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Vaccines - How Do They Work, and Why Are They Important?

October 17, 2017

We all hate getting needles, right? How many times have we come home from the doctor’s, or from school, refusing to move our arm for fear of soreness? So why is it that our parents and teachers insist on them?


Vaccines are incredibly important to not only our own health, but also the health of the community. Thanks to vaccines, we have been able to eradicate smallpox, effectively eradicate polio (only 37 cases worldwide were reported in 2016) and severely reduce many other diseases which have caused many deaths in the past.

In 1796, Edward Jenner made a breakthrough. He introduced matter from a cowpox sore (a disease which humans could get from cows) to an eight-year-old boy, James Phipps. Phipps only had a small reaction, and recovered fully after a couple of days. A month later, Jenner did the same thing to Phipps, only with matter from a smallpox sore, to test whether the previous cowpox infection would protect Phipps from the smallpox. Phipps remained healthy, and the first vaccine was born.



Vaccines are a clever invention. When you are vaccinated, you are injected with a weakened and much safer form of the virus or disease itself, or something very similar. This mimics the disease without putting you in danger. Your immune system reacts, and the lymph nodes inside your body learn how to fight the disease. The weakened disease cells are quickly eliminated, and now your body has been immunised; your immune system knows how to fight that disease.


Not everyone can be vaccinated. People on certain medications or people with compromised immune systems, such as infants and the elderly, can be at increased risk if vaccinated. As such, a critical component of community health is ensuring that every capable person is vaccinated. The more people that are vaccinated, the higher the ‘herd immunity’. As the opportunity for outbreaks of the disease is reduced when herd immunity is high, the chances of infecting an immunocompromised person is minimised. Alternatively, when herd immunity is low, outbreaks of the disease occur (Fig.1). This can be seen in recent events, where several severe outbreaks of measles around the world have been linked to very poor vaccination rates, and as such, very low herd immunity.


Clearly, beyond the personal benefits, getting vaccinated contributes to herd immunity and helps protect those who are at risk. So even though a jab in the arm may hurt at the time, getting vaccinations will save you from potentially life-threatening diseases in the future – and may well save someone else’s life too.











1. Hall V, Banerjee E, Kenyon C, et al. Measles Outbreak — Minnesota April–May 2017. MMWR Morb Mortal Wkly Rep 2017;66:713–717. DOI: http://dx.doi.org/10.15585/mmwr.mm6627a1

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