Vaccines are one of the greatest gifts bestowed on humanity by the science of medicine. They can be credited with the eradication of several severe diseases that no longer threaten most of the population in all developed countries and in most of the developing world. Terrible diseases such as small pox, polio, diphtheria, tetanus and others are a thing of the past with extremely small infection rates. The methodology behind vaccination relies on the presentation of an attenuated form of the disease perpetrator (pathogen) or parts of it to the immune system in order to generate an immune response that enables the development of immune memory to that pathogen.

In this manner, future encounters with the pathogen can be easily dealt with by the immune system. Despite this, recent years have seen a rising phenomenon of parents who decide to forgo vaccination for their children, for various reasons. In this article I will try to present the arguments used by these parents and anti-vaccination advocates and the responses of the majority of the scientific community. Before doing so I suggest that you watch the following excellent lecture by Seth Berkley, in which he discusses the importance of vaccines and presents innovative technologies for vaccination against pathogens that are hard to vaccinate against, such as the influenza (flu) virus and HIV, the virus behind AIDS.

Seth Berkley's lecture on TED talks.

Dr. Edward Jenner, an Englishman, was the pioneer of the practice of vaccination. In 1796, based on his observation that milkmaids who contracted cowpox were generally protected from smallpox, Jenner extracted pus from the blisters of cowpox-inflicted milkmaids and injected it into a "volunteer" boy, who became immune to small pox. Indeed, Jenner defined this pus as a therapy that can prevent infection with smallpox. It was later learned that the cowpox virus is similarly structured to the smallpox virus. Jenner's new medical practice was at first a subject of mockery by the medical community. Almost a century later, in 1885, the French microbiologist and chemist Louis Pasteur developed an anti-rabies vaccine for which he received much recognition and praise. In fact it was Pasteur who first coined the term vaccine, after vacca, the Latin word for cow, this in honor of Jenner's use of the cowpox pus. Since then vaccines have been responsible for the eradication of many disease and thus the saving of millions of lives, human and animal alike. Lately, however, various groups began advocating "natural solutions" for the prevention of infectious diseases instead of the use of vaccines. A decline in the rate of vaccination led to a rise in the prevalence of several infectious diseases, such as local measles outbreaks in several countries, a 2012 pertussis (whooping cough) outbreak in New York and a 2005 Polio outbreak in Minnesota. A common observation in these outbreaks was that they occurred in non-vaccinated populations. Statistical analyses have shown a reverse correlation between vaccination rate and the prevalence of infectious diseases in the population.

One example of the inverse correlation between vaccination rate and infection rate.

An interesting occurrence about 40 years ago in Europe demonstrates how dramatic and rapid the effect can be. Whooping cough is a childhood disease caused by a bacterium that secretes pertussis toxin, which obstructs intracellular signaling pathways. Symptoms include acute coughing attacks that in severe cases can lead to cerebral hemorrhage, intestinal bleeding, damage to the diaphragm and even death. Vaccination for pertussis was introduced in the 1940s, leading to a dramatic decline in infection rates, but not to complete eradication. In the late 1970s, due to public protest, the vaccination rate against the disease dropped from 80% to about 40% within 5 years. The consequences followed rapidly: in 1977 a whooping cough outbreak saw the infection of 100,000 people, most of them toddlers between ages 2-5. Twenty three lost their lives. While the mortality rate was "only" 1:4000, most deaths were of babies less than 3 months old. One of the more heartbreaking cases was of a one week old baby who became sick and died 4 days later. Similar outbreaks occurred also in Japan and Sweden, where vaccination rates also declined significantly. For further reading on the subject you can refer to an article published in the highly esteemed Lancet medical journal. The message from these events is clear: vaccine avoidance is an irresponsible act that affects the weakest groups in the population. Nevertheless, the web is full of stories of children who contracted whooping cough after their parents chose "the natural way".  

