Janci Chunn Lindsay’s claims that COVID-19 vaccines are unsafe are inaccurate and unsupported by scientific evidence

COVID-19 vaccines will cause blood clotting, fertility problems, and immune escape
Inaccurate: The similarity between the human protein syncytin-1 and the spike protein of SARS-CoV-2 is too small to cause concerns about potential cross-reactivity. COVID-19 vaccines aren’t gene therapy as they cannot modify human DNA.
Inadequate support: Evidence indicates that COVID-19 vaccines don’t cause any fertility problems in men or women. Such claims are unfounded.
Flawed reasoning: Preliminary studies suggesting that the spike protein produced during SARS-CoV-2 infection causes blood clotting can’t be extrapolated to COVID-19 vaccines. The level of spike protein produced through vaccination is much lower, and aren’t associated with the same effects during infection. New variants can arise with or without vaccines, but no evidence suggests that COVID-19 vaccines increase this risk. On the contrary, vaccination might reduce the likelihood of new variants emerging by reducing viral spread.
Clinical trials and data from vaccinations under real-world conditions demonstrate that COVID-19 vaccines are very safe and highly effective in preventing disease and transmission. Evidence shows that COVID-19 vaccines aren’t toxic, nor do they impair fertility in recipients. Serious adverse reactions to COVID-19 vaccination are rare among the millions of people who already received it, and the benefits of vaccination far outweigh the few known and potential risks.

FULL CLAIM: “There is a credible reason to believe that the COVID-19 vaccines will cross-react with the syncytin and reproductive proteins in sperm, ovaries, and placenta, leading to impaired fertility and impaired reproductive and gestational outcomes”; “all of the gene therapies [COVID-19 vaccines] are causing coagulopathy”; “there is strong evidence for immune escape, and that inoculation under pandemic pressure with these leaky vaccines is driving the creation of more lethal mutants”


In early August 2021, several posts (see examples here, here, and here) claiming that COVID-19 vaccination will cause fertility problems, blood clotting, and and improve the virus’ ability to evade the immune response (immune escape) went viral on Facebook, Instagram, and Twitter. The posts shared claims made by molecular biologist Janci Chunn Lindsay at a 23 April 2021 meeting from the U.S. Advisory Committee on Immunization Practices (ACIP) in Atlanta, Georgia. This particular meeting focused on discussing the reported cases of blood clotting following COVID-19 vaccination.

During the public comment session, Lindsay gave a three-minute speech calling to halt COVID-19 vaccination over concerns about vaccine safety. Audio recordings and transcripts of Lindsay’s speech went viral on the video hosting platforms YouTube and Bitchute, where they received more than 70,000 views.

Journalist Jennifer Margulis published on her website a transcript with additional comments from Lindsay. Different versions of Lindsay’s claims continued circulating on social media platforms, boosted by this post in Lindsay’s Linkedin profile and periodic interviews in which Lindsay repeated her claims. Some examples are this 14 May interview for the podcast Canadian Patriot and this one on 11 June for the Whistleblower Newsroom podcast.

Lindsay’s speech contained several inaccurate, unsupported, and misleading claims that we will address in this review.

Claim 1(Inaccurate and Unsupported):

“There is a credible reason to believe that the COVID-19 vaccines will cross-react with the syncytin and reproductive proteins in sperm, ovaries, and placenta, leading to impaired fertility and impaired reproductive and gestational outcomes”

This claim is based on the alleged similarity between the genetic sequences of the SARS-CoV-2 spike protein used to develop the COVID-19 vaccines and the protein syncytin-1. This protein allows placenta cells to fuse together for the correct development of the placenta during pregnancy and is also present in sperm[1].

Lindsay claimed that the similarity between both proteins would cause the immune system to detect and attack syncytin-1 within the body of vaccinated people, due to a phenomenon called cross-reactivity. Akiko Iwasaki, an immunologist at Yale University School of Medicine, examined this possibility by analyzing the serum from women with SARS-CoV-2 antibodies induced by infection or vaccination. She found no reactivity to syncytin-1 in any of them.

François Balloux, director of the Genetics Institute at the University College London, showed in this tweet that the similarity between the sequences of the spike protein of SARS-CoV-2 and syncytin-1 is too low to result in cross-reactivity and therefore cannot cause an autoimmune reaction against the placenta. Such a small region of similarity is not unique to the SARS-CoV-2 spike protein and can also be observed in many other human proteins, like hemoglobin, as Health Feedback explained in this review. That review also pointed out that the spike protein of common cold coronaviruses also share small regions of similarity with syncytin-1. If such a small level of similarity was sufficient to lead to an autoimmune reaction against syncytin-1, we would see fertility problems even in people who had the common cold, but this isn’t the case.

