As vaccine rollout continues, concerns about vaccines still loom — and it’s important to clarify such concerns and dispel unfounded myths. Among the questions that tend to pop up every now and then is whether vaccines cause infertility or similar types of problems. Thankfully, the experts have some good news.

Where the question is coming from

There is currently no evidence that antibodies formed from COVID-19 vaccination can cause any type of fertility problems. But, as we’ve seen throughout the pandemic, the lack of evidence hasn’t deterred conspiracy theorists to promote their ideas.

We’ve seen it all in the past year: from the “it’s just a flu” and “it’s a man-made virus” to the more recent “vaccines have microchips”. Sometimes, vaccine hesitancy comes from legitimate questions, while other times, it’s just wild conspiracy theories.

The infertility question started in December when German doctor and politician Wolfgang Wodarg teamed up with a former Pfizer employee (conspiracy theorist Michael Yeadon) to ask the European Medicines Agency (the European counterpart of the FDA) to delay the approval of the Pfizer vaccine.

Wodarg is no stranger to COVID-19 controversies. He repeatedly claimed that there’s no real reason to worry about the novel coronavirus, that it’s just one of the many respiratory viruses we’re already used to dealing with. His claims included numerous verifiable falsehoods, and both scientists and the German media were quick to contradict him. Despite his medical background, Wodarg turned out to be just one of the many politicians denying existing science.

Yeadon, on the other hand, is a more curious case. He is an accomplished epidemiologist-turned-antivaxxer, whose story is bound to raise eyebrows.

Not only did Yeadon work 16 years at Pfizer, but he even served as the company’s vice president. Furthermore, Yeadon went on to found a successful biotech company which sold for at least $325 million. He’s not the type of person whose claims you’d dismiss without a second thought — which is why he emerged as an unlikely hero for conspiracy theorists.

Yeadon stepped into the spotlight with a column for the United Kingdom’s Daily Mail, a conservative British newspaper often criticized for its unreliability and for sensationalist and inaccurate stories on science and medical research. In his column in October, Yeadon claimed that the number of cases in the UK would fizzle out and people should be allowed to go about their business normally. The number of cases surged afterward and the disease has since killed about another 80,000 people in the UK. Yeadon’s column has been thoroughly debunked and his former Pfizer colleagues expressed their shock and disbelief at his behavior — but it didn’t come out of nowhere.

Turns out, the former Pfizer scientist was posting multiple erratic tweets, riddled with Islamophobia, racism, and disturbing takes on rape (including that of underage girls). But this didn’t prevent him from becoming a favorite of the antivaxx crowd.

Yeadon has said he personally doesn’t oppose the use of all vaccines, but along with Wodarg, he claimed that vaccines can cause infertility. Their claim was linked to a protein called syncytin-1, which shares some similarities with part of the spike of the new coronavirus. That protein is an important component in the placenta of mammals and, for some unspecified reason, the two claimed that all vaccine trials should be stopped as vaccines can cause infertility. The idea is that some cells in the placenta are so similar to those of the virus that the vaccine-induced antibodies would attack the placenta — but there’s simply no reason to believe that.

Their petition was picked up by the regular anti-vaccination blogs and social media. Facebook and Twitter removed numerous posts for disinformation, but the discussion picked up steam. Do the COVID-19 vaccines cause infertility?

The answer, thankfully, is a resounding ‘no’.

What the experts are saying on COVID-19 vaccines and infertility

Numerous national health agencies, organizations, and medical journals have debunked this idea. Recently, Metafact, a platform that attempts to assess scientific consensus on different topics, also asked experts in the field to comment on this.

“The currently approved Covid-19 vaccines cannot cause infertility. mRNA vaccines are comprised of synthetic pieces of RNA that rapidly get degraded at the site of injection after the RNA chain is translated into amino acids (building blocks of proteins). So there is no chance for the RNA to get anywhere else in the body for it to affect fertility,” says Lee Riley, an expert in expert Infectious diseases, Epidemiology, and Vaccinology from University of California, Berkeley.

“The vector-based vaccine like the newly-approved Johnson & Johnson vaccine uses another live virus (adenovirus) to deliver the Covid-19 coronavirus protein. The adenovirus that’s used in the vaccine will not cause infertility. People are exposed to all kinds of adenoviruses all the time, which cause no symptoms or common cold symptoms.”

Maciej Zatonski, an expert from GlaxoSmithKline, was even more direct.

“There is no evidence that any of the Covid-19 vaccines could cause infertility. There isn’t even a plausible biological mechanism in which this could happen. In fact, many participants of early clinical trials for Covid-19 vaccines later got pregnant and delivered healthy offspring.”

In fact, none of the experts Metafact asked showed even a sliver of doubt. All vaccine ingredients are in the public domain, so it’s easy to check that syncytin-1 is not an ingredient. There simply isn’t enough similarity between this viral component targeted by vaccine antibodies and the placenta to believe that any harm would be done.

Professor Catherine Thornton from Swansea University explains: 

“The similarity between the proteins is insufficient for this to be of any concern. [..]For antibodies to mistakenly recognise syncytin-1 as SARS-CoV-2, there would have to be sufficient similarity of amino acids in these strings (which there isn’t) and the critical amino acids would need to be clustered together in the 3D molecule in a sufficiently similar and accessible way (which they aren’t).”

No link between vaccines and infertility

The idea that vaccines cause infertility has no evidence behind it. It is supported by two people with a medical background, but with a striking history of anti-scientific ideas. Both have been rebuked by the scientific community.

So the observed data disprove the idea, the theory disproves the idea, everything disproves it. The idea that vaccines cause infertility is nothing more than another conspiracy theory in a deluge of disinformation.

All the approved vaccines have passed animal testing and human testing, and neither has shown any effects on fertility. There isn’t even a believable mechanism that would cause these problems. In fact, vaccination can help keep both the mother and the fetus safe. Recently, a US woman gave birth to the first known baby with antibodies after receiving a vaccine at 36 weeks.