by Vivian Chou
figures by Daniel Utter
If you have been following the 2016 US presidential elections, you are, in all likelihood, aware of the controversy surrounding mandatory childhood vaccination. Vaccines have risen to the limelight in recent years, but their history is much longer than that. Ever since the first vaccination was scientifically documented in 1798 [1], they have reshaped the landscape of human health and medicine. The impacts of vaccines have ranged from the 1979 eradication of polio in the US [2] and the 1980 eradication of smallpox worldwide [3], to prevention of cancer of the liver [4] and the cervix [5]. In fact, vaccines have been so influential that some scientists consider them among the greatest successes in public health [6].
But not everyone shares this optimistic view of vaccines. Today, anti-vaccinationists (sometimes known as “anti-vaxxers”), who include parents, politicians, religious leaders, and more, strongly oppose vaccination, particularly childhood vaccination. At its core, the anti-vaccination movement argues that vaccines are unnecessary, ineffective, or dangerous. But is this truly the case? A closer look at the evidence surrounding vaccinationists suggests that while the anti-vaccinationist ideals are compelling, a more accurate picture of vaccination may be found elsewhere.
What vaccines do: the science at the heart of a controversy.
When a pathogen [7], such as harmful bacterium or virus, infects the body for the first time, the immune system [8] will quickly recognize it as an “invader” based on molecular features specific to the pathogen (known as antigens) (Figure 1A). In response to these antigens, the body produces molecules called antibodies [9] that enable our immune system to track down and kill the pathogen.
The first time the body encounters a pathogen, it takes days to assemble enough antibodies to defeat the infection. In that time, the pathogen has the opportunity to attack the body, causing us to experience symptoms of illness. After this first encounters, the body will memorize what the antigens look like, so that if the same pathogen strikes again, we will be able to launch a stronger, faster defense against future invasions.
Vaccines teach the body to recognize a pathogen. Specifically, vaccines contain the same antigens as pathogens (Figure 1B), but in a weakened or dead form, so that the body can learn what the pathogen looks like and produce antibodies (Figure 1C) in a safe and comparatively controlled manner. Thus, when the body encounters the real pathogen, it is already trained and ready to eliminate the pathogen before it can do any damage (Figure 1D).
Importantly, a vaccine protects not only the individual to whom it is administered, but also the entire population. When the number of immunized individuals within a population reaches a critical threshold, herd immunity [10] is conferred (Figure 2). Herd immunity protects the entire population, even those who are not vaccinated are protected from disease. The percentage of the population that must be immunized to achieve herd immunity varies for individual diseases, with thresholds for common diseases ranging from 75-94% [11]. Herd immunity is crucial to protecting those who are not eligible for vaccines, such as infants, pregnant women, and immunocompromised adults. This means that while vaccines may seem like a personal choice, vaccination protects the entire population—and accordingly, failure to vaccinate could have negative population-level consequences.
Are vaccines truly that effective?
Though no vaccine is 100% effective, many come quite close. For instance, two doses of the chickenpox vaccine are 98% effective against any form of chickenpox [12]. In fact, many vaccines against deadly diseases – such as smallpox [13], yellow fever [14], measles [15]- are over 95% effective, as long as they are administered on schedule. History has also attested to the effectiveness of vaccines. Immediately following the licensing of the measles vaccine in 1962, the number of measles cases in the US dropped dramatically [16] (Figure 3).
Some anti-vaccinationists have claimed that the decrease in measles shortly after the vaccine was introduced is purely coincidental, and that other measures, such as improved hygiene and sanitation, are mainly responsible for the decline in measles and other than diseases. If this were true, we would expect all diseases to have begun their most drastic declines around the same time. However, the sharpest drop in polio cases occurred shortly after the licensing of the polio vaccine in 1955 [17], in the late 50’s — years before the measles decline occurred (Figure 2). Similarly, cases of rubella declined sharply after 1969 [18], when the vaccine was first licensed (Figure 3).
The observation that a decline in the number of disease cases occurs right after the introduction of the vaccine for that disease argues very strongly that it is, indeed, the vaccine which is responsible for the reduction in disease. While improvements in sanitation and healthcare were doubtless beneficial, the availability of vaccines was still the major determinant of the spread of a disease.
A tale of autism and vaccines
Among the most popular arguments within the anti-vaccination movement is that vaccines can do more harm than good – for instance, by causing autism [19], a developmental brain disorder known to impair social interaction and communication.