Lindsay further claimed that reports of miscarriages and menstrual irregularities in the U.S. Vaccine Adverse Reporting System (VAERS) provide evidence that COVID-19 vaccines might affect fertility. As Health Feedback explained on numerous occasions, VAERS data alone can’t demonstrate whether a vaccine caused an adverse event. This is a misuse of VAERS reports, which simply show that an adverse event occurred after vaccination, but don’t on their own establish a causal link. Demonstrating a causal relationship would require showing a higher rate of the event among vaccinated people than in the general population and a potential mechanism linking the vaccine with the adverse event.

The U.S. Centers for Disease Control and Prevention (CDC) state that “currently no evidence shows that any vaccines, including COVID-19 vaccines, cause fertility problems”. In February 2021, the American College of Obstetricians and Gynecologists, the American Society for Reproductive Medicine, and the Society for Maternal-Fetal Medicine issued a joint statement to the same effect. The American College of Obstetricians and Gynecologists currently states that “claims linking COVID-19 vaccines to infertility are unfounded and have no scientific evidence supporting them”, and recommend vaccination for all eligible people who may consider future pregnancy.

The results of recent studies on this subject are reassuring and don’t indicate that COVID-19 vaccines affect fertility. In June 2021, one study published in Fertility and Sterility Reports used in vitro fertilization frozen embryo transfer to evaluate fertility in vaccinated women, women who were previously infected with SARS-CoV-2, and women who had been neither vaccinated nor infected. The researchers found no difference in embryo implantation and early pregnancy development between the three groups[2]. Another small study published in JAMA found no decrease in sperm count, volume, and motility in 45 men before and after receiving an mRNA COVID-19 vaccine[3].

There is currently insufficient evidence to draw a causal link between COVID-19 vaccination and reports on menstrual irregularities, as Health Feedback explained in this review. The gynecologist Jen Gunter explained in her blog The Vajenda that these effects could be due to the vaccine itself, the immune system response to the vaccine, or other factors such as fever, discomfort, or stress related to vaccination.

To shed light on this question, the U.S. National Institutes of Health encourages researchers to investigate whether COVID-19 vaccines can induce changes in menstruation. In April 2021, Kate Clancy, a professor of anthropology at the University of Illinois Urbana-Champaign, and Katharine Lee, a public health researcher at the Washington University School of Medicine, launched a social media survey to investigate these effects. After collecting more than 140,000 reports on menstrual irregularities, the researchers are now documenting and studying these cases.

Claim 2 (Inaccurate and Misleading):

“All of the gene therapies [COVID-19 vaccines] are causing coagulopathy”

Firstly, the claim that COVID-19 vaccines are gene therapy is inaccurate, as Health Feedback explained earlier in this review. Gene therapy uses viral vectors that provide the molecular machinery necessary to introduce DNA into a patient’s genome to treat a disease. However, gene therapy doesn’t use RNA, and mRNA vaccines don’t use viral vectors, thus invalidating this comparison. Furthermore, RNA from a vaccine cannot directly alter our DNA because it has a very short lifespan and is chemically different from DNA, which prevents it from integrating into the human genome.

Secondly, the claim that the spike protein produced after COVID-19 vaccination will cause coagulopathy (problems with blood clotting) is unsupported and misleading. Lindsay based this claim on a September 2020 study showing that the spike protein produced during SARS-CoV-2 infection can bind platelets and promote the formation of blood clots in an experimental mouse model[4].

Lindsay assumed, without providing any evidence, that the spike protein produced after COVID-19 vaccination would have the same effect. However, the results from the studies evaluating the effect of the spike protein produced during infection are still preliminary. Furthermore, the spike protein from infection behaves differently from that produced by COVID-19 vaccines.

As Health Feedback explained in this review, the level of spike protein induced by COVID-19 vaccination is much lower than levels observed during infection. In addition, most of the protein remains at the injection site without entering the bloodstream. Therefore, while the effect of the spike protein produced during infection deserves further investigation, the claim that COVID-19 vaccines will cause similar problems is unsubstantiated.

While cases of blood clotting have been linked to the Johnson & Johnson and Oxford-AstraZeneca adenoviral vector vaccines, such cases haven’t been associated with mRNA vaccines.

Between March and April 2021, public health agencies received several reports of blood clots among people who received the Johnson & Johnson and Oxford-AstraZeneca COVID-19 vaccines. These reports led the U.S. and several countries in the European Union to pause the use of both vaccines while the cases were investigated. The agencies found a potential link between these vaccines and a rare adverse event called thrombosis with thrombocytopenia syndrome, which involves blood clots with low platelets and particularly affected adult women younger than 50.

