It used to be that infectious disease was one of the leading causes of death for Canadians, but today it causes less than 5% of deaths annually [1]. The introduction of vaccines has played a significant part in this reduction of deaths, and many of us tend to take this for granted.
The first vaccine, created by Edward Jenner in 1796, was against smallpox. It worked by infecting people with a less serious and related disease, cowpox, which would train their bodies to mount an effective immune response. While intentionally infecting ourselves with a disease sounds a bit scary and counterintuitive, it worked to defend against smallpox because cowpox and smallpox are so biologically similar. Here’s proof: today, smallpox has been completely eradicated, and other serious diseases have also been on decline since the introduction of their vaccines. For example, 5 years before the measles vaccine was introduced in 1963, there were 53,584 cases of measles that occurred annually in Canada [2] with about a rate of two to three deaths per 1,000 people [3]. In contrast, from 2011 to 2015, the average annual number of cases was only 292 [2] and now we tend to spend far less time worrying about it every time our kid gets a runny nose.
However, this trend of declining cases is starting to reverse in many parts of the world and we are being reminded of how lucky we’ve been not to have these diseases at the top of our minds. The increasing rates of these diseases are partly due to a decrease in the rate of vaccination and people not completing a full vaccine course. Vaccination rates for diseases such as diptheria, pertussis, and tetanus remain low with about 70% of children in Canada receiving the recommended vaccine dose [1]. This becomes important as these vaccines not only protect the people receiving them, but also the people who cannot be vaccinated due to allergies or a weakened immune system. This is a phenomenon known as herd-immunity, and it’s powerful. When a population has a high percentage of people immune to an infection, then outbreaks of said infection will peter out due to the chain of infection being blocked. In comparison, when no one or very few people are immune to a disease, an outbreak will spread very quickly from person to person. That means that when we choose to get vaccinated (or not…), we are not only making a choice about our own health, but about the health of those living and working in our communities.
Potentially the most concerning reason for changes in vaccination rates is the “anti-vaxxer” movement sparked by the fraudulent scientific paper published in 1998 in The Lancet by Andrew Wakefield. The paper linked the measles, mumps, and rubella (MMR) vaccine to the development of autism in children. This paper has since been retracted due to Wakefield’s manipulation of data and undeclared conflicts of interest, but the retraction came too late – the paper had already sparked fear and caused the threat of the re-emergence of serious pandemics.
Vaccines do not cause autism, but they can have some side effects. The occurrence of adverse effects depends on the vaccine, but the most common are minor: tenderness at the injection site (as with 75% of children receiving the combined tetanus, diptheria and pertussis [DTaP] vaccine) or a moderate fever (as with 4% of adolescents receiving the DTaP vaccine) [4]. Severe side-effects, such as an allergic reaction, are extremely rare; fewer than 1 out of a million doses of DtaP result in a severe allergic reaction[4].
Some of the other worries over vaccines stem from fears about their ingredients, such as mercury and formaldehyde. It is true that these substances are toxic, but they are not toxic at the trace amount found in vaccines. People more often come in to contact with these substances in their everyday life. For example, mercury can be found in seafood and formaldehyde can be found in car exhaust and cosmetics [5].
Another major concern people have is getting sick from the vaccine itself. If you are receiving an inactivated vaccine (made from dead bacteria or virus) or a subunit vaccine (made from just a small part of the bacterium or virus), it is not possible to become sick because either the virus or bacteria has already been killed or you are receiving only a fragment and not the entire infective agent. As for live vaccines, or vaccines created from severely weakened viruses and bacteria, a minority of people do experience a mild form of infection, but this means that your body is fighting off the infection and training itself to defend you from future infections.
Luckily for us, modern society has shielded most of us from witnessing the horrors of these debilitating and deadly diseases once faced by the population. Previous generations weren’t so lucky. As such, our fear of dying from preventable illnesses has decreased, but the drop in cases does not mean we should be resting on our laurels. The reason for our relative safety from infectious diseases today is because of successful implementation of vaccination programs in the past, so do your part and get vaccinated. It not only protects you, but it keeps the whole population protected, especially the most vulnerable amongst us.
[3] https://www.canada.ca/en/public-health/services/diseases/measles/health-professionals-measles.html
[4] https://www.cdc.gov/vaccines/vac-gen/side-effects.htm
[5] https://www.cdc.gov/vaccines/parents/tools/parents-guide/parents-guide-part4.html
Looking for evidence that vaccines do not casue autism? Here is it: http://www.immunize.org/catg.d/p4026.pdf
Whitney Weigel is a postdoctoral fellow at the University of Ottawa studying the role of the bacteria and viruses in the development of inflammatory bowel disease. She previously completed a two year postdoctoral fellowship at the Helmholtz Institute for Infection Research in Braunschweig, Germany, studying the bacteria Yersinia pseudotuberculosis. She received her Ph. D. and M. Sc. at the University of Louisville in her hometown Louisville, Kentucky, USA where she worked on bacteria involved in periodontal disease.
