The Vancouver Sun by Georgia Perona-Wright and Pauline Johnson 6 May 2014
Measles outbreak and resurgence of polio show importance of immunization
If you could take a shot that would prevent cancer, would you? Would you give it to your child?
Infections can be just as deadly as cancer, and they also spread, passing from person to person through coughs and sneezes, door handles, water supplies and children’s kisses. But, thankfully, shots capable of preventing disease from many infections exist.
However, now falling vaccination rates are allowing measles to return in Canada, and the recent spread of polio into countries such as Syria and Iraq has motivated the World Health Organization to issue a public health emergency. There is a continuing need to maintain high immunization rates to protect ourselves and prevent the spread of disease.
Vaccines work. They stop infections, avoid deaths and reduce suffering. They are one of the biggest medical breakthroughs of the 20th century. The recent outbreaks of measles in the Fraser Valley and Calgary, and now the global resurgence of polio are cruel reminders of how essential childhood vaccinations are.
Measles kills one or two of every 1,000 people infected and polio can cause partial or fatal paralysis. The introduction of the measles vaccine to Canada was a spectacular success, reducing the number of children infected each year from 15,000 to fewer than 15. The polio vaccination program in Canada was so successful that Canada was declared polio-free in 1994.
Concerns about adverse reactions to vaccinations have to be balanced against the risks of the disease itself. The number of parents willing to decline vaccinations for their children is good evidence of how effective those vaccines are: We have forgotten how serious infections can be.
Vaccines work and are remarkably safe. Any vaccine approved for use has undergone up to 10 years of development and testing to ensure it’s safe and effective. Many of the fears surrounding vaccines come from anecdotal reports of very small study groups. These unsubstantiated reports have been widely discredited. The British doctor who made the first, fraudulent claim linking vaccination with autism has been forbidden to practice medicine in the U.K.
Despite this, the anti-vaccination campaign continues to receive considerable public exposure, and so we, as professors in immunology, have been motivated to write this article to help provide a balanced perspective. The scientifically rigorous evidence from study groups containing thousands of people shows vaccines are safe and effective. Rejecting this is putting lives at risk.
Are vaccines perfect? Not yet, and that’s why research continues and essential. It will allow us to improve existing vaccines and develop new ones for diseases we haven’t yet prevented, such as HIV-AIDS.
Vaccines work by improving our natural defence mechanisms against a specific infection. If the immune cells that protect us against infection were soldiers, vaccines double the troop numbers and triple their weaponry. Every time we encounter bacteria or a virus, our immune system not only fights it but also remembers what it is. This immune memory means that the next time we are exposed to that germ, our response is quicker, stronger, and much more effective. Vaccines are designed to generate this immune memory. The vaccine might contain a killed version of the germ or a small piece of the germ that can’t cause infection on its own. It generates immune memory the same way a real infection would, but without the risks of disease.
But vaccines have an additional benefit, too. Not only do they protect individuals, they also stop the spread of the disease within communities. Vaccinating against measles is like pulling up the drawbridge to your castle, refusing to let the virus in. If everybody does the same thing, the virus has no refuge and is condemned to a lonely death outside. In this way, vaccines lower the amount of virus present in the environment and reduce the chances of anyone becoming infected, even vulnerable people — babies, seniors, cancer patients — who can’t protect themselves. This group effect means that vaccination is the single most important health measure your community can take to reduce disease.
The recent outbreak of measles in the Fraser Valley demonstrates that when infection enters a community with a low vaccination rate, disease spreads rapidly. The tipping point at which a virus can gain a foothold in the community depends on the particular microbe: for measles, about 94 per cent of people must be vaccinated to shut the virus out.
The spread of measles through Western Canada and the resurgence of polio should be a call to arms. We can all participate in helping prevent disease: We should vaccinate our children and receive booster shots ourselves. Schools and universities should require vaccination records before admitting students.
Immunize.ca offers a free mobile app to help you keep track of your families’ vaccinations. Use it, and know that you are helping your neighbours, too.
Georgia Perona-Wright and Pauline Johnson are professors in the Department of Microbiology and Immunology at the University of British Columbia.