
same indications, specified for the same population and be
equally acceptable in terms of safety, reactogenicity,
immunogenicity and efficacy.
- A regularly scheduled primary or booster
vaccine should not be deferred because of the lack of
availability of a particular product.
- Any new regimen should be equally
acceptable from a safety, efficacy and scheduling
perspective.
- Even when vaccines are approved for the
same indications, different manufacturers often use different
production methods, antigen concentrations, stabilizers and
preservatives. Each of these could affect the immunogenicity,
safety or efficacy profile of the product.
Interchangeability following
provincial variations in immunization schedules and
products
- At present, the immunization schedules
as well as the specific products used may vary across the
provinces and territories.
- With immigration and migration of people
between provinces and territories, issues of vaccine
interchangeability have arisen with specific concern regarding
measles, mumps, rubella (MMR), varicella and meningococcal
conjugate vaccines.
- For DTaP-IPV-Hib, the primary
immunization series of three doses given in infancy should,
whenever possible, be completed with a single combination
product. However, on the basis of expert opinion, if
the original vaccine is not known or not
available, it is recommended that an alternative combination
product be used to complete the primary immunization series.
According to expert opinion and the limited data available to
date, NACI recommends that the DTaP-IPV-Hib and DTaP IPV combination vaccine products
currently approved for sale in Canada may be used interchangeably
for the 18 month and 4-6 year booster, respectively.
- On the basis of expert opinion, the MMR
products currently available in Canada may be used interchangeably if
required.
- On the basis of expert opinion, the
varicella products currently available in Canada may be used
interchangeably if required
Development of evidence for
interchangeability
Ideally, as new combination vaccines
become available, there should be randomized controlled clinical
trials evaluating their interchangeability with existing
products. This has only been done in limited instances to
date. Most of our knowledge regarding
interchangeability has been gathered as a result of situations of
vaccine shortages, immigration to areas where different vaccine
products are available, and new product purchases with the
negotiation of new contracts. Given the importance of this issue
and the limited data available regarding the interchangeability
of early childhood vaccines, every opportunity should be taken to
encourage further research in this area.
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