This argument was popularized by British surgeon Andrew Wakefield [20], “the father of the anti-vaccine movement” in his 1998 article in The Lancet [21] that claimed a link between autism and the measles, mumps and rubella (MMR) vaccine. The article describes a study of twelve children who had begun exhibiting symptoms of autism, as well as gastrointestinal issues, shortly after receiving the MMR vaccine [22]. The paper, and Wakefield’s bold assertions to the media of an MMR-autism link, sparked immediate controversy and quickly became a rallying point for parents opposed to the MMR vaccine, or vaccinations in general.
Within months of the Wakefield study, other scientists conducted independent investigations, which failed to corroborate Wakefield’s findings [23]. Additional studies from the UK in 1999 [24], Finland [25] and Denmark in 2002 [26], and Japan in 2005 [27] similarly failed to confirm the Lancet article. In 2014, Australian scientists analyzed the combined results of ten prior studies — collectively involving over 1.2 million children — and similarly found no relationship between vaccines and autism [28]. Most recently, a US study published in April 2015 has once again shown that the MMR vaccine does not increase the risk of developing autism, even for those who are genetically predisposed to the disorder [29].
In 2004, British investigative journalist Brian Deer presented evidence that Wakefield may have falsified data in his publication [30]. Questions against Wakefield’s findings continued to mount, until January 2010, when the General Medical Council ruled that Wakefield guilty of serious misconduct [31], and the Lancet retracted the original 1998 article [22]. A few months later, Wakefield was removed from the UK medical register and barred from practicing medicine in the UK [32].
The enduring popularity of the autism-vaccine story may be fueled by stories within the anti-vaccination movement itself. Parents have shared stories of children who began developing signs of autism shortly after receiving vaccines, and conclude that vaccines are in fact the cause of autism. However, the onset of autism typically occurs at 2-3 years of age [19], which is around the same age that children receive most of their vaccines.
Additionally, anti-vaccinationists supporting Wakefield’s views often point to the rise of autism diagnoses in the US [33] – more than ten-fold what it was in the 1970s and 1980s – as evidence of an autism-vaccine link. In actuality, the causes of the increase in autism diagnoses are far more complex.
The rise in autism diagnoses is due, in part, to changes in the definition of autism. In general, the definition of autism has become increasingly detailed and inclusive, and thus, more children today are diagnosed with the disorder [34]. In fact, the same symptoms that would be considered “autistic” today may have led to a different diagnosis, such as mental retardation, several decades ago.
Interestingly, the city of Yokohama, Japan has not administered the MMR vaccine to any children born since 1993. Yet, autism rates have increased even among these unvaccinated children [27]. Thus, even as scientists continue to untangle the exact causes of autism, one thing remains unchanged: no one has yet found a scientifically sound and robust link between vaccines and autism.
Are there dangers of vaccines beyond autism?
Besides autism, anti-vaccinationists are often wary of other potential ill effects of vaccines. In some cases, these concerns are reasonable. Many vaccines are not recommended for individuals who have serious allergies to the ingredients, and for those with a weakened immune system due to diseases such as HIV/AIDS or cancer [35]. Additionally, the seasonal flu vaccine can cause life-threatening symptoms in people with Guillain-Barré syndrome [36]. In rare cases, shoulder injury related to vaccine administration (SIRVA) [37], causing prolonged pain and stiffness, can result when vaccines are injected too high up on the arm. However, while there are certainly situations where vaccines can cause severe side effects, they are quite rare.
The most common side effects of vaccines, such as discomfort at injection site, fatigue, and fever, are minor and temporary [38]. Fevers can very occasionally worsen into seizures after vaccination [39]. While many parents worry that fever or febrile seizure are dangerous, neither is life-threatening nor permanently damaging. Febrile seizures are not rare: up to 5% of children experience them within their lifetime when they experience fevers from a variety of causes, such as the flu and cold — not just from vaccines [40]. In fact, vaccines may even prevent febrile seizures, as they protect against many diseases associated with febrile seizures, such as measles and chickenpox, among others.
Conclusion
For many, the question of whether or not to vaccinate is a daunting one. The vaccination debate is plagued with a myriad of contradictions and conflicts, and it can be difficult to navigate these turbulent waters. However, with careful investigation and analysis of the available evidence, an accurate picture may begin to take shape.