Different groups choose to abstain from vaccination for various reasons, be it fear, ideology or simply lack of awareness. One thing is shared by all these groups: they benefit from "herd immunity", which means that they are very unlikely to be infected if a high enough proportion of their community is vaccinated. Aside from this being an act of selfishness, vaccination avoidance entails a greater problem: since no vaccine is 100% infallible, a person who was vaccinated can contract a disease from a non-vaccinated person, and the more non-vaccinated people there are the greater the chances of this happening. In 2007 two measles-carrying guests from England attended an ultra-orthodox Jewish wedding in Jerusalem. As all the guests belonged to a radical faction that refuses to be vaccinated for ideological reasons, nearly 200 people became infected with measles in their community. This incident persuaded even the most adamant opposers to promptly have their loved-ones vaccinated. If this had been a more dangerous disease, such as polio or diphtheria, the fates of these people would have been much more unfortunate. So why do so many people still refuse to have their kids vaccinated? The following are several of the more common arguments against vaccination and the appropriate scientific rebuttals:

Disease eradication should be attributed to increased hygiene and the discovery of antibiotics, not to vaccines.

Since the discovery of antibiotics there has been a dramatic decline in mortality from infectious diseases. However, if you pay attention to the details you may ask: what about the rate of infection? A clear inverse correlation exists between vaccination and infection with a variety of diseases such as measles, polio, diphtheria, tetanus, pertussis and more. The mortality rate from these diseases has certainly declined, but life-long paralysis (such as in the case of polio) or brain damage (measles) are certainly not something one would aspire for.

Vaccine formulations contain hazardous and toxic materials such as mercury.

Not true. The mercury component (thiomersal) has been removed from all vaccines in recent years. When it was present in vaccines, the amount of mercury was smaller than what you would find in a tuna sandwich, and this together with the fact that mercury exposure by vaccination was limited to a finite number of vaccines in early childhood made it physiologically insignificant. Another ingredient that vaccination avoidance advocates point out is the aluminium salt adjuvant (an immune-stimulating agent that is added to increase vaccine effectiveness). According to the US Food and Drug Administration (FDA), based on a multitude of studies, there is no evidence for a harmful effect of aluminium salts at the low concentrations present in vaccines and food. Although these are not "natural compounds", aluminium salts are harmless at the administered concentrations, and in any case the alternative of not vaccinating is far worse.

Vaccines are associated with health-threatening side effects

As with any therapy, vaccines have some side effects such as pain, low-grade fever and more. More serious side effects such as febrile seizures are much less frequent, and death is an extreme rarity. Eventually, if we weigh these against the potential complications of the disease against which vaccines are given, vaccination turns out much more advantageous. An excellent example was the Japanese outbreak of whooping cough in the late 1970s. The Japanese medical system managed to achieve a vaccination rate of 80% against this disease. In 1975, Japanese authorities decided to terminate vaccination against whooping cough in the face of public criticism of the side effects (mostly fever). In the subsequent three years, whooping cough morbidity rate increased dramatically (more than 30 times) together with reports of infant deaths (more than 10 times). Several years later vaccination was resumed. Of note is the fact that despite relatively high rates of side effects (fever, crying and in extreme cases seizures) there were no reports of death associated with the vaccine. In conclusion, taking the potential side effects and the rare complications into consideration, the alternative is far worse.

Most diseases against which we are vaccinated have died out anyway.

While it is true that most of these diseases have been almost completely eradicated (much to the credit of vaccination), it is the "herd effect" which currently protects the population against them. When a high proportion of the population is immune to a disease, the infection rate is very low with very few outbreaks, if at all. A drop in vaccination rates may bring about new outbreaks, as was the case with the whooping cough outbreaks of the late 1970s.

The infant immune system cannot withstand the load of vaccines to which it is exposed.

An infant's physiological capabilities shouldn't be underestimated. The vaccines an infant receives stimulate a very small proportion of an infant's immune capacity, which can handle about 100,000 different organisms. And again, if a non-vaccinated baby becomes infected with diseases such as diphtheria or tetanus, his immune system stands a much lower chance of winning the battle because of the long time it takes to muster an appropriate immune response (about two weeks). Vaccines greatly shorten this time span and enable the immune system to fight off the invader immediately before it propagates and harms the baby.

Vaccinated people become sick more often.

