In February 2009, Infanrix-hexa will be introduced in BC. It is a combination vaccine for infants starting their primary vaccine series against diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type B, and hepatitis B. The primary advantage of Infanrix-hexa is a single injection against all six diseases including hepatitis B. This vaccine is to be used for the doses given to infants at 2, 4, and 6 months of age, and will replace the use of Pediacel and Recombivax HB (hepatitis B) at these ages. The booster dose at 18 months will continue to be given with Pediacel. Infanrix-hexa and Pediacel are not deemed interchangeable for the primary three-dose infant series, which should be completed with the same product used for the first dose.
Providers will have become accustomed to a fully liquid product for the DPT-IPV/Hib series with Pediacel. Infanrix-hexa, like Pediacel’s precursor Pentacel, requires reconstitution of the lyophilized Hib, which is contained in a separate vial, using the liquid DPT-IPV-hepatitis B vaccine, which is supplied in a pre-filled syringe. Administration involves the following steps: shake the syringe to obtain a homogenous turbid white suspension, inject the full contents of the syringe (containing the liquid vaccine) into the vial containing the lyophilized Hib vaccine, and shake the resulting mixture to fully dissolve the Hib component. The resulting “hexa” product is administered intramuscularly, in the anterolateral thigh of the infant, using a 7/8" to 1" needle. Infanrix-hexa may be administered at the same visit as Prevnar and Neisvac-C but at a different injection site.
Infanrix-hexa contains higher content than Pediacel of diphtheria and tetanus, equivalent polio types 1, 2, and 3, and higher pertussis antigenic content for the three components that are present in both vaccines (pertussis toxoid, filamentous hemagglutinin, and pertactin). Infanrix-hexa does not contain pertussis fimbriae agglutinogens 2 and 3, and is considered a three-component acellular pertussis vaccine unlike that in Pediacel, which contains a five-component pertussis vaccine. Efficacy against culture confirmed pertussis with at least 21 days of paroxysmal cough is similar between the two vaccines, although the five-component vaccine may have greater efficacy against mild pertussis. There are no head-to-head studies comparing Infanrix-hexa with Pediacel for the primary series. The immunogenicity and reactogenicity data from 22 studies of Infanrix-hexa, Infanrix-IPV-Hib, Pediacel, and Pentacel have been reviewed by the National Advisory Committee on Immunization and deemed to indicate comparable levels of protection. The reactogenicity profile is also similar with respect to the frequency and severity of local and systemic reactions. The immune response to the hepatitis B vaccine component is higher after Infanrix-hexa compared with separate administration of Pentacel and Recombivax-HB vaccines. Similar findings have been seen in studies comparing Engerix-B with Recombivax-HB administered alone.
Infanrix-hexa is a GlaxoSmithKline product and was approved for use in Canada in 2004. It has been approved in many of the European Union countries and has been in routine use in Australia since 2005. The original formulation of the product approved in 2004 in Canada included thimerosal as a preservative in the Engerix-B (hepatitis B) component of the vaccine. BC elected to wait for the approval of the thimerosal-free formulation, now available, because a decision had been made to use thimerosal-free vaccines for infant and childhood immunization when possible. This was based on a desire to maintain public confidence in vaccines because of ongoing concerns about the safety of the mercury-based preservative, despite the demonstrated lack of association with adverse outcomes, including autism spectrum disorders.
BC is the only Canadian jurisdiction introducing Infanrix-hexa at this time. Yukon Territory, Northwest Territories, Newfoundland, New Brunswick, and Prince Edward Island also have infant hepatitis B programs, but at present these are on other three-dose schedules ranging from birth to 15 months of age, whereas the 2-, 4-, and 6-month hepatitis B schedule in BC lends itself to ready Infanrix-hexa adoption.
For complete information on the Infanrix-hexa product and related recommendations, please refer to the references below. Additional materials will be provided to health care providers in BC as this product is introduced.
1. Infanrix-hexa product monograph, GlaxoSmithKline Inc, 2008. www.gsk.ca/english/html/our-products/vaccines-canada.html (accessed 15 Dec 2008).
2. Statement on the recommended use of pentavalent and hexavalent vaccines. Canada Communicable Disease Report, 1 February 2007, Volume 33 (ACS-1): 1–16, and associated literature review by Gilca V, Duval B posted at same site. www.phac-aspc.gc.ca/naci-ccni/index-eng.php (accessed 15 Dec 2008).
3. Provincial and Territorial Immunization Programs, Routine Schedules for Infants and Children, Public Health Agency of Canada, 2007. www.phac-aspc.gc.ca/im/ptimprog-progimpt/index-eng.php (accessed 15 Dec 2008).
Dr Naus is the director of the Immunization Program and associate director of Epidemiology Services at the BC Centre for Disease Control. She is also an assistant professor at the School of Population and Public Health, UBC.
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