“Mind your own business and vaccinate your own child. So what if I choose not to vaccinate mine. It doesn’t concern you” says a vaccine-refuser.
His child, his decision and it does not concern anyone else – or so he thought! Before looking at the reason why his decision is a matter of concern to all, let’s take a look at what vaccines really are.
What are vaccines and why are they important?
Vaccines are made from weakened or killed microbes (i.e. bacteria or viruses), microbial toxins which are processed to be less harmful, or microbial surface proteins. They are used to stimulate our own immune system to not only recognize and destroy the microbes which enter the body, but also to ‘remember’ them. This ‘memory’ that is retained by the immune system confers protection against infection by the same microbe in the future.
Vaccination is a cost-effective tool for controlling infectious diseases and is estimated to avert approximately 2 to 3 million deaths annually (World Health Organization). It also helps to limit the use of antimicrobials (such as antibiotics) through disease prevention hence slowing the spread of antimicrobial resistance.
Here’s why abstaining from vaccination harms not only the unvaccinated individual but the people around as well.
Of equal importance is the herd immunity (also known as community immunity) which can be achieved when high enough portion of the community is vaccinated against a specific disease. Herd immunity is important to protect vulnerable individuals who do not mount enough immunity despite being vaccinated or those who may not be suitable to receive certain types of vaccines, such as those who are immune-compromised, pregnant women, infants and those who are acutely ill.
As a case in point, imagine your whole neighbourhood except yourself has been vaccinated against tuberculosis. If all your neighbours are immune to tuberculosis, you are less likely to catch the infectious disease because no one in your neighbourhood will spread this disease to you (unless you catch it from someone outside of this neighbourhood). This is illustrated by the following figure:
It is not difficult to imagine how this specific herd immunity may be compromised if a significant number of individuals are not vaccinated. This explains the danger of anti-vaccine movements (fuelled by fraudulent research) where vaccine denialists are posing health risk not only to themselves but to the vulnerable groups of individuals around them (those who cannot be vaccinated for various reasons), as illustrated below:
The principle of herd immunity based on high enough rate of vaccination within a community has been shown to play a crucial role in controlling a variety of contagious diseases including influenza, measles, mumps, rotavirus (MMR) and pneumococcal disease. Therefore, it is advisable for everyone who is eligible for vaccination to be vaccinated. This is important not only for disease prevention among those who are vaccinated but also for the purpose of herd immunity which can protect all vulnerable individuals from a particular disease.
So if you think your decision affects only yourself, think again!