Real World Problems: Vaccines

For this week’s topic on Real World Problems, I collaborated with PhD to Success (IG: phd_to_success) to discuss vaccines and their role in public health.

The role of vaccines in public health

A vaccine is something we put in our bodies that looks like or has a tiny part of the ‘microbe’ that produces a disease. When we introduce it in our body, the immune system produces the right antibodies to fight it. The immune system also is quite smart andremembers” this, so that it is able to recognize and destroy any of these microorganisms that show up later on.

The act of introducing an active ingredient to stimulate an immune response is not a new idea. Before the 15th century, primitive forms of inoculation are believed to have been practiced all over the world. For instance, ancient Chinese may have taken small pieces of smallpox scabs and inhaled or rubbed them on their skin to become immune.

image528251xFrom the 1500 to 1900’s, various infectious diseases were very common. Smallpox, measles, whooping cough, chicken pox, and influenza are examples of diseases that were highly contagious. With the discovery of the Americas and movement of European settlers, many native people were introduced to diseases that caused 80 to 95% of them to perish due to lack of immunity. The world’s first “true” vaccine was in 1796 when Dr. Edward Jenner found that he could infect people with a benign cowpox virus, people could be immunized and therefore overall mortality rates due to smallpox could be reduced.

e0a4ffc1a6e6120cb2efb8c6a58dcc93.jpgA common misunderstanding is that diseases had already been disappearing even before the introduction of vaccines due to better hygiene practices. Indeed, better hygiene and sanitation, as well as better nutrition, contributed greatly to the health of populations. You can also say that the development of medical treatments, antibiotics, and less crowding of populations have also contributed to better health. However, when analyzing the correlations of all these factors with a drop in infectious diseases, it is clear that vaccines are most prominent causes of preventing diseases. By looking at vaccines and the incidence of disease (new cases of a disease) over time, the relationship becomes more than just a simple correlation. For example, the permanent drop in measles incidence coincides with the measles vaccine beginning in 1963. Sanitation today is not any better than it was in the 1900s, and therefore cannot be attributed the drop in diseases. This is particularly true for the Hib vaccine as huge drops in the Hibs disease all throughout the world have been attributed to the vaccination.

“But I know someone who has been vaccine injured!”

Let us repeat, vaccines are actually incredibly safe. Let’s talk about common ingredients for vaccines. A vaccine is made of an active ingredient and other added ingredients. The active ingredient triggers the immune response. The added ingredients have different roles, such as improving the immune response, or acting as a preservatives, stabilisers or suspending fluids.

These added ingredients are those contested due to their toxicity. But when speaking about toxicity, there is a very important point to make. An important indicator of toxicity is LD50 (lethal dose 50), which is the dose at which 50% of individuals die. For example, aluminium salts are used in many vaccines as adjuvants. This means that they help by stimulating the immune response and by a slow release of the active ingredient. The most used salts are aluminium hydroxide, aluminium phosphate and potassium aluminium sulphate. Data about these compounds are freely accessible by searching for their material safety data sheets (MSDS) on the big chemical suppliers’ websites, such as Sigma Auldrich. None of the salts above are reported as carcinogenic, and the LD50 of aluminium phosphate, for example, is more than 5,000mg/kg for mice. The total quantity of the aluminium in a vaccine is less than 1mg (0.001g), which is a very low quantity. In the normal European diet the amount of aluminium we intake from food varies between 3–10mg a day.


Vaccine composition lists also include compounds and products used in the manufacturing process – even though at the end of manufacture they are present only in trace amounts, if at all. One of the chemicals on this list that scares people is formaldehyde, which is indeed carcinogenic with an LD50 of 42mg/kg for mice. Nevertheless, the quantity present in a vaccine dose is less 0.1 mg. One 200g pear contains 12mg of formaldehyde. We should always remember ‘the dose makes the poison’.

“Herd immunity is a myth! I know someone who hasn’t been vaccinated, and they’re just fine.”

Some people argue that because many vaccinated people still get the disease, herd immunity is a myth and vaccines are overall ineffective. Vaccines are not 100% effective. Not everyone who receives a measles vaccine becomes immune. However, most routine childhood vaccines are effective to 85-95% of recipients. In countries like the US, those who are vaccinated far outweigh the number of those who are not. Therefore, when outbreaks occur, herd immunity allows for those with more compromised immune systems to be protected from contracting the disease.  Let’s look at this example:

“In a high school of 1,000 students, none has ever had measles. All but five of the students have had two doses of measles vaccine, and so are fully immunized. The entire student body is exposed to measles, and every susceptible student becomes infected. The five unvaccinated students will be infected, of course. But of the 995 who have been vaccinated, we would expect several not to respond to the vaccine. The efficacy rate for two doses of measles vaccine can be as high as >99%. In this class, seven students do not respond, and they, too, become infected. Therefore seven of 12, or about 58%, of the cases occur in students who have been fully vaccinated.”

In other words: The vaccine wasn’t 100% effective for everyone. However, 100% of children who did not get vaccinated got measles. Less than 1% of children who got the vaccine got measles. In the case where no one had been vaccinated, all 1,000 students would end up getting measles. When the majority of the population (83 to 94%) is immunized, a large proportion of the population is immune, therefore contributing to a herd resistance to disease for those who have not developed immunity to a disease.

Vaccines themselves do not solve all of the world’s health problems. However, they provide safety to populations who are at risk of contracting some of the world’s most debilitating infectious diseases. Make healthy choices and do your research!

You can read more about the common misconceptions about vaccines from the WHO or CDC. Always do your own research and read with a critical eye!


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1 Comment

  1. Thanks for this amazing collaboration. I have learned so much about vaccines and their story. Hope this article can reach as many people as possible. #strongertogether.

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