Vaccines, like any other medical technology, have advantages and pitfalls alike. History and science have repeatedly shown that the advantages of vaccination far outweigh the pitfalls, and that many of the negatives can be avoided with proper judgment. Yet mistrust of vaccines has persisted, despite ample evidence that they are safe, potent, and effective, and further evidence that soundly counters claims such as causing autism. And despite all the vocal opposition to vaccines, none of the attempts to prove the ineffectiveness or dangers of vaccines have stood up over time and rigorous testing.
Many questions in science and medicine are confusing and frustrating, but fortunately, the question of vaccination need not be one of them. Because for vaccines, the verdict is already in: guilty of being safe, effective, powerful, and highly recommended.
Vivian Chou is a Ph.D. student in the Biological and Biomedical Sciences Program at Harvard Medical School.
Selected references for further reading
”Pathogen.” Science Daily. Accessed December 2015.
Zimmermann, KA. “Immune System: Diseases, Disorders, and Functions.” Livescience. October 2014. Accessed December 2015.
Willingham, E & Helft L. “What is herd immunity?” www.pbs.org. September 2014. Accessed December 2015..
”Vaccines are effective.” www.vaccines.gov. Accessed December 2015.
”What is autism?” www.autismspeaks.org. Accessed December 2015.
Deer, B. “Andrew Wakefield and MMR: the investigation.” The Sunday Times. February 2004. Accessed December 2015.
Willingham, E. “Increase in autism diagnoses not an increase in autism. Forbes. www.forbes.com. July 2015. Accessed December 2015.
”Childhood vaccines and febrile seizures.” CDC. www.cdc.gov. Accessed December 2015.
Full list of references
[1]Riedel, S. “Edward Jenner’s historical invention of the smallpox vaccine.” Proc Bayl Univ Med Cent. 2005.
[2]”Keeping the US polio free.” CDC. www.cdc.gov. Accessed December 2015.
[3]”Smallpox.” WHO. www.who.int. Accessed December 2015. .
[4]”Hepatits B.” WHO. www.who.int. Accessed December 2015.
[5]”HPV vaccine information for young women.” CDC. www.cdc.gov. Accessed December 2015.
[6]Schlenoff, DC. “What are the 10 greatest inventions of our time?” Scientific American. www.scientificamerican.com. November 2013. Accessed December 2015.
[7]”Pathogen.” Science Daily. www.sciencedaily.com. Accessed December 2015.
[8]Zimmermann, KA. “Immune System: Diseases, Disorders, and Functions.” Livescience. www.livescience.com. October 2014. Accessed December 2015.
[9]Mandal, A. “What is an antibody?” News Medical. www.news-medical.net. Accessed December 2015.
[10]”Community immunity (“herd” immunity).” NIH. www.niaid.nih.gov. Accessed December 2015.
[11]Willingham, E & Helft L. “What is herd immunity?” PBS NOVA. www.pbs.org. September 2014. Accessed December 2015..
[12]”Varicella vaccine effectiveness and duration of protection.” CDC. www.cdc.gov. Accessed December 2015.
[13]”Smallpox fact sheet: vaccine overview.” CDC. www.cdc.gov. Accessed December 2015.
[14]”Yellow fever.” WHO. www.who.int. Accessed December 2015.
[15]”Measles vaccine.” CDC. www.cdc.gov. Accessed December 2015.
[16] ”Vaccines are effective.” www.vaccines.gov. Accessed December 2015.
[17] ”Poliomyelitis.” CDC. www.cdc.gov. Accessed December 2015.
[18] ”Rubella.” CDC. www.cdc.gov. Accessed December 2015
[19] ”What is autism?” Autism Speaks organization. www.autismspeaks.org. Accessed December 2015.
[20] Ziv, S. “Andrew Wakefield, father of the anti-vaccination movement, responds to the current measles outbreak for the first time.” Newsweek. www.newsweek.com. February 2015. Accessed December 2015.
[21] in The Lancet journal. www.thelancet.com.
[22] Wakefield, A, et al. “RETRACTED: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children.” Lancet. 1998.
[23] Peltola, H, et al. “No evidence for measles, mumps, and rubella vaccine-associated inflammatory bowel disease or autism in a 14-year prospective study.” Lancet. 1998.
[24] Taylor, B, et al. “Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association.” Lancet. 1999.
