Fact Check

Did a Harvard Study Prove That “Unvaccinated Children Pose No Risk” to Other Kids?

A deceptive and factually challenged blog post on an anti-vaccine website is not a “Harvard study,” yet its false conclusions are popular on social media.

Published Aug. 14, 2018

 (Image Point Fr / Shutterstock)
Image courtesy of Image Point Fr / Shutterstock
A Harvard study proved that “unvaccinated children pose no risk” to other kids.

In 2017, the conspiracy-peddling Neon Nettle junk news website published an article headlined “Harvard Study Proves Unvaccinated Children Pose No Risk.”

The referenced “study” was, in fact, not a study but rather an “open letter” penned by a woman named Tetyana Obukhanych and published on the anti-vaccine website Thinking Moms’ Revolution -- a site that promotes a $2,000.00 "ion detox" machine as a treatment for autism. Obukhanych's letter, first published in 2015, continues to be shared and re-shared online despite its numerous shortcomings.

We will discuss Obukhanych’s academic background toward the end of this post, as such details matter less than the content of the misleading or false claims made in her open letter, which we will address one-by-one. Broadly, Obukhanych argues that laws requiring mandatory vaccinations for schoolchildren are misguided because most vaccines included in such laws (in her estimation) do not prevent the transmission of disease, and therefore an unvaccinated child would pose no added risk to a vaccinated child in a school setting:

It is often stated that those who choose not to vaccinate their children for reasons of conscience endanger the rest of the public, and this is the rationale behind most of the legislation to end vaccine exemptions currently being considered by federal and state legislators country-wide.

I have outlined ... the recommended vaccines that cannot prevent transmission of disease either because they are not designed to prevent the transmission of infection ... or because they are for non-communicable diseases.

People who have not received [these vaccines] pose no higher threat to the general public than those who have, implying that discrimination against non-immunized children in a public school setting may not be warranted.

Obukhanych’s repeated refrain is that accepting (or, more to the point, rejecting) these vaccines “cannot alter the safety of public spaces,” such as schools, because they afford only personal protection. The result is a viral story that provides a highly shareable but flawed justification to parents for use against other parents who accuse them of endangering their children by not vaccinating them. In most cases, Obukhanych’s reasoning is problematic and her conclusions unsupported by science.

Tetanus Vaccination Does Not Prevent Transmission of Tetanus: TRUE

Tetanus, as stated in Obukhanych’s post, is a non-communicable disease. Vaccination against tetanus, which is caused by the release of a toxin produced by C. tetani bacteria, does not prevent the spread of those bacteria; it merely affords one’s body the ability to destroy the toxin they produce.

That fact does mean a child without a tetanus vaccination poses no additional risk to others. It is worth mentioning, however, that 2 in 10 people who develop tetanus die from the disease, and that the tetanus vaccine (which is generally included in a three-vaccine combination) is uncontroversially safe for use in nearly all populations.

Hepatitis B Does Not Spread “In a Community Setting”: FALSE

Obukhanych attempts to make a similar argument against Hepatitis B vaccination, arguing that since it is a blood-borne disease, it is unlikely to be spread amongst children:

Hepatitis B is a blood-borne virus. It does not spread in a community setting, especially among children who are unlikely to engage in high-risk behaviors, such as needle sharing or sex. Vaccinating children for hepatitis B cannot significantly alter the safety of public spaces.

Obukhanych confidently asserts that Hepatitis B does not “spread in a community setting,” but while non-sexual and non-needle based transmissions are rare, they are not impossible, as the disease can be transferred from mother to infant or via cuts. Although the risk of a school-aged child's contracting the disease is lower than an adult’s, the risk to the former of being chronically infected from the disease is significantly higher. Approximately 90% of infants and 25%–50% of children aged one to five years who are exposed to hepatitis B become chronically infected. For adults, around 95% recover completely from exposure to the same disease.

On a population level, the hepatitis vaccine has been clearly successful in reducing the disease burden worldwide, thanks to high vaccination rates globally. While the impact of one child may seem negligible on a broad level, not vaccinating for hepatitis B very much impacts the “safety of public spaces.”

The Hib Vaccine Has Resulted in Other Outbreaks: MISLEADING

Obukhanych’s argument against the Hib vaccine, which imparts immunity against Haemophilus influenzae type B bacteria (a common cause of meningitis, pneumonia, and epiglottitis, but, despite the name, is unrelated to influenza), attempts to make it sound as of the vaccine actively endangers the safety of public spaces. Her argument does so by ignoring entirely the fact that the Hib vaccine has been highly successful at reducing influenzae type B infections and focuses instead on the unproven assertion that several isolated influenzae type A or other “untypeable” strain outbreaks that have occurred since its introduction as a recommended vaccine were caused by vaccination.

