The Truth About Vaccines

The Truth About Vaccines

by Dr. Simona Giunta, Ph.D.

Vaccines: What You Should Know.
The 11 Most Common Questions About Vaccines

Know Science believes that knowledge of science can empower people to make better decisions for their health and lives. When it comes to vaccines, that decision could mean life or death.

Breaking news today shocked the world. A six-year-old Spanish boy who had been infected with Corynebactuerium diphtheria earlier last month succumbed to diphtheria [1]. This is the first case of diphtheria in Spain in 29 years since widespread vaccinations have allowed successful eradication of the disease worldwide. The boy, however, was not vaccinated against diphtheria because his parents were against him getting inoculated amidst controversies over the vaccine’s potential side effects. In the small Spanish town of Olot, 10 more people, of which 9 were children, were exposed to the bacterium but did not develop the disease as they were all vaccinated.

To avoid the re-occurrence of preventable disease, we would like to address many concerns that parents may have regarding vaccines, to which research has the answers.

In this series of questions and answers, you will find key facts about vaccines, based on rigorously tested scientific and epidemiological evidence.

In the last five years, there has been a decrease in the number of parents vaccinating their children [2].  So what?

Approximately 800 children die per year as a result of parents not vaccinating their children. Two people in the United States alone die every day of causes that could have been prevented by vaccinations [3].

What about the potential risk of deaths from vaccination?

Severe reactions to vaccination are extremely rare. As with any drug or medicine, there is a small chance that vaccines may cause an adverse reaction. Every year in the United States, millions of people are vaccinated for a wide range of diseases and fewer than 1% have non-life threatening allergic reactions to the vaccine. The rate of death or severe reactions to vaccines, for instance, the MMR shot, is less than one in a million vaccinations [4]. The rate is so low that it is actually difficult to be certain that the adverse reaction was directly linked to the vaccine [4]. To put that in perspective, Tylenol poisoning kills more than 100 people every year [5].

What about the lives that vaccines save?

Vaccines save millions of lives worldwide every year. Perhaps the most impressive result of a vaccination can be seen with the smallpox vaccine. In the past, approximately 80% of children and half of the adults infected with the smallpox virus died of this devastating disease. Two million people died every year during the 1960s from smallpox. The last smallpox case was diagnosed in 1977 [6]. Aggressive vaccination campaigns led to the complete eradication of the disease – that’s right, nobody in the world is infected with smallpox these days! Thanks to this vaccination, the world went from 2 million deaths to zero in less than 10 years.

What about mercury and other potentially toxic substances contained in vaccines?

Mercury hasn’t been used in vaccines since 2001. All routinely recommended childhood and adult vaccinations and most influenza vaccines to date, do not contain mercury. While there may be other ingredients in vaccines, such as preservatives, stabilizers, and enhancers, they are all FDA-approved [7].

Vaccines can contain small amounts of formaldehyde and aluminum but the amount of these substances in vaccines is several hundred times lower than what we are routinely exposed to in our diet, which is the same exposure for traces of mercury in some flu vaccines [7].

Do vaccines cause autism, ADHD, and other non-lethal disorders?

No link has been proven between autism and vaccines. Since the 1950s, mass vaccinations of millions of infants and adults have prevented thousands of deaths [8]. The fraction of children affected by autism is currently 1 in 68 which means that just 1.7% of children suffer from autism. Right now, approximately 90% of children receive vaccinations. Based on these data, vaccines are unlikely to be the distinguishing factor that confers susceptibility to autism.

Why do people say there is a link between vaccines and autism?

The unfounded link emerged from a fraudulent scientific study that kick-started much of the largely unfounded mass hysteria about vaccines that we experience today [9].  The study was retracted and the doctor responsible for the fraud was banned from future research [10]. By then, however, the damage had been done. After the fabricated study was reported, many labs attempted to find evidence for a link between vaccines and autism without success, which further discredits the original “research” [10]. There have been hundreds of studies showing with great statistical significance and confidence that there is no link between vaccines and autism.

I don’t like the fact that my newborn child has to get multiple vaccination shots. Is it harmful for the baby?

