No subject is as polarizing right now than the subject of vaccines. However there is no doubt or debate within the scientific community: vaccines work. The World Health Organization has declared vaccine hesitancy as one of the 10 biggest threats to global health in 2019. But where does this hesitancy come from and how do vaccines really work?
Vaccines are one of the biggest success stories of modern medicine. However a growing group of skeptics has been spreading doubts about their efficiency. The WHO estimates that vaccines save 2-3 million lives a year. But the success of vaccinations cannot always be measured in numbers: in the last 2 centuries vaccines have abolished many devastating infections such as smallpox and among other effects, they have significantly decreased childhood mortality.
A brief excursion into history – vaccinations have been around for centuries
The concept of immunizing yourself against infection has been around for a long time. For centuries people in China and the Middle East have used the principle of “variolation” : live infectious agents, in this case viruses, are taken from the pocks of a person, that had survived the infection. These pathogens are then introduced subcutaneously into a healthy individual, which should help that individual develop an immunity against that virus. This method worked, but it had it’s risks as people were working with live viruses. 2-3% of these people developed a full smallpox infection and some of them died.
In the 18th century a doctor, Edward Jenner, observed that milk maids, who had been infected with the relatively harmless cow pox, were immune to the more dangerous smallpox. He developed the first “vaccination”, from the Latin word “vacca” which means cow. He performed a risky experiment among others on his own son and the son of his gardener to prove his hypothesis. He infected a bunch of children with cow pox and few weeks later exposed them to smallpox. They didn’t develop an infection, which brought him the proof he needed. The era of vaccinations had begun.
How do vaccines work? They use endogenous mechanisms!
Our body has mechanisms that protect it against foreign, sometimes dangerous, compounds or microorganisms – the immune system. Our immune system can differentiate between what belongs to us, and what is foreign. If our body is exposed to a foreign (dangerous) substance, then it will trigger a full immune reaction to defend itself.
A vaccine carries dead, weakened or just parts of a pathogen and still manages to trigger a full immune response – a practice run for when the body encounters the real deal. The body can remember this contact and when it meets this (dangerous) pathogen again, it will be able to defend itself much quicker. The argument that the anti-vaxx movement uses to avoid vaccines to strengthen the immune system is wildly inaccurate. Actually the contrary is true: if you develop and survive a measles infection, your immune system is so weakened that the risk of dying of another infection is quite high.
Also the argument that some combined vaccinations are too much for a child’s immune system is also not true: we are exposed to hundreds and thousands of foreign substances every day and the body develops a immune reaction to all these substances. Adding 2 or 3 from a vaccination won’t really make a difference.
(Useful information: If the body cannot properly differentiate between what belongs to itself and what is foreign, it can happen that it attacks itself. This is the case with autoimmune disease such as multiple sclerosis or celiac disease. )
„If others are vaccinated, then why do I need to?“ – What is herd immunity?
If a high percentage of a population is vaccinated, then a specific illness cannot spread. This phenomenon is called “herd immunity” and it protects vulnerable members of this population such as newborns, the elderly or people with a compromised immune system. If the percentage of vaccinated people drops under a certain threshold, then the infection can spread throughout the population. A good example for failing herd immunity is the spread of measles, an illness that was almost completely eradicated by a successful vaccination program. The principle of herd immunity is only important for infections that can spread from person to person. With infections like Tetanus for example, the only person that carries the consequences of an infection is the person that isn’t vaccinated.
Different illnesses require have a different threshold to ensure herd immunity: with measles this threshold is 95%. 95% of the population need to be vaccinated to ensure herd immunity. With other infections such as diphtheria , this threshold lies by 85%.
Fake News: MMR vaccine and it’s link to autism
One of the biggest hoaxes in modern science with literally fatal consequences is the publication of the article by Andrew Wakefield, that links the vaccine against mumps, measles and rubella ( the so called MMR vaccine) with the development of autism. Financial incentives had driven him to publish a made up study, to help the parents of an autistic child sue the company that produced the vaccine. The article was completely discredited and retracted.
And although this disinformation was made public and the doctor lost his license to practice, the rates of vaccinations dropped, especially in the United Kingdom. Initially, an intact herd immunity managed to buffer the dropping rates of vaccinations, which falsely led to the opinion that vaccinations are not necessary. Nowadays we are strongly suffering from the consequences of an insufficient rate of vaccination. Washington recently declared a public emergency fearing a large outbreak of the measles. The initial outbreak happened in a population, that largely refuses to vaccinate their kids based on their lifestyle choices.
What about side effects?
Every vaccine can have side effects. However they are very rare and shouldn’t overshadow the huge positive effects of vaccines. Most of the side effects are harmless, such as a little reddened skin at the injection site or a slight fever and fatigue. The body needs a lot of energy to produce a full immune reaction. The risk of side effects is always preferable to the devastating and often fatal consequences of a full infection. Also it needs to be considered, that side effects triggered by vaccinations are often milder forms of the severe symptoms caused by the infection.
Anti-vaxxers often use the argument that the side effects are worse than the infection itself – they are not! The historic aspect is often neglected: our generations have not witnessed the suffering some infections led to (Polio, Smallpox, Pertussis etc…) and how the emergence of effective vaccines changed the world by eradicating these illnesses. The perception that people have nowadays that these infections “are not that bad” can also be partially explained by a populations herd immunity.
Where do we go from here?
The decision to vaccinate shouldn’t be a personal one, but should be considered with an altruistic eye. To endanger herd immunity is to expose the weakest members of society, that can not be vaccinated. In addition to this, we live in a era where antibiotic resistance is a sever problem and vaccinations protect us at 2 fronts. Firstly they block the spread of dangerous infections and they reduce the use of antibiotic medications, which promote the development of antibiotic resistant pathogens.
The decision by the anti-vaxxing movement to not vaccinate themselves or their children is no starting to threaten global health, as herd immunity is not given anymore. They use arguments such as a link with autism, a weakening of the immune system and sever side effects to convince others – however this just shows a big gap in knowledge on how vaccines actually work. It is a fact, that vaccines protect us and the people around us. That’s why the choice to vaccinate shouldn’t be a personal one, but vaccines should be compulsory.
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- Alana Colleen. (2015). „Die stille Macht der Mikroben“. München: Rieman Verlag, ISBN 978-3-641-15272-7
- Abbas, A. K., Lichtman A. H., Pober, J. S. (2000). „Cellular and molecular Immunology“. W.B. Saunders Company, ISBN 0-7216-8233-2
- Herd immunity threshold for selected diseases 2013
- Kung, J. “Vaccines and public health”. Presentation
- Jonson, S. “Anti-vaccine movement is powered by ‘hysteresis’, study reveals”
- CDC Vaccines
- Deer, B. (2004). “Revealed: MMR research scandal” , The Sunday Times
- Briseño, C. (2010). „Das offizielle Ende eines Forschungskandals“. Der Spiegel
- Szabo, L. “Study finds vaccine side effects extremely rare”, USA Today
- Wikipedia (Vacciniavirus, Pocken, Variolation, Edward Jenner)
- “Comparisons of the effects of diseases and the side effects of vaccines” Govornment of Western Australia, Department of Health
- WHO “Vaccination greatly reduces disease, disability, death and inequity worldwide”
- Redl, B. (2019). „Daten & Fakten: Was sie über Masern wissen müssen“. Der Standard