Vaccination (Part 1): The Basics

Of the US population, it is estimated that :

  • 70% are pro-vaccination
  • 2% are anti-vaxxer
  • 28% are unsure

This post is not a battle cry against anti-vaxxers (that will come in part 2), but rather, a comprehensive review of the science behind vaccination. The aim is to help anyone who is unsure gain a better understanding of the facts and evidence supporting vaccination.

Hopefully what they find here, will improve their confidence and understanding of vaccination.

When did Vaccination Begin?

Jenner’s work “saved more lives than the work of any other human”

In 1796, smallpox was killing approximately 10-20% of the population. A man called Edward Jenner was about to make one of the greatest medical breakthroughs of all time. He noticed that milkmaids who suffered from cowpox (a non-fatal disease) never caught smallpox. Perhaps the element that protected the milkmaids from smallpox was contained within the pus from their cowpox blisters?

That’s exactly what Jenner thought, and as a test, he used this pus to inoculate his gardeners’ son. When exposed to smallpox material, the boy did not get sick. Jenner successfully immunized his own son (must have been a very persuasive man), and 23 other individuals.

The use of vaccination based on Jenner’s discovery spread like wildfire.

What are the basics of Vaccination?

“Fool me once, shame on you. Fool me twice, shame on my immune system” – Miscellaneous Virologist, Circa 2018.

One thing you need to know about your immune system, is that it learns from experience.

The first time you encounter a particular virus, you will suffer the associated disease, whatever it may be. However, the good news is that your immune system will have learnt to recognise that virus. The next time you meet this virus, your immune response will be better, faster, and stronger than before (thanks Daft Punk). You will be protected from the disease.

The immune response to the first infection (or vaccination) is slow and weak. A much faster and greater immune response is activated when you encounter the virus again.

Today, we simply prime your immune system with a vaccine against a particular virus. Therefore your immune system will be prepared for the first encounter!

What is in a Vaccine?

The main component of a vaccine, is the virus. This may either a component or the whole virus. However, the virus will have been altered in the lab in order to:

  • Reduce or eliminate virulence (ability to cause disease)
  • Maintain immunogenicity (ability to stimulate a protective immune response)

How are Vaccines Tested?

There’s a lot of misinformation out there about vaccine trials, rumours suggest that they are flawed or rushed. Below is an illustration of the standard procedure for such trials:


Notice that safety is monitored throughout all phases of the clinical trials. The trial populations increase with each phase, until they are large enough for rare adverse effects to be picked up (Phase IV).

What happens if rare adverse effects are detected?

e.g. RotaShield

A vaccine against Rotavirus licensed in 1998 was withdrawn a year later due to a rare adverse effect known as intussusception (a rare type of bowel obstruction). This was detected by the Vaccine Adverse Effect Reporting System (VAERS).

Its comforting to know that once a vaccine is licenced for the general population, there are still experts watching over us. They will review any problems reported by families and medical professionals, and they are ready to withdraw a vaccine if a serious adverse effect is discovered.

How do we know Vaccines Work?

Almost every time a vaccine is introduced, there is a compelling drop in the incidence of the disease within a year. The most amazing piece of evidence is  the eradication of smallpox in 1980. It is believed this was achieved mainly due to vaccination.

Measles Graph
Following the introduction of a vaccine in 1963, Measles cases dropped dramatically within a year

Why is coverage important?

Due to legitimate medical conditions, some people cannot be vaccinated (these are known as “Contraindications”). These people are the most “at risk” when an outbreak occurs.

However, if most of the population are vaccinated, the virus will struggle to spread to those “at risk” groups. This is know as Herd Immunity.


If the level of vaccine coverage drops below the level required for herd immunity, outbreaks are much more likely to occur, as can be seen below.

Pertussis Graph
Notice the two drops in % vaccine uptake around 1975 which are followed by two major whooping cough epidemics in 1977-79 & 1981-83


Final Thoughts

Vaccines are without a doubt, one of the greatest medical discoveries of all time. There’s no telling how many lives have been saved by them. Misinformation and complacency will undoubtedly lead to epidemics, unless we get serious about protecting ourselves.

We need to start seeing vaccination for what it really is. Not simply a personal choice, or a  means of protecting ourselves from disease. Vaccination is a duty to your community, because there are people out there who can only be protected by herd immunity.


“Having children is the greatest gift anyone’s ever given me, and if I can help protect anyone else’s gift, then it’s not just my pleasure, but it’s my responsibility to do it.” – Sarah Michelle Gellar, discussing vaccination.











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