Newborns are tougher than you think! The amount of immune challenges young children fight daily is a thousand times greater than all life-time vaccination doses combined. At birth, the passage from the secure environment of the womb through the bacteria-filled vaginal canal is a shock to the baby’s immune system – a good shock! Caesarean birth has been associated with higher risk of allergies, asthma, and inflammation  later in life because the baby is not exposed to these immunity-promoting bacteria [11]. Vaccines have a similar effect. Challenging infant immune systems with vaccines is a safe way to protect them against preventable diseases [12]. Since we live in an environment that offers fewer challenges to the immune system (where we over-sterilize and don’t “let the babies play in mud anymore”), vaccinations are actually a great way to exercise the immune system and keep all its parts functioning properly.

Are vaccines makers just making money from vaccinations that are not actually for our own good?

Most vaccines are cheap for patients. The evidence for the benefit of vaccines is so overwhelming and the consequences of not vaccinating so catastrophic that vaccines made by many pharmaceutical companies are low in cost [13,14].

Are you are saying that I should vaccinate my children? 

Yes! Decades of scientific and medical research have made it possible for us to virtually eradicate diseases preventable by vaccinations. In the last century, childhood mortality in developed countries has decreased to 99% largely due to vaccines and antibiotics [15]. Many charities, foundations, and organizations promote the importance of immunizations for preventable diseases in developing countries. Why would leading nations that have worked to advance science and human health through vaccine discovery want to stop taking advantage of that?

Shouldn’t we let parents be free to make their own choice about vaccinations?

Disease protection derived from vaccines doesn’t work on individual choices, it must be a collective effort involving all the members of a society (especially, in the globalized world of today). Vaccination rates must stay high to keep a whole community protected from a certain disease, a concept called ‘herd immunity’ [16]. The rates required to continue preventing outbreaks and epidemics of certain diseases are variable, with 85% immunization rate needed to protect us from polio and 95% required to eradicate the highly contagious and deadly measles. People with the highest risk from these diseases are young children, immune-compromised individuals, such as cancer patients, and the elderly. Our need for each individual to vaccinate is even greater to ensure that the whole community, especially those with the highest risk, remains healthy. Vaccinations are not about individual choices but about social responsibility and safety.

OK, I see the benefits of vaccines but are all vaccines equally necessary? For instance, what about the seasonal flu?

Influenza is the 7th most deadly disease in the United States right behind diabetes.  Every year, 55,000 adults and children die from the flu and pulmonary complications derived by the flu. Severe adverse reactions to the flu shot are 0.00000001%, so why not vaccinate? Also, remember the concept of herd immunity discussed above. Not vaccinating against the flu means exposing more people to the virus for a prolonged period of time, including immune-compromised individuals. An immunized person that comes in contact with the influenza virus clears the infection in 24 hours. A non-vaccinated person is infected and contagious for almost a week, often asymptomatically at first, which dramatically increases spreading of the disease. It is also important that the flu vaccine is taken yearly.

Annual leading causes of death in USA.

Annual leading causes of death in the USA.

Asking questions about vaccines, just like any other medications, is OK. However, be sure to talk to your doctor, immunologist, or a medical expert on vaccinations. Refrain from drawing conclusions based on assumptions, personal beliefs, or information from unreliable sources. After all, it’s a choice about life —  yours, your kids, and everyone that comes in contact with you in your lifetime. Make that the right choice.


Thanks for reading,

Dr. Simona Giunta, Ph.D.

President of Know Science


This blog was made possible by sharing the knowledge and information collected from several scientists and immunologists and is based on real questions submitted by the Know Science audience. Special thanks to Professor Juan Lafaille, Kate Bredbenner, Danielle Sonnenberg, and Alistair Field for critical reading and expert advice. We welcome any additional questions you may have via our “Ask The Experts!” form and we encourage your comments below.





[3] Further reading on the Center for Disease Control and Prevention website. What would happen if we stopped vaccinations?


[5] American Association of Poison Control Centers. Practice Guideline: Acetaminophen Poisoning: an Evidence-Based Consensus Guideline for Out-of-Hospital Management. Clinical Toxicology, 2006: Vol. 44; pp. 1–18. Wolf SJ, Heard K, Sloan EP, Jagoda AS; American College of Emergency Physicians. Clinical policy: critical issues in the management of patients presenting to the emergency department with acetaminophen overdose. Ann Emerg Med. September 2007: Vol. 50; pp 292-313.







[12] Updated aluminum pharmacokinetics following infant exposures through diet and vaccination. Vaccine 29 (2011) 9538-9543






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