[25] Mäkelä, A, et al. “Neurologic disorders after measles-mumps-rubella vaccination.” Pediatrics. 2002.
[26] Madsen, KM, et al. Population-based study of measles, mumps, and rubella vaccination and autism. N Engl J Med. 2002.
[27] Honda, H, et al. “No effect of MMR withdrawal on the incidence of autism: a total population study.” J Child Psychol Psychiatry. 2005.
[28] Taylor, AL, et al. “Vaccines are not associated with autism: an evidence based meta-analysis of case-control and cohort studies.” Vaccine. 2014.
[29] Jain, A, et al. “Autism occurrence by MMR vaccine status among children with older siblings with and without autism.” JAMA. 2015.
[30] Deer, B. “Andrew Wakefield and MMR: the investigation.” The Sunday Times. February 2004. Accessed December 2015.
[31] Triggle, N. “MMR scare doctor ‘acted unethically,’ panel finds.” BBC. news.bbc.co.uk. January 2010. Accessed December 2015.
[32] Meikle, J and Boseley, S. “MMR row doctor Andrew Wakefield struck off register.” Guardian. May 2010. Accessed December 2015.
[33] Dohemy, K. “Autism cases on the rise; reason for increase a mystery.” WebMD. www.webmd.com. March 2008. Accessed December 2015.
[34] Willingham, E. “Increase in autism diagnoses not an increase in autism. Forbes. www.forbes.com. July 2015. Accessed December 2015.
[35] ”Who should NOT get vaccinated with these vaccines?” CDC. www.cdc.gov. July 2011. Accessed December 2015.
[36] ”Guillain-Barré syndrome.” MayoClinic. www.mayoclinic.org. Accessed December 2015.
[37] Zhang, S. “Why are cases of shoulder injuries from vaccines increasing?” Wired. September 2015. Accessed December 2015.
[38] ”Side Effects from Vaccines.” Immunize for good. www.immunizeforgood.com. Accessed December 2015. .
[39] ”Febrile seizures following childhood vaccinations, including influenza vaccination.” CDC. www.cdc.gov. Accessed December 2015. .
[40] ”Childhood vaccines and febrile seizures.” CDC. www.cdc.gov. Accessed December 2015.
Scientific and technological advancements have been growing at unprecedented rates during the last few centuries. With every new step and development, the question of whether society as a whole should adopt this new idea is brought up. Sometimes new isn’t always better, and just because we are able to do something doesn’t necessarily mean we should. Other times, these new technologies have the potential to save thousands of lives. This is the case for vaccinations. There are people that support vaccinating children, and groups that oppose vaccinating children. I propose the policy that every child in the United States is required to receive every vaccination that the Center for Disease Control and Prevention recommends every year.
The benefits of a widespread policy like this across the nation will clearly outweigh the drawbacks.
According to the CDC, “The diseases vaccines prevent can be dangerous, or even deadly. Vaccines reduce your child’s risk of infection by working with their body’s natural defenses to help them safely develop immunity to disease”(Centers for Disease Control and Prevention). Vaccinations are a way that help boost our bodies natural immune system in order to prepare for diseases that could potentially cause a lot of harm to us. Receiving a vaccine against these harmful diseases is very much recommended by most medical professionals. Vaccines save approximately 2.5 million kids from preventable diseases each year (Shot@Life). Vaccinations allow humans to help protect our children from harmful illnesses by preparing their bodies to fight a familiar intruder. These numbers are staggeringly in favor of vaccinations, and suggest that if they were not common, that hundreds of thousands of children would have suffered and potentially died from these very preventable illnesses. An additional argument for the large scale requirement of vaccinations that aid our bodies in becoming immune to harmful diseases is that the side effects of vaccines are rare. A big argument against vaccinations is that they are tied closely with bad side effects.Herd immunity is when the majority of a population (75%-94% depending on the disease) is immunized and therefore a disease will not be dangerous on a large scale to that society (Willingham). This concept of herd immunity takes vaccinations from being a strictly personal decision, to a decision that could potentially impact a lot of people in your life. The choice to not be vaccinated can seem like it only impacts that individual, but it could potentially have negative impacts on a larger scale. The majority of people that can be vaccinated should be vaccinated because there are groups of people – infants, pregnant women, immunocompromised individuals – that cannot be, but still need to be protected from these diseases (Chou). If all that is needed to slowly rid the country of horrible diseases is vaccines, then why shouldn’t they be required for every child to have, regardless of their situation? Vaccinating children is a simple solution that can help contribute to solving the larger problem of handling harmful diseases.