This is a classical argument which really distorts the truth. Let's take for example a population of 1000 people, 0.5% of which have not been vaccinated against pertussis (5 people). Let us assume that one of these people is a pertussis carrier and the vaccine efficiency is 95%. On average, in such a population 50 vaccinated people would become sick, compared to only five people in the non-vaccinated group. This ten-fold difference may be waved by anti-vaccination advocates as evidence for how vaccines harm our protection against the disease. But if we look at the details more carefully we can see that the two groups are different in size, and that while only 5% of vaccinated people became sick, all non-vaccinated people were infected. Hence, the higher the percentage of people abstaining from vaccination the higher the total infection rate.

Vaccinated people protect us from disease.

People who abstain from vaccination themselves, or worse, those who don't have their children vaccinated, hide in the shade of the herd effect. As long as the proportion of vaccinated people is high enough, we can assume that the chances for an outbreak are low, since the rate of infection is low. Hence, a non-vaccinated individual would benefit from herd immunity. Nevertheless, no vaccination is 100% foolproof (studies indicate an efficiency level of 80-95%). This means that the greater the percentage of vaccinated people, the lower the chances of being exposed to a disease and infected by it. Each non-vaccinated individual raises the probability of a vaccinated person being infected, a disgraceful act of selfishness that risks the weaker groups in the population – infants and the elderly.

The triple vaccine shot (MMR) may lead to autism.

This is a classical case of sloppy and even dishonest science (see the how (not) to perform science video), which has lead to false conclusions that affected large populations. In 1998 a British physician by the name of Andrew Wakefield published a study linking the MMR (measles, mumps & rubella) vaccine to autism and bowel disease in children. This report of course led to a great public uproar and a great number of people called for terminating the use of this vaccine. Following this, a multitude of studies were performed and published in leading science journals, not showing any link between autism and the MMR or any other vaccine. Concomitantly, several major problems in Wakefield's study began to surface, and his study was eventually retracted from the journal which had published it. Today's scientific consensus is that there is no evidence linking the MMR vaccine (or any other vaccine for that matter) to autism.

Vaccine clinical trials are not well controlled due to lack of a placebo group.

When the effectiveness of a new therapy is examined it must be compared to placebo treatment in order to verify that the benefit is not due to a psychological effect. However, treating an individual with a placebo vaccine may leave him/her unprotected from the disease. Therefore, new vaccines are usually tested in comparison to old vaccines against the same disease. This is most commonly done with seasonal flu vaccines. Another issue is that placebo treatment may reach an effectiveness of up to 30%. Most of today's vaccines are 80-95% effective, much greater than the placebo effect. When a new vaccine is introduced for a disease without any previous vaccines, placebo groups are employed in the clinical trial.

Infection with the actual pathogen is more effective than vaccination.

First of all, this is not always true. Several studies have shown that some vaccines are in fact more effective in stimulating the immune system than being infected with the disease. Second, while it is possible that getting infected may lead to a more powerful immune effect, this may entail disease-related complications. Even chicken pox and measles, two supposedly mild childhood disease, may lead to severe complications, and the child may end up with life-long health problems alongside the "natural" immunity. In addition, when some childhood diseases strike for the first time during adulthood they are much more severe. Finally, there is no contradiction between natural immunity and vaccine immunity. Take for example a person who is exposed to a virus against which he was previously vaccinated. The immune system would act up against the pathogen faster and with superior effectiveness, boosting the immunity against the virus while minimizing the severity of the symptoms.

In summary, vaccines have led to a dramatic decline in the prevalence of many infectious diseases, with some having been virtually eradicated. The termination of this immensely valuable medical practice would lead to the outbreak of many diseases, some of which in a more dangerous form. Those most affected would be infants and the elderly. Before one decides to avoid vaccination, he/she should consult authorized medical personnel in order to obtain the most relevant and up-to-date information and to refrain from simply following the latest trends. In the process of writing this article I have visited different "natural" forums and have come across people who do not have their children vaccinated for various reasons. Here is one of the comments I have read that really sums up the essence of things: a forum member consulted her friends whether or not she should have her young daughter vaccinated prior to a trip to India. One of the replies she received was as follows: "I once knew a person who did not return from a trip to South America because he chose not to be vaccinated (against meningitis)". By the way, that woman finally decided to give her daughter homeopathic vaccines, which is equivalent to treating her with water (read "The memory of water" – between science and homeopathy).

Erez Garty
Department of Biological Chemistry
Weizmann Institute of Science


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