Health and Social Services
H1N1: Dr. Hanley's advice to Yukoners - Part 2
Part 2: What You Always Wanted To Know About The H1N1 Vaccine – And Then Some.
The H1N1 vaccine contains an adjuvant and a preservative. Some people worry that these ingredients are harmful and cause illness or disability in people who are immunized. I’d like to address these concerns here.
An adjuvant is an immune booster. The adjuvant in the H1N1 vaccine contains squalene, vitamin E oil, and polysorbate 80. Squalene is found in many plants and animals, including humans. The squalene in the H1N1 vaccine is extracted from shark liver oil. Polysorbate 80 is a preservative found in some processed foods.
When added to vaccines, the adjuvant boosts the body’s response to the inactivated virus. First, it allows us to exceed 90 per cent effectiveness. Second, we can use less vaccine per person because the adjuvant triggers a much stronger immune response. Adjuvants help us “stretch” the available vaccine so that many more people can be immunized.
What do we know about the safety of this adjuvant?
There is good reason to conclude that the adjuvant is a safe product:
- Many people around the world have been immunized with adjuvanted H1H1 vaccine with very low rates of serious adverse effects.
- A very similar adjuvant has been added to European flu vaccines since 1997; over 40 million doses have been delivered with very low rates of serious adverse effects.
- A mock vaccine containing the adjuvant found in the H1N1 vaccine was administered to 9000 volunteers. Again, no significant adverse effects were found during the first six months following administration.
Taken together, these studies support the conclusion that that adjuvant has a good safety track record.
If the adjuvanted H1N1 vaccine is safe, why do health officials recommend non-adjuvanted vaccine for pregnant women?
There is no evidence that that adjuvanted version is unsafe for pregnant women or children under the age of three years. However, the clinical trials which tested the safety of the adjuvanted H1N1 vaccine did not include either of these groups. So, in an abundance of caution, many public health officials recommended that non-adjuvanted vaccine be offered to pregnant women.
Since then, the World Health Organization (WHO) has strongly endorsed the use of either adjuvanted or non-adjuvanted vaccine for pregnant women. For children under three, the Public Health Agency of Canada (PHAC) and WHO have strongly recommended the use of adjuvanted vaccine, because the non-adjuvanted product produces a much poorer immune response.
It may interest you to know that only the adjuvanted form of the vaccine is used widely in Europe, and there is no evidence of any significant adverse effects among pregnant women or young children in these countries.
What about Thimerosol? Doesn’t this mean that the vaccine contains mercury?
Yes, the vaccine does contain mercury. Thimerosol is a mercury-based substance that prevents growth of bacteria and fungi in the vaccine, and acts as a preservative to ensure long-term stability of the vaccine. In general, we should pay attention to how much mercury we take in. However, the amount of mercury in the vaccine is tiny, and unlike the mercury that is found in fish, comes in a form (known as ethylmercury) that is rapidly eliminated from the body. The type of mercury found in the vaccine has not been found to cause any illness or disability. Furthermore, I am satisfied that several studies have now been carried out which fail to show any link between thimerosol-containing vaccines and autism.
Antibiotics in non-adjuvanted vaccine?
Australia sent Canada non-adjuvanted vaccine to bridge the gap until Canadian production of the non-adjuvanted vaccine was ready. Yukon received 400 doses of the Australian vaccine. Unlike the product in Canada, Australia’s vaccine contains small amounts of antibiotic to reduce the likelihood of bacterial contamination. Because of this difference in vaccine make up, all pregnant women receiving the Australian non-adjuvanted vaccine were screened for allergies to antibiotics.
Adjuvanted or non-adjuvanted vaccine?
Both adjuvanted and non-adjuvanted vaccines are safe, but taking into account all the considerations and with a dose of precaution, my recommendations to Yukoners are:
- All Yukoners aged six months and older should be immunized, unless specifically advised not to by your physician. A pre-existing serious allergic reaction to eggs, or to influenza vaccine would also make it inadvisable for you, at least until you have received instructions and advice from your physician.
- Women who are over 20 weeks along in their pregnancy can and have taken the adjuvanted vaccine. However, now that the non-adjuvanted product is available, the Public Health Agency of Canada does recommend this vaccine as the preferred option.
- Women who are less than 20 weeks and are healthy should receive the non-adjuvanted vaccine. However women in early pregnancy may have been advised to take the adjuvanted vaccine before the unadjuvanted vaccine arrived. We felt very confident with this advice, due to high influenza activity in our community.
- Children under three years of age should receive the adjuvanted vaccine. Young children are at higher risk for complications from H1N1 influenza, and will benefit from the boost the adjuvant gives to the immune system. However, parents can still opt for the non-adjuvanted product if they wish.
As of this date, we have vaccinated over 50 percent of Yukon’s population. As good as that is, our goal must be to vaccinate a large majority of Yukoners. This will protect the greatest number of people from influenza illness. But equally important, we can stop H1N1 in its tracks. When a majority of a population is immunized, the virus can no longer invade, infect, reproduce and spread to others. There is no shortage of vaccine in Yukon and we will continue to vaccinate until all Yukoners who want to be immunized are immunized.
Brendan E. Hanley MD CCFP(EM) MPH
Yukon Medical Officer of Health