However convincing the pro-vaccine arguments are, there is a side that believes that citizens of the United States should not be forced to be immunized. An argument is that some vaccines are linked to autism. Thiomersal, a trace ingredient found in some vaccines, was removed from vaccines in the US, UK, and Europe as a precaution to try and reduce global environmental exposure to mercury from any source (Vaccine Ingredients). Another argument against vaccinations is that they are not equally accessible to everyone. “In the United States, low-income children and children without health insurance can face challenges to receiving vaccinations” (Ethical Issues and Vaccines). Is it fair that the wealthy can buy health?A final argument against mandatory vaccinations is that it infringes on personal and religious freedoms given in the first amendment. Requiring a children to receive vaccines is, “abhorrent to their religious beliefs and/or practices places a significant and undue burden on their free-exercise rights” (McFall). People against vaccinations claim that it infringes on rights given to them in the constitution.
The proposed policy is that it be made a national law that every child who is capable of being safely immunized receives the vaccinations recommended by the CDC for that year. If a family cannot afford vaccinations, then the government will pay what they cannot. It doesn’t matter whether the child is attending public or private school. The sacrifice of some small individual rights will end up helping society more in the long run. 48 states currently allow religious exemptions to vaccines and 20 states allow philosophical exemptions (Malone). Under the new policy, neither of these would be allowed. It is a parent’s responsibility to do all they can to protect their child, as well as the children and people around them. In this case the most effective way to do that is to have their children vaccinated.
What about Dr. William Thompson who was under whistle blower protection? He said they falsifed data on the MMR study, and that there was a correlation? What is what this mis information, Brian Deer, was paid for by the same people who had interested in the vaccine manufacturer? Conflict of interest anyone, also Wakefield’s peer was exonerated of any wrongdoing simply because his insurace had a clause in it to fight the medical board charges and Wakefield’s insurance did not? A typical bias and article not showing these other facts, or just omit them? Shame on you!
I never got vaccinated and I am fine and autism free.
Lucky for you as its a scientifically plausible scenario:
https://www.sciencedirect.com/science/article/pii/S0946672X17308763
How is it millions upon millions of us were vaccinated and have none of these issues, so many of you are having?
So noticing that all my friends and relatives who have been vaccinated are retarded and have autoimmune disorders-also NONE of them are able to have children, is wrong? While my non-vaccinated relatives and friends live happy health lives and bear healthy happy children?
Does Harvard hate the idea of someone thinking? God forbid-we must all bow down to the Medical doctors and trust them, after all their the ones making the money from vaccinating people- they must be as trustworthy as a used car salesmen with no name…
Harvard doesn’t accept intelligent students-they accept the gullible who cannot and will not think about anything that could compromise their almighty dollar.
Do keep in mind that vaccinations are one of the least profitable and most readily available medical practices ever. The 3 injections associated with the whooping cough cost about 100 US dollars, while the treatments for whooping cough may cost an upwards of 10,000 US dollars. It would be much more profitable to just let us get the disease and treat us for it, would it not?
Oh my! But according to the anti vaxxers the treatments of the vaccines’ side affects costs much more!
And everyone would agree that $100 from every child is more than $10,000 from the few children having whooping cough.
I find it very difficult to believe that every vaccinated person you know is reatarded, immunocompromised, AND sterile. Seems more likely that you are using hyperbole to make a point. I myself have been vaccinated and am neither immunocompromised nor retarded(It’s possible I may be sterile but due to the diligent use of contraceptives I wouldn’t know.) Also, the medically accepted term is intellectually disabled not retarded. Using the appropriate term is a good starting point if you want your rhetoric to be more believable.
Disorders arent the problem, IQ lower then room temperature is the problem, I feel you would have experience with that.
Obviously this a very biased article. Any of these so called articles or “research” you read or see you have to 1st find out who funded them and who gets what money.
I know of 3 people (close friends) whom died exactly after 6 months in exactly the same agony and pain right after receiving a Flu Shot (2012)! One of these friends lived in England, 2 in USA.
I have seen perfectly healthy and happy children becoming a vegetable right after getting their so called vaccines!!
I also believe Autism, Alzheimer and many of these newly invented diseases are direct result of the vaccines.
