Vaccine Safety

Frequently Asked Questions

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Do vaccines work?

Yes, vaccines work very well. We know that in countries where vaccination rates are high, disease rates are low. We also know that the opposite is true. In countries where vaccination rates are low, disease rates are high.

Here are some examples:

• In the United Kingdom, in 1974, the number of people who got the vaccine against pertussis (whooping cough) dropped. By 1978, the country had an epidemic of this disease. More than 100,000 people got it, and 36 people died.
• A diphtheria epidemic happened in the former Soviet Union because children stopped getting the vaccine and adults did not get booster shots. The number of cases of this disease soared from 839 in 1989 to nearly 50,000 in 1994. About 1,700 people died.

Thanks to vaccines, there has not been a single case of smallpox in the world since 1977. Polio has been wiped out in North, Central and South America, as well as other countries.

For more details, please see the chapters on specific vaccines in the Canadian Immunization Guide, 7th Edition 2006.  Some vaccines also work by creating “herd immunity”. When most people in a community have received a vaccine for a particular disease, the chance of an outbreak of that disease is greatly reduced. This “herd immunity” protects the small number of people who cannot be immunized for medical reasons or for whom the vaccine did not work.  For herd immunity to be effective, however, as many people as possible must be vaccinated.

Did you know that?

• The World Health Organization (WHO) and similar organizations are convinced that vaccination gives many more benefits than it costs. The WHO estimates that every year, more than two million deaths are prevented worldwide due to immunization.
• The World Bank has stated that countries around the world should FIRST invest in vaccination programs when they are setting up public health programs.

How long do vaccines last?

Your body makes antibodies in two ways: by getting the disease or by getting the vaccine.  Getting the vaccine is a much safer way to make antibodies without having the suffering of the disease itself and the risk of becoming disabled or even dying.

After receiving a vaccine, the antibodies produced by your body stay with you for a long time.  They remember how to fight off the germ.  If the real germ that causes this disease (not the vaccine) enters your body in the future, your defence system knows how to fight it off.

Often, your defence system will remember how to fight a germ for the rest of your life.  Sometimes, your defence system needs a booster shot to remind it how to fight off this germ.    
For diseases, such as diphtheria and tetanus, you must have a booster shot every 10 years to remind your defence system of these diseases and stay protected.

The vaccine for the flu (or influenza) is unusual because people have to get it every year. The viruses that cause influenza are always changing, so new vaccines are needed to prepare your defence system to fight against new germs every year.

Where can I get more information?

• Vaccine Safety Frequently Asked Questions (FAQs)
• Misconceptions about Vaccines and Facts
• Vaccine-Preventable Diseases
• Along with other resources and information, you can read the Canadian Immunization Guide – Seventh Edition (2006).
• Your Child's Best Shot , Canadian Paediatric Society (CPS)
• Canadian Coalition for Immunization Awareness & Promotion

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