PUBLIC HEALTH REPORTER
Public-health officials are preparing to roll out the largest vaccination campaign in Canadian history in the coming weeks, but the public remains confused about the threat posed by H1N1 influenza and the benefits and risks of the vaccine. The Globe and Mail’s Public Health Reporter, André Picard, tries to clear up the “conflusion” by answering reader questions.
I keep reading about an “epidemic” and a “pandemic,” which implies there is an imminent threat. But I just don’t see an epidemic or pandemic out there, just a lot of fear-mongering.
Epidemic and pandemic are technical terms that refer to the geographical spread of a disease, not its severity. H1N1 is a pandemic because it has spread to virtually every country in the world since it first surfaced in humans in March. I’ve had the flu before. What’s the big deal?
The “flu” has become a catch-all term but it is not a cold, or a gastrointestinal bug. Influenza (H1N1 or otherwise) is unpleasant and will put you out of commission for about a week: You suffer fever, coughing, chills, muscle aches and extreme fatigue; many people have trouble getting out of bed. The vast majority of those infected will get better with rest and plenty of fluids but, in some cases, the symptoms can be so severe that they can result in hospitalization and death.
What kind of vaccine is there for H1N1?
In Canada, there are actually two versions of H1N1 vaccine: an adjuvanted vaccine that has the brand name Arepanrix and a vaccine without adjuvants. The Public Health Agency of Canada has ordered 50.4 million doses – enough for two doses for 75 per cent of the population. Inoculation campaigns will begin around the first week of November.
What’s an adjuvant?
An adjuvant is a substance used to bolster the antigens in the vaccine – an adjuvant was used in the H1N1 vaccine because of fears that manufacturers would not be able to harvest sufficient stocks from eggs to make antigen. The adjuvanted vaccine, Arepanrix, contains 3.75 micrograms of antigen; the non-adjuvanted version has 15 micrograms of antigen.
What’s in the adjuvant?
Arepanrix, the product from GlaxoSmithKline, Canada’s sole provider of H1N1 vaccine, uses an adjuvant called AS03, which consists of squalene (shark liver oil), DL-alpha-tocopherol and polysorbate 80. There are claims that squalene, part of the adjuvant used in the anthrax vaccine, was to blame for Gulf War syndrome, but the evidence is weak.
This is a new, experimental vaccine. Has it been properly tested?
The H1N1 vaccine is not experimental. It is the same as past flu vaccines – except with a different antigen, of course – which have a good safety record. New versions of the flu vaccine do not require new human trials each year. The controversial aspect of Arepanrix is the adjuvant. While adjuvants have been used in vaccines for some time, AS03 has undergone limited safety testing. Health Canada insists that there have been no shortcuts taken in the approval process for the vaccine.
Is H1N1 vaccine safe?
Like every drug, the H1N1
vaccine has benefits and risks. The benefit is that it can prevent infection with swine flu – though the protection is not 100 per cent. The risks, for most people, are minimal, and include some redness and maybe a slight fever. But in rare cases, there can be serious complications such as Guillain-Barré syndrome. But those risks are not unique to this vaccine. Isn’t there mercury in the vaccine?
Flu vaccine is packaged in vials that contain multiple doses; to avoid contamination, a mercury-based preservative called thimerosal is added. One dose of vaccine contains about 25 micrograms of mercury, slightly less than what you will ingest in a tuna sandwich. There are persistent claims that mercury in vaccines causes autism but this has been debunked.
Should children get the H1N1 vaccine?
The vaccine is recommended for all Canadians over the age of six months, with few exceptions. However, it is recommended that children under the age of 10 get the vaccine in two doses instead of one. That is because children do not produce as strong an immune response to the antigen as adults do.
Should pregnant women get the H1N1 vaccine?
Pregnant women, whose immune system is suppressed, are at highest risk of complications from the flu. Therefore, it is recommended that they be the first in line to get the H1N1 vaccine. However, it should be noted that the H1N1 vaccine that will be administered to pregnant women, which is packaged in single doses, contains neither thimerosal nor adjuvants.
Should I get the vaccine if I’ve already had the flu?
If you had a laboratory-confirmed case of H1N1, there is no need to be vaccinated. However, bear in mind that only about one-third of people who say they have had the flu actually had influenza.
If I get the vaccine can I still get the flu?
Influenza vaccines are not 100-per-cent effective so, yes, it is possible. However, chances are the symptoms will be more mild. Getting the H1N1 vaccine does not mean you will not get sick this winter; there are other strains of flu and numerous other viruses and bacteria that circulate.
How long can an infected person spread this virus to others?
People infected with the flu shed virus, and they can infect others from one day before getting sick and up to seven days after.
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