http://www.carleton.ca/jmc/cnews/n1.shtml

A shot for the flu, with mercury too

By Michelle Catton 

Fluviral®, a brand of flu vaccine offered in Canada this year, contains 25 micrograms of mercury per dose.
OTTAWA  |  Nov.28, 2003 — Canadians are getting a dose of something unexpected with their flu shots this season: mercury. Provincial and territorial governments use an influenza vaccine that contains the mercury compound thimerosal as a preservative. They buy it because it's less expensive than vaccines without mercury.

"There’s been much public concern about thimerosal because it’s mercury containing," says allergist and clinical immunologist Eric Leith.

Mercury content

The free flu vaccine used in Canada contains 25 micrograms of mercury, not enough to be toxic, Leith says. But it's enough to cause allergic reactions in a small number of people.  Twenty-five micrograms in a half-millilitre of vaccine is equivalent to a penny-size blob of mercury floating in an 11-litre jug. 

'There are risks to everything, and this type of flu vaccine is not a panacea.'  Thimerosal kills bacteria or active virus that may contaminate the vaccine. It has been used since the 1930s, but Canadian and U.S. health officials have removed it from most childhood vaccines.

This year, the flu vaccine — despite its thimerosal content — has been recommended for pregnant women and children over six months of age. There has been speculation in the medical community that thimerosal in childhood vaccines may contribute to such disorders as autism, attention deficit hyperactivity disorder and speech or language disabilities.

"There are risks to everything, and this type of flu vaccine is not a panacea," says Gerald Buchanan, an organic chemist. There are flu vaccines that contain less than one microgram of mercury. However, Health Canada writes in its report on thimerosal use that these vaccines are "significantly more expensive and less convenient to use in a large-scale immunization program."

Allergic reactions

As the number of people being vaccinated rises, there is a greater chance for allergic reactions to thimerosal, Leith says. "The more people recommended to take the flu vaccine, the greater chance of reactions." More Canadians than ever are expected to line up for flu shots this season.  A U.S. study found that between one and six per cent of people tested developed a skin rash when thimerosal was directly applied to their skin. However, Leith says, this rarely causes problems during vaccination.

"The general concern is, if someone has sensitivity, are they going to have a local hive reaction or are they going to have a more potential anaphylactic reaction," says Leith. Anaphylactic reactions can cause difficulty breathing, hives, and can even result in death. This reaction is extremely rare, Leith says. "There are probably many people, at this moment, getting the flu vaccine and not having problems." People are asked to sign waivers before they take the vaccine, which sometimes warn people allergic to thimerosal to alert their doctor before getting the shot. Yet many patients don’t know what thimerosal is.

"If you remove additives, you minimize adverse allergic effect," Leith says. Thimerosal is about 50 per cent mercury by weight, Buchanan says. When it enters the body, it breaks down into ethylmercury and thiosalicylic acid, which is similar to aspirin.  "There is some accumulation of ethylmercury (in the body) because it is soluble in fat tissue,” says Buchanan. Doctors think some of the mercury is passed out in the stool.

Widespread vaccination

Ontario is the only province where the vaccine is free to all residents. Most other provinces offer free flu shots for the elderly and people at risk for complications from the flu, such as HIV/AIDS patients and children with cystic fibrosis. A student reads a consent form before getting his shot at a Carleton University flu clinic.   "The whole approach to flu vaccination has been liberalized in the past few years," says Dr. David Pfeiffer, director of Health Services at Carleton University. "Initially, there were select groups, targeted groups, and now there’s a general sense that everyone can benefit."

Clinics in Ontario are provided with the vaccine free of charge, and bill the province $8.50 for each shot they administer. At a one-hour flu clinic, his team of nurses vaccinated more than 70 people, Pfeiffer says. Pfeiffer says the number of people getting vaccinated is expected to rise this year for two reasons: post-SARS concerns, and "increased encouragement from the government to get the shot." Leith and Pfeiffer both say the presence of thimerosal shouldn't discourage people from taking the flu vaccine. Each person should weigh the benefits of receiving the vaccine against the small possibility of an adverse reaction.

"It’s always a matter of risk-benefit ratios," Pfeiffer says.

Are the people at the FDA and CDC and AAP even sane?

Posted by: "andrewhallcutler" AndyCutler@aol.com  

Sat Dec 29, 2007 9:40 pm (PST)

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