Why don’t people ask questions like why should we inject an Unknown substance directly into our bloodstream? Is there an Epidemic going on?
Why don’t these brainwashed doctors send these vaccines into a lab to be tested first before injuring or killing someone’s baby?
There was a time when they exposed a horse to snake poison or a disease to get the antibodies to be used as “vaccine” a long time ago but these vaccines today are Not anything like that.
Do more research from sources which do not deal with money nor fear.
Thank you!
Hello, if you have specific concerns about specific references, then feel free to state them. Our authors are careful to cite articles written by credible authors from diverse backgrounds, such as government research agencies, academia, and non-profits. We take the time to provide evidence for our claims–please do the same if you would like to assert that autism and Alzheimer’s disease are “invented” diseases that are caused by vaccines.
There are many, many well-respected and unbiased studies that have deemed vaccines to be safe. Feel free to check out the 5 papers suggested here by the CDC (https://www.cdc.gov/vaccines/hcp/patient-ed/conversations/downloads/vacsafe-mmr-color-office.pdf). The Institute of Medicine has reviewed over 1,000 research articles and has come to similar conclusions (http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=13164). And safety tests are in fact performed on vaccines. Just like all drugs, vaccines must be tested in human clinical trials before they can be approved for sale on the market and widespread use. More information about that extensive and rigorous process can be found here: https://www.cdc.gov/vaccines/basics/test-approve.html.
Well I have one thing to say. You may think Vaccines are bad, but say that to all the kids that could have been killed and immobilized by polio. I could have been one of them, you could have been one of them. Vaccines are not perfect, but when I get older I will vaccinate my child no matter the risk because it can be life saving. So before you start making decisions for us the children. We need to make decisions of our own. Thank you for listening, because in the future we will have the greater voice than you.
Vivian, I forgot to ask, what are your credentials in this controversial arena?
Oh im sorry, I guess your reddit and quora education is better then a Harvard students
I would like an opinion from Harvard Med School about the following info:
http://www.nvic.org/cmstemplates/nvic/pdf/live-virus-vaccines-and-vaccine-shedding.pdf
https://www.cnbc.com/2015/03/03/globe-newswire-public-health-officials-know-recently-vaccinated-individuals-spread-disease.html
My gosh how fraught is this issue with controversy!
(1) Neither side is 100% true or false – both sides are a mix of true and false;
(2) I’ve have had the flu twice in my adult life; both times it almost killed me. For several years in between those two times I stopped getting vaccinated due to the bad PR that was emerging; however, after that last case in 2006, I realized I had to minimize my chances of getting the flu again. So I have been getting vaccinated every year since that time. This year, I also got a pneumonia vaccination. And of course I had the myriad of childhood vaccines, and I still get a tetanus shot every five years. I take care of an elderly person, so that is all the more reason to get vaccinated — to minimize the chances of conveying flu virus to her.
(3) One thing surprised me in Chou’s article: she uses correlation to support her argument that vaccinations reduce disease incidence. This is the same “logic” that anti-vaxxers use to “prove” their contentions that vaccinations cause autism. Scientists are forever reminding us that correlation is NOT causation. So the fact that a Harvard Med School PhD student fell into this same pitfall really surprised me. I thought she was “above” that.
Thanks for your comment. It is always good to remember that correlation does not prove causation. However, there is sometimes no other way to do an experiment except using correlation (it would be unethical to just vaccinate some populations of people but not others and see how many die in each group). In these kinds of cases, it is important to consider other factors that might cause the effect you are looking for, which as the author mentions, scientists have done here. It’s not invalid to use correlation in science–it is just important to remember what you can actually conclude and what you can’t and how likely what you observe is to be caused by what you think it is caused by.
This would be true for vaccines and autism, too–if there were a strong correlation, we should be worried, However, the is not. As you can read here, the only evidence that there ever was that vaccines cause autism (which is, indeed a correlation), doesn’t hold up–the correlation doesn’t even exist if scientists look at more people. So while we haven’t done an empirical test to show that vaccines don’t cause autism; she’s saying that there is no evidence that currently exists, correlative or otherwise, that points to vaccines causing autism: “no one has yet found a scientifically sound and robust link between vaccines and autism.”
No, you misread the article; will try to get back to you later.
Not sure what you’re referring to, but there was a typo in my comment, which I’ve now fixed.
No, of course that is not it. I’ll get back to you when I have more time.
