Some H1N1 Vaccine Questions Answered

Despite the massive lineups at H1N1 flu shot clinics across the GTA this week, many people, especially parents, still have questions and concerns about the new pandemic vaccine.

As of Friday morning, 86 per cent of respondents to our two-day, unscientific, online poll question ‘Do you plan to line up for a flu shot this week?’ have answered ‘No’.

The long wait times at immunization centres — intended for those in high-risk groups — may have deterred many GTA residents from getting the shot this week, but lingering questions about the new vaccine may also be contributing to people’s decision to wait, or, possibly forgo.

CityNews.ca posed some questions to the Public Health Agency of Canada, hoping to clarify some points for you about the new vaccine.

Here’s what PHAC representative Nadia Mostafa told us:

Question: Do other vaccines in Canada contain adjuvant?

NM: Adjuvants are not new. They have been used for several decades to boost immune response to vaccines. Many of the commonly used vaccines in Canada contain an adjuvant. However, they have not previously been approved for use with influenza vaccines in Canada.

The adjuvant has been tested in over 45,000 people around the world and has been evaluated by Health Canada as part of the review of the mock H5N1 prototype vaccine during the pre-pandemic period (for more on that, click here). No significant safety concerns regarding use of the adjuvanted vaccine have been raised.

The H1N1 vaccine, both the adjuvanted and non-adjuvanted versions, was tested in clinical trials before it was approved for use in Canada.

A similar adjuvant has been used in a seasonal influenza vaccine products marketed in Europe since 1997. Over 40 million doses have been distributed and there have been no known safety issues.

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Question: What are the ingredients in the adjuvant?

NM: The adjuvanted vaccine includes a booster element that helps the immune system develop a stronger defence against infection. For the H1N1 flu vaccine, the adjuvant is made up of a combination of naturally occurring oil (called squalene), water, and vitamin E.
 
The ingredients are also listed in the “product leaflet” that is available on Fightflu.ca

Click here to read that pamphlet. Click here to read the Authorization of Sale: Arepanrix H1N1.

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Question: Why did Canada approve a vaccine containing adjuvant when the United States did not?

NM: The World Health Organization (WHO) urges the use of dose-sparing formulations that use adjuvant to maximize antigen-sparing, permitting more vaccine to be available.

The WHO recommends an adjuvant-based vaccine. Recent clinical trials performed on a prototype “mock” vaccine have shown that for a novel virus to which people have never been exposed, increased amounts of antigen is needed to provide better protection.

Adding an “adjuvant” to the vaccine allows for a larger amount of vaccine to be produced (dose-sparing) and still be effective. An adjuvant-based vaccine also has the potential to provide better cross-protection against mutating flu virus strains.

Canada is confident in the safety and efficacy of this vaccine. Vaccine safety monitoring will continue to be carried out as the vaccine is used.

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Question: Pregnant women are being offered unadjuvanted vaccine. Why aren’t children over 6 months and under 5 years of age not offered the same vaccine?

NM: All data to date indicates that adjuvanted vaccine is as safe as unadjuvated vaccine.
 
Unadjuvanted vaccine can be considered for children aged six months to three years. However it may result in a poorer immune response in that age group and so adjuvanted vaccine is recommended instead.
 
Children from six months to nine years of age should receive the adjuvanted vaccine in two half-doses, administered at least 21 days apart.
 
A small supply of unadjuvanted vaccine has been ordered for pregnant women. The provinces and territories have agreed that this limited supply of unadjuvanted vaccine should be reserved for this group.

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Question:  Health Canada approved this adjuvanted vaccine with limited Canadian testing. Why?

NM: Health Canada began evaluating the adjuvant component of the H1N1 vaccine in 2007 and has reviewed data from clinical trials with an H5N1 mock vaccine conducted in the United States, Canada and Europe involving 13,000 patients. For the actual H1N1 vaccine, data were analysed from a Belgian study of 130 patients and a German study of 130 patients. At the time of authorization, Health Canada had reviewed safety and/or immunogenicity data involving just over 900 patients. This includes subjects from the two European trials conducted in Belgium and Germany (approx 260 subjects aged 18-60 years), as well as 666 subjects enrolled in three different GlaxoSmithKline trials involving the adjuvanted vaccine (conducted at sites in the US, Canada, France, Germany, and Japan).

The clinical studies are conducted to indicate that the vaccine is safe and that the recommended dose is appropriate to produce an adequate immune response.

GSK’s global clinical development programme includes studies in over 9000 subjects including healthy adults, the elderly and children (including infants) in Europe, Canada and United States. The results from these studies and any other information on vaccine safety and effectiveness will continue to be assessed by Health Canada and the Public Health Agency of Canada. GSK should be contacted directly for specific details on their clinical trials, including information on age groups.  

Health Canada is confident of this vaccine’s health benefits. Health Canada would not authorize a vaccine unless it had evidence that the benefits outweigh any potential risks. North American clinical trials, which began in October, will be used as part of ongoing work to evaluate the vaccine’s safety and effectiveness in larger and more specific population groups. Such post market evaluation of pandemic influenza vaccines is in line with the plans of all other major regulatory agencies.