However, cases of blood clots following vaccination are very rare and can be effectively treated. Lindsay again misused VAERS reports to suggest that COVID-19 vaccines had caused 338 cases of blood clots with thrombocytopenia as of 9 April 2021. In contrast, as of 11 August 2021, the CDC confirmed only 42 cases, after the administration of more than 13 million doses of the Johson & Johnson COVID-19 vaccine. According to a 16 April 2021 statement by the World Health Organization, the frequency of blood clots among people who received the Oxford-AstraZeneca COVID-19 vaccine was 1 case per 250,000 recipients in the U.K. and 1 case per 100,000 recipients in the European Union.

Indeed, most countries resumed vaccination after the CDC and the European Medicines Agency concluded that cases of blood clots were very rare, and the benefits of the vaccines outweigh their known and potential risks.

Claim 3 (Unsupported and Misleading):

“There is strong evidence for immune escape, and that inoculation under pandemic pressure with these leaky vaccines is driving the creation of more lethal mutants”

In her LinkedIn post, Lindsay compared COVID-19 vaccines with the vaccines developed against Marek’s disease, a herpesvirus infection that occurs in poultry. She claimed that similar to Marek’s disease vaccines, “leaky” COVID-19 vaccines would cause immune escape and the emergence of more virulent variants. She further stated that “it is the vaccinated, not the unvaccinated, who is spreading variants”. Health Feedback reviewed similar claims here and here and found them to be unsupported and misleading.

Angéline Rouers, an immunologist and research fellow at the Infectious Diseases Labs of the Agency for Science, Technology and Research in Singapore, told Health Feedback that this claim isn’t grounded in scientific evidence. She explained that “the rapid vaccination of as many people as possible is crucial to stop the variants. The virus mutates, not because of vaccination but because it is a virus, and every virus in the world can mutate.”

Indeed, all viruses mutate during replication as part of a natural process in viral evolution. The more infections the virus causes, the more times it replicates, increasing the likelihood of generating new mutations that might lead to new variants.

This article in National Geographic explains that the problem with the vaccines against Marek’s disease is that they protect against disease but make almost no difference in the risk of infection compared to unvaccinated poultry. This problem is common in animal vaccines but doesn’t apply to most human vaccines. In addition, Marek’s disease is caused by a herpesvirus. These viruses cause lifelong infections that remain dormant within the body and can reactivate at any time. Because vaccination protects these animals from dying, vaccinated animals that get infected can transmit the virus for life.

But there’s no evidence at the moment indicating that SARS-CoV-2 behaves in the same way. And even though COVID-19 vaccines can’t prevent infection completely, many real-world studies show that they reduce the risk by more than 80%. Furthermore, they are over 85% effective against symptomatic disease. By reducing the likelihood of infection and the amount of virus in the small percentage of vaccinated people who get infected, COVID-19 vaccines are a powerful tool to reduce transmission, making it less likely for the virus to mutate.

However, the spread of the more contagious Delta variant may challenge the ability of COVID-19 vaccines to reduce transmission, according to a new study. Preliminary data from a July 2021 COVID-19 outbreak in Barnstable County, Massachusetts, suggest that viral levels in vaccinated individuals who get infected with the Delta variant might be as high as in unvaccinated individuals[5]. Although the implications of these results for transmission are yet unclear, they suggest that fully vaccinated individuals could potentially transmit the virus to others.

While researchers cannot predict how the virus will evolve in the future, vaccination remains our best tool to reduce the number of infections, and therefore the likelihood that new variants that can evade immunity emerge. In contrast, unvaccinated individuals are more likely to get infected and develop severe COVID-19, increasing the chances of new variants to emerge. Indeed, all the four existing variants of concern to date emerged in 2020, before the start of public vaccination campaigns. This fact contradicts Lindsay’s claim that it is the vaccinated people who are spreading the variants.


Lindsay’s claims that COVID-19 vaccines modify human DNA and will cause infertility due to the similarity of the spike protein with the human protein syncytin-1 are inaccurate. Claims that the spike protein produced after vaccination is toxic and that COVID-19 vaccines will increase the risk of immune escape are unsubstantiated by scientific evidence and speculative at best. No evidence indicates that COVID-19 vaccines cause fertility problems or immune escape, or that the spike protein produced after vaccination is harmful in any way. COVID-19 vaccines have proven very safe and highly effective against severe disease and death.



Published on: 23 Aug 2021 | Editor:

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