OK, here is your statement: “The observation that a decline in the number of disease cases occurs right after the introduction of the vaccine for that disease argues very strongly that it is, indeed, the vaccine which is responsible for the reduction in disease.” THAT is a perfect example of trying to make the case that correlation is causation.
That’s not my statement–that’s a quote from the article (I am not the author). Which is, actually, what I was referring to in the first paragraph of my comment (sorry if that was unclear). While correlation can’t PROVE causation, it’s not always invalid to use correlation as evidence as long as you consider the pitfalls of using correlation as evidence. In the paragraph previous to the one you quote, the author explains why this decrease in disease incidence is unlikely to be due to some other factors. Does this mean that there is not some unknown factor that could cause the decrease in incidence? No–that’s why correlation correlation can’t prove causation. However, given that there are both empirical studies showing that giving someone a vaccine makes them less likely to get the disease (studies/figures on that cited in the first paragraph of that section) and the lack of other reasonable factors that could have reduced the incidence of these diseases, the correlative evidence is strengthened in this case. Notice that the author says “argues very strongly” not “proves” — I think that’s actually a perfect example of drawing a measured conclusion from correlative evidence after considering several angles NOT saying correlation = causation.
BTW- for the sake of transparency, my first comment stated a fact from the article incorrectly because of the omission of a “n’t”
I understand your point, and I am playing devil’s advocate here because I see the anti-vaxxers often using correlation to bolster their arguments too, which is then cited by other scientists as “only correlation, not scientific evidence”. I wish that both sides could consider each other’s arguments more fully and objectively, because honestly, I don’t think either side is 100% correct or 100% wrong.
Thank you for responding.
If you don’t mind sharing, what do you find un-convincing about this article? How do you think her argument is wrong? I agree that it’s important to listen to all sides–especially on issues that are important to public health. So in that spirit, what do you think the scientists are missing in their conversation with anti-vaxxers?
I do not believe they are directly addressing all the evidence that the anti-vaxxers are citing. I will reread the article more critically in hopes of answering your question. Surely you must be familiar with some of their points. Maybe for starters you could look over some of this material and give me your honest opinion. I did post them elsewhere in the comments, but here they are again:
http://www.nvic.org/cmstemplates/nvic/pdf/live-virus-vaccines-and-vaccine-shedding.pdf
https://www.cnbc.com/2015/03/03/globe-newswire-public-health-officials-know-recently-vaccinated-individuals-spread-disease.html
Sorry–I haven’t had a chance to look at these in detail yet, but it is true that live viruses can (albeit rarely) lead to someone who has been recently vaccinated giving someone else the disease. However, I don’t see this as a reason not to vaccinate, as epidemiological studies suggest that these vaccines lower disease incidence overall. Also, the virus in live virus vaccines is weakened, meaning that even if it spreads to another person, it’s much less likely to spread widely than the actual virus (which would spread if people weren’t vaccinated).
Typo — second paragraph — “argues asserts”.
“Within months of the Wakefield study, other scientists conducted independent investigations, which failed to corroborate Wakefield’s findings [23]. Additional studies from the UK in 1999 [24], Finland [25] and Denmark in 2002 [26], and Japan in 2005 [27] similarly failed to confirm the Lancet article. In 2014, Australian scientists analyzed the combined results of ten prior studies — collectively involving over 1.2 million children — and similarly found no relationship between vaccines and autism [28]. Most recently, a US study published in April 2015 has once again shown that the MMR vaccine does not increase the risk of developing autism, even for those who are genetically predisposed to the disorder [29].” ———— Do you know, by any chance, who funded these studies in the other countries? Some anti-vaxxers claim that Big Pharma is behind all the research which has concluded that vaccinations are safe.
Also, have you watched the documentary called “Vaxxed”? It would be great if you or other professionals at Harvard Medical School would address each case they raise, and publish it on this and other websites, to help the general population understand was is true and what is not. That would be most helpful to folks like me who try to keep an open mind.
Thanks! I will fix the typo. Studies usually say who they were funded by (although I realize that that information may be hard to find if it’s behind a paywall), and always have to say if their funding could be considered a conflict of interest (which a vaccine study funded by pharma would definitely fall under). People might argue that these studies would just lie and say they weren’t funded by pharma, but actually two of these studies cited here (#23 and #25) does say that it received partial funding from Merk). #24 was funded by the Medicines Control Agency (part of the UK government), #26 was funded by the Danish National Research Foundation; the National Vaccine Program Office and National Immunization Program, Centers for Disease Control and Prevention; and the National Alliance for Autism Research, and #27 and #28 don’t mention where their funding is from or cite conflicts of interest, #29 is funded by the National Institute of Mental Health, National Institutes of Health, and the US Department of Health and Human Services.