To make that case, Obukhanych cites a 2011 paper regarding the increasing incidence of H. influenzae type A diseases in adults in Utah. That paper was one of several which have documented increases in influenzae type-a (or other “untypeable”) infections in localized communities. That paper does not, however, make the argument that this increase (or other similar outbreaks) has a direct causal relationship with influenzae type b vaccinations (although that paper and others have speculated about it). The study explicitly stated that the cause remained unclear: "Several studies in addition to ours suggest an increase in invasive disease caused by to non-type b H. influenzae among adults. The reasons for this change are unclear, and might reflect changes in the organisms, changes in the number of persons at high risk, or perhaps waning of cross-immunity induced by exposure to Hib."

More recent research has still not provided complete answers to that question, but non-type-B outbreaks primarily affect older adult populations and have limited relevance to a schoolyard scenario. What is clear is that vaccination against type-B influenzae has greatly affected “the safety of public spaces.” Before the introduction of the Hib vaccine, about 20,000 children in the United States under 5 years old contracted Hib disease each year, and about 3%–6% of them died. Since the use of the Hib vaccine began, the number of cases of invasive Hib disease has decreased by more than 99%.

Vaccinating for Diphtheria Cannot Alter the Safety of Public Spaces: FALSE

Obukhanych’s argument against the diphtheria vaccine is that it is only good for personal protection. She makes this argument by correctly stating that diphtheria is caused by a strain of bacteria (Corynebacterium diphtheria) and by correctly stating that vaccination does not prevent transmission of those bacteria. This is an impressive bad-faith argument.

Her argument conveniently leaves out the fact that the most dangerous infections associated with the disease are not caused by the bacteria themselves, but through the colonization of them by a virus (a bacteriophage called ß-corynebacteriophage) which induces the bacteria to produce a dangerous toxin. The diphtheria vaccine imparts immunity by preventing the bacteriophage from colonizing C. diphtheria, and this action does two things that directly “alter the safety of public spaces” in a positive way.

First, one result of diphtheria vaccinations is that any C. diphtheria transmitted from one vaccinated human to another are not anywhere near as dangerous as the same bacteria transmitted by an unvaccinated person, since those bacteria not likely to be infected and therefore not likely to be producing the dangerous diphtheria toxoid. Uncolonized C. diphtheria can cause mild illnesses, but nothing close to as severe as true diphtheria. Second, uninfected C. diphtheria bacteria are less likely to be spread between individuals in the first place, meaning the vaccine quite literally reduces the chances that the disease will be transferred between individuals.

In the 1900s in the United States, 76 people per every 100,000 died from diphtheria. Since the diphtheria vaccine’s introduction, fatalities from diphtheria have become nearly non-existent in the United States and other developed countries.

Acellular Pertussis (aP) Vaccine Does Not Prevent Transmission of Pertussis: MISLEADING

Obukhanych’s argument against the acellular pertussis (aP) vaccine is similar to her attempted argument against diphtheria, which is that the vaccine does not prevent transmission of the disease, commonly known as whooping cough and caused by the bacterium Bordetella pertussis:

An experiment with deliberate pertussis infection in primates revealed that the aP vaccine is not capable of preventing colonization and transmission of B. pertussis. The FDA has issued a warning regarding this crucial finding.

That study was big news, as it provided a possible answer to the question of rising cases of whooping cough documented in the United States and other places around the world. The study provided evidence that the acellular pertussis vaccine, which replaced a “whole cell” version of the vaccine in many countries in the 1990s, does not prevent asymptomatic transmission of B. pertussis -- cases in which the bacteria, but not the symptoms created by their infection, are transferred unknowingly between humans.

Although the vaccine prevents the dangerous coughing that can sometimes prove fatal, Obukhanych is correct in stating that it may not prevent the bacteria’s transmission. However, Obukhanych’s characterization of the study as being evidence of harm for which the FDA had to issue a warning is misleading. The authors of that study made it explicitly clear that maintaining a high level of vaccination currently was of utmost importance because of the result: "It is important to note that our data in combination with human data show that vaccination with aP provides excellent protection from severe pertussis. Therefore, any short-term plan for addressing the resurgence of pertussis should include continued efforts to enhance aP immunization."

Responding to similar findings published in 2015, epidemiologist Benjamin M. Althouse told the New York Times that “until we get that vaccine, it is more important than ever to be vaccinated, and we need to keep the vaccination levels high.”

The Inactivated Polio Virus Does Not Prevent the Transmission of Poliovirus: FALSE

Obukhanych’s argument against the polio vaccine is probably the most bad faith of them all. Her broad claim is that the inactivated poliovirus vaccine (IPV) does not prevent the spread of wild polio (the form of the disease that was in circulation worldwide before vaccination) and instead only works in countries such as the United States where polio eradication is complete.

