Vaccine Safety

Frequently Asked Questions

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Can vaccines transmit animal disease to people?

Answer: Because vaccines are a natural product, they sometimes require the use of animal cells during production. This process is strictly controlled so that it does not pose a risk to people. No brain cells are used in manufacturing vaccines in Canada. During the manufacturing process, the vaccines are purified, and all animal cells are removed. However, each batch of vaccine is tested to ensure that it is free from infectious agents.

For some vaccines in Canada, material derived from cows (for example, gelatin and lactose) have been used in the manufacturing process, and this has raised the question of whether vaccines can transmit "mad cow disease" to humans. Scientists in several countries have studied this risk and estimated that, in theory, there could be a risk of one person in 40 billion being exposed to the disease through a vaccine. Even though the risk is extremely small, vaccine manufacturers are working to find alternatives to these components. Meanwhile, Canada is making sure that any vaccine ingredients derived from cows come only from countries that are free from mad cow disease.

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