So it’s true that some of this research discounting the Wakefield paper is partially funded by Merk, but it was done at independent university labs, and it would be highly unethical for them to do studies differently because of their funding source. Either way, there are at least five studies funded by government agencies that support these studies, so it’s not true that Big Pharma is behind all of the pro-vaccine studies.
I have not watched “Vaxxed,” but I will see if someone is interested in writing such an article for our website.
Vivian, Please let me know if you can get some professionals from Harvard Med School to watch and respond to “Vaxxed.” I think it’s very important to get that professional, informed response out into the general public. Also, would you please tell me your credentials so that I may properly reference your statements? Thank you!
Hi, I’m not Vivian. I’m the editor in chief of this blog. I am a PhD student in biomedical science.
All this time I thought I was communicating with Vivian. Do you know what her credentials are? And your name please? Thanks, –Dave
Can you tell me the reason you want this information?
I have ongoing discussions with anti-vaxxers, and if I could passing along the credentials of the people I am quoting it would lend more weight to my perspective. That is why I am particularly interested in whatever the professionals at Harvard Medical School have to say on this subject.
Vivian is also a PhD student in biomedical science. Neither of us are doctors. However, we have both read (and have the training to understand) some of the primary literature on this topic. You can find my info here: http://sitn.hms.harvard.edu/sitn-staff/
-Kelsey
Another comment Vivian. To your point: “So it’s true that some of this research discounting the Wakefield paper is partially funded by Merk, but it was done at independent university labs, and it would be highly unethical for them to do studies differently because of their funding source. Either way, there are at least five studies funded by government agencies that support these studies, so it’s not true that Big Pharma is behind all of the pro-vaccine studies.”
It might be highly unethical, but the fact is people do bow to pressure, or to the lure of money. Unfortunately, that is not at all uncommon in the world, especially in the US where money rules over all else.
And that’s the reason they have to declare where the money came from. However, I’d be more wary of a study done by a pharmaceutical company than a study done by an academic lab funded by a pharmaceutical company.
“it would be unethical to just vaccinate some populations of people but not others and see how many die in each group” — This is the only way to know the truth. Unethical is to force others without knowing the truth.
George is right. They did the same thing with other cases in the past, like the AIDS treatments. That leaving people with a placebo would be unethical. This is illogical to the nth degree. There’s nothing “unethical” if we don’t know yet whether the treatment works or not. The study’s GOAL is to know whether it works or not. It’s a very basic logical fallacy.
Also, saying that the placebo group will die is just disingenous and needlessly fatalist. No one instantly dies of measles or flu without a vaccine. It takes a lot of other factors for someone to die from such benign diseases, by today’s standards. The best case scenario is that the placebo patients will treat their disease correctly, build a natural immunity and be immune for life.
I agree with your comment. I think it is important in these situations to remember that correlation does not mean causation. Just like an example I heard in my research class, there may be a correlation in ice cream consumption and drowning related deaths during the summertime, but that does not mean that ice cream causes drownings to occur. There is only an association because people are more likely to eat ice cream in the summer as well as people being more likely to go swimming in the summer. To many people, it could seem like vaccines cause autism or other complications but there may only be correlations between the two. No one will really ever know until there is scientific evidence that can be backed up by research.
Hey. Thanks for the article and citations/sources. This was easy to read, covered major points of interest (based on conversations I’ve had in the past regarding this topic), and something I can pass on to others interested in the topic.
Just to point out a few non-factual errors in the article:
1. “Figure 2.: Herd immunity. (A) When no one in a population is vaccinated, infections can spread rapidly and become an outbreak that.” Might want to fix “that.”
2. A couple copy references to Figure 2 that more likely were meant to say Figure 3; both are under the sub header “Are vaccines truly that effective?”
Thanks!
good things are not forced , what i know is the truth is alway kept secret. vaccines are not safe
you’re wrong and you should feel bad
Vaccines are actually safe. More unvaccinated people died than vaccinated. They are tested for about 7 years, and they know what they are doing