First, such a claim is patently false on its face. The inactivated polio vaccine is, for example, singularly responsible for the eradication of polio in most of the Scandinavian countries, which suggests that it has quite successfully blocked transmission of the disease. Her statement that “wild poliovirus eradication is attributed to the use of a different vaccine, OPV or oral poliovirus vaccine,” is broadly true for the United States, but not for the world as a whole.

Second, Obukhanych misrepresents a study’s results to suggest that it provides evidence the IPV vaccine does not protect against the wild poliovirus. She does this to make the clever-sounding argument that a vaccinated child might pose a risk to unvaccinated children, but she does so by ignoring everything but a single sentence found in a single diagram in a lengthy New England Journal of Medicine study that sought to address the vaccine’s effectiveness against wild polioviruses.

In her post, she references a footnote to a table showing the viral load of the feces of a control group of infants and a group treated with IPV after they were inoculated with OPV. Her interpretation of the figure is that “high counts of live virus were recovered from the stool of children in all groups, [making] it clear that IPV cannot be relied upon for the control of polioviruses.”

In fact, the study’s authors viewed those results as evidence of IPVs success against wild poliovirus strains, which (not to put too fine a point on it) is the opposite of the argument she claims the paper is making (emphasis ours):

In our study, the prevalence of excretion after receiving trivalent OPV was high (more than 90% for any poliovirus) and was similar among all three groups, including the control group, but viral titers were lower in both IPV groups, suggesting an effect of IPV vaccination on replication of polioviruses. These data from stool titers are consistent with a body of literature suggesting that previous vaccination with IPV can reduce the prevalence, duration, and titers of poliovirus in the stool.

The World Health Organization's view tracks that study’s view of IPV as well, stating that it “has been used successfully to eradicate polio in a few countries, notably in Scandinavia and the Netherlands, [and that in the] numerous countries that have been introduced to IPV over the last decade no evidence of continued circulation of poliovirus strains has been observed, indicating that IPV may successfully inhibit community transmission of poliovirus.”

Who is Tetyana Obukhanych?

Obukhanych bills herself as a recovering “mainstream” academic who has seen the error of her field's ways. She claims a PhD in Epidemiology from The Rockefeller University in New York and states on her Patreon page that she “held postdoctoral research training appointments in prominent immunology laboratories affiliated with Harvard Medical School and Stanford University School of Medicine.” Her publication record supports the notion that she held positions at, or worked with, these institutions, though she has few publications to her name.

Despite not being a physician, she is a “Founding Director” of Physicians for Informed Consent (an organization described in multiple science-based medical blogs as a "radical anti-vaccine" group), and she has produced a self-published e-book titled Vaccine Illusion: How Vaccination Compromises Our Natural Immunity and What We Can Do To Regain Our Health. She also sells access to her teleconferenced lectures for $20.00 a month.

Describing her “open letter” published on an anti-vaccine blog as a “Harvard study” is, in our view, quite a bit of a stretch.


Obukhanych, Tetyana.   "Immunologist Tetyana Obukhanych: Unvaccinated Children Pose ‘No Extra Danger to the Public’."     Thinking Moms’ Revolution.   17 April 2015.

Centers for Disease Control and Prevention.   "Diphtheria, Tetanus, and Pertussis (DTaP) VIS."     Accessed 13 August 2018.

Centers for Disease Control and Prevention.   "Hepatitis B Questions and Answers for Health Professionals."     Accessed 13 August 2018.

Meireles, Liliane, et al.   "Three Decades of Hepatitis B Control With Vaccination."     World Journal of Hepatology.   28 August 2015.

World Health Organization.   “Haemophilus Influenzae Type b (Hib) Vaccination Position Paper – September 2013"     27 September 2013.

Rubach, Matthew et al.   "Increasing Incidence of Invasive Haemophilus influenzae Disease in Adults, Utah, USA."     Emerging Infectious Diseases.   September 2011.

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Jalalvand, Farshid, and Kristian Riesbeck.   Plotkin’s Vaccines. Elsevier Health Sciences (Seventh Edition), 2018.   ISBN 032335761X.

Warfel, J.M. et al.   “Acellular Pertussis Vaccines Protect Against Disease but Fail to Prevent Infection and Transmission in a Nonhuman Primate Model."     Proceedings of the National Academy of Sciences.   14 January 2014.

Bakalar, Nicholas.   “Symptom-Free Carriers May Be Spreading Whooping Cough."     The New York Times.   29 June 2015.

Böttiger, M.   “The Elimination of Polio in the Scandinavian Countries."     Public Health Reviews.   1993-1994.

Cuba IPV Study Collaborative Group.   “Randomized, Placebo-Controlled Trial of Inactivated Poliovirus Vaccine in Cuba."     New England Journal of Medicine.   12 April 2007.

World Health Organization.   “Biologicals: Poliomyelitis"     Accessed 13 August 2018.

Alex Kasprak is an investigative journalist and science writer reporting on scientific misinformation, online fraud, and financial crime.

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