Most of the incorrect information we encounter about things like the COVID-19 vaccines represent fear based on understandable misinterpretation of data and statements by scientists. Sometimes, however, spreading misinformation appears to be a deliberate attempt to distort evidence and advance an anti-science agenda. In the latter case, we call it disinformation. It is important to be able to recognize the difference between mistakes and disinformation.
Our colleague Kathleen Hall Jamieson, head of the Annenberg Public Policy Center at the University of Pennsylvania, recently called our attention to a posting by the extreme right-wing site Infowars that made two claims about vaccines for COVID-19 (Note: we’ve included the link but in no way agree with anything you will find there). The first is that the vaccines will ultimately be deadly because of something called “vaccine-enhanced disease” and the second is that the vaccines will prevent women from becoming pregnant.
We’ve seen both of these claims expressed by people who have picked up on information circulating around various media sites. What they have seen is indeed frightening and their own posts reflect both understandable fear and misunderstanding. Let’s look at both claims in more detail and see how Infowars uses them to deliberately turn people away from getting vaccinated against COVID-19. As we will see, Infowars’ claims are exaggerated and filled with untruths: vaccine-enhanced disease and infertility are both very unlikely outcomes of COVID-19 vaccines.
Vaccine-enhanced Disease
Vaccine-enhanced disease is a real thing and a definite concern any time a new vaccine is developed. It occurs when a vaccinated person is exposed to the pathogen (e.g. a virus or bacteria) that causes the disease the vaccine targets. Instead of neutralizing the pathogen, the antibodies raised by the vaccine (and possibly other elements of the immune system) actually assist the pathogen to infect cells and cause even worse disease than seen in unvaccinated people. This is called antibody-enhanced disease or ADE.
The classic case of ADE involves Dengue fever, a viral illness that usually causes mild, influenza-like symptoms. But scientists noted that two populations of people—infants whose mothers had Dengue fever and children who themselves had had a mild case—developed a more severe form of the illness called Dengue hemorrhagic fever if they were exposed to the virus. It is believed in this case that the antibodies either passively transmitted to the newborn or raised during mild symptomatic infection with Dengue fever do not neutralize the virus upon new infection but instead assist viral entry into cells.
ADE caused by vaccines are rare. The two best described instances of vaccine-enhanced disease occurred with a vaccine for respiratory syncytial virus (RSV) and an early form of measles vaccine. A vaccine against RSV, which is a common cause of pneumonia in children, was tested in clinical trials, but vaccinated children experienced worse pneumonia after being exposed to the virus in the community than unvaccinated children and the clinical trials were halted, and the vaccine never released to the public. Scientists are still working to develop a vaccine against RSV for children that will not cause vaccine-enhanced disease.
An early form of the measles vaccine in which the virus was inactivated by formaldehyde also caused more severe illness in vaccinated children when exposed to the measles virus and was withdrawn. The currently used measles vaccine does not cause vaccine-enhanced disease. Nor do any of the other vaccines now given to people.
What we can understand from this is that vaccine-enhanced disease is indeed a real phenomenon and something that must concern scientists developing new vaccines. Because vaccine-induced disease shows up when a vaccinated person is then exposed to the pathogen the vaccine targets, it may not be picked up immediately after a vaccine enters clinical trials, especially when the trial is placebo-controlled and before the blind is broken when no one knows who actually received the active vaccine rather than a placebo. So, it is understandable that if people hear something about vaccine-enhanced disease they will wonder if this could happen with COVID-19 vaccines.
Several lines of evidence make such an occurrence less likely. First, animal studies have so far failed to show any evidence for vaccine-enhanced disease with the COVID-19 vaccines. Second, antibody-dependent enhancement as is seen with Dengue Fever involves a different viral receptor (Fc) than the one used by the COVID-19 virus (ACE2). Finally, no cases of vaccine-enhanced disease have yet been detected among the hundreds of thousands of people who have already received a COVID-19 vaccine. In evaluating the possibility that the COVID-19 virus (SARS-CoV-2) could be involved in vaccine-enhanced disease, a commentator in the journal Science Translational Medicine concluded that “So far, that looks like too narrow a path for the virus to stumble through.”
No one can ever offer an absolute, 100% guarantee that a new medication won’t have some totally unforeseen, serious adverse side effects long after it is thoroughly studied in clinical trials. Our conclusion is that it is unlikely that the COVID-19 vaccines will cause vaccine-enhanced disease. This will of course be monitored, but it should not dissuade anyone from getting vaccinated.
Unfortunately, Infowars represents vaccine-enhanced disease as a major threat and warns people that there is a good chance the vaccines will kill people. You can read the specifics of their claims if you wish—we won’t repeat them here—but it is clear they are massively exaggerated, fear-mongering attempts to convince people not to be vaccinated. While people hearing about vaccine-enhanced disease may reasonably ask if this is a concern for the COVID-19 vaccines, what Infowars does clearly goes beyond anything reasonable. It crosses the line between misinformation and disinformation.
COVID-19 Vaccines and Fertility
The second worry we have frequently encountered is that the vaccines will disrupt female fertility. Here’s the science behind this concern.
There is a protein on the placenta of pregnant women called syncytin-1 that is necessary for a pregnancy to proceed successfully. The claim is that the mRNA in the Pfizer/BioNtech and Moderna/NIH vaccines not only codes for the intended target, coronavirus spike protein, but also for syncytin-1. This would lead the same antibodies that the vaccine induces to attack the virus to also target syncytin-1, thus making it unlikely that a pregnancy could proceed. Once again, we can certainly see how someone reading about this would form a legitimate concern about whether being vaccinated against COVID-19 would compromise fertility.
As in the vaccine-enhanced disease situation, Infowars makes the infertility claim seem like a major, known threat and states that “if it [the vaccine] starts attacking placentas, no one will be able to get pregnant.” Infowars also says that “the syncytin resembles the Spike protein so much.”
There are two things that can be said about these dramatic statements. First, in fact the coronavirus spike protein and the placental syncytin-1 protein are almost completely different. The two proteins share only a few short amino acid (the building blocks of proteins) sequences and therefore it is highly unlikely that antibodies against the virus would be able to target syncytin-1. Second, women enrolled in the vaccine clinical trials did in fact become pregnant. In the Pfizer/BioNtech trials, the only pregnancy with problems occurred in a woman who received placebo.
It is important to acknowledge once again that no one can ever guarantee with absolute certainty that some totally unexpected side effect will occur, even after all the clinical trials are completed for a new drug and many people have taken it without incident. And for now, because of a lack of sufficient data, FDA recommends against pregnant and lactating women receiving the vaccine. That may change once clinical trial data are accumulated with pregnant women receiving the vaccine and for now is a pretty standard FDA decision following the introduction of a new drug. It absolutely does not mean that there is any evidence right now that COVID-19 vaccines will adversely affect fertility.
We see again how Infowars and its like exploit reasonable fears and questions people may have about a health topic by taking things out of context, piling on warnings that have little basis, and exaggerating potential risks. Infowars could just as easily have checked out the vaccine-enhanced disease and fertility claims as we did in writing this commentary. Although sometimes the science can be complex, there are plenty of user-friendly explanations about both things from reliable sources that mitigate fear and worry.
Why would anyone go so far beyond expressing reasonable concerns to the point of active deception? Different disinformation organizations likely have their own reasons, but deliberately spreading incorrect or misleading information jeopardizes the health of individuals and communities. It’s worth fighting hard against.
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