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Does the COVID-19 Vaccine Affect Your Sperm?

These sorts of questions are top of mind for physicians who want to quell public concerns around the vaccine

In 1995, shortly after her son William was vaccinated for measles, Rosemary Kessick noticed a change in his behavior. The 15-month-old stopped saying the beginnings of words, so “book” became “ook” and ball became “all.” He also developed an unquenchable thirst, but “juice” quickly turned into “oose” and “oose” into “oo.” That’s until, according to a 2014 BBC interview with Kessick, her son’s words “dissolved” completely.

It was around this time that Kessick decided to call Andrew Wakefield, a former British physician who was getting attention for claiming that there was a link between the measles vaccine and Crohn’s disease. In the same interview, Kessick explains that she “picked up the phone and phoned Wakefield, and said to him, ‘I’m the mother of an autistic child,’ and he stopped me and said, ‘I don’t know anything about autism, I’m a gastroenterologist.’” Still, during that phone call, Kessick told Wakefield of a theory she had developed based on her own observation — that her son’s neurological problems began a few days after he received the MMR vaccine, which protects against measles, mumps and rubella. Her hunch was enough to keep Wakefield from hanging up. 

In 1996, not even a year after their phone call, Wakefield, inspired by his conversation with Kessick, turned his attention to tracking down a ghost. He began researching possible connections between the MMR vaccine and autism. Two years later, Wakefield published the results of a 12-person study linking a novel form of bowel disease, autism and the MMR vaccine in The Lancet medical journal. It was at a press conference soon after that Wakefield would go on to suggest that the MMR vaccine ought to be suspended in favor of individual vaccines for measles, mumps and rubella (a total of six shots). The result, despite a number of studies and researchers disproving Wakefield’s findings, led to a sharp decline in MMR vaccines, giving rise to outbreaks of measles and rubella. 

Far more consequential, and based on a single, tiny, flawed and misguided study that would, time and again, be refuted by nearly every other analysis, a specter was unleashed. Using congenital abnormalities as its bogeyman, the Lancet MMR autism fraud (as it would later become known) would forever haunt public perception around the jab.

As of writing this, more than 11 million people have received at least one dose of a COVID-19 vaccine in the U.S. Common side effects include chills, tiredness and headaches. During medical trials, it’s been reported that four people experienced Bell’s Palsy (partial facial paralysis) after receiving the Pfizer vaccine. According to the briefing, the frequency of Bell’s Palsy in the vaccine group is “consistent with the expected background rate in the general population.” In addition, the researchers identified “no clear basis upon which to conclude a causal relationship at this time.” 

Unrelatedly, the medical examiner’s office in Miami is looking into the death of a doctor who died 16 days after getting the Pfizer vaccine. But again, there’s currently no evidence to suggest that the vaccine is what caused the blood clot that ultimately led to the doctor’s death. 

This all to say that, as things currently stand, the COVID-19 vaccine hasn’t consistently shown serious side effects, and it’s precisely for that reason that the FDA has granted emergency authorization to three different pharmaceutical companies who’ve developed a similar vaccine. But scaremongering around congenital abnormalities, as well as fertility issues, have long been the bread and butter of the anti-vax movement, and it’s not difficult to see why it’s so effective. Merely suggest that a vaccine could have an adverse effect on a child or a person’s ability to have children and the entire edifice collapses. “It’s like taking away someone’s most precious gift,” says Noelle LoConte, a clinical oncologist who last year examined the effects of the HPV vaccine and its effect on fertility. “So why would you risk it?”

The task of quelling public concerns around any vaccine, particularly as it relates to fertility, is particularly complicated, according to LoConte. “It’s a complex scientific question to answer because it’s having to prove the negative,” she says. “Not everybody’s fertility is the same over time.” Which is why she worries that the difficulty of answering these questions in absolute terms can often generate concern on the part of patients.

Further complicating matters is the simple fact that, generally speaking, infertility is rising, particularly amongst men. “Most of us now know at least one person, if not multiple people, that have had that struggle,” says LoConte. “The data would reflect that that’s true, and it’s likely due to the fact that many of us are waiting until we’re older to start having children.” Not to mention that, as a population, “we’re heavier than we used to be,” which also adversely affects male fertility. 

To put some of these concerns around male fertility and the COVID vaccine to rest, a team of researchers at the University of Miami Miller School of Medicine have begun a clinical trial to determine if the vaccine is harmful to men’s sperm. “We created the study because this is a novel vaccine that hasn’t undergone the typical rigorous animal testing (in which fertility impact is evaluated) given the severity of the pandemic,” says Ranjith Ramasamy, a reproductive urologist at the University of Miami. 

According to a representative from the FDA, “There is no scientific evidence to suggest that COVID-19 vaccines can cause infertility.” They add, however, that while an evaluation of fertility may “be included as a component of a developmental toxicity study submitted to FDA, it isn’t required.” Therefore, since both COVID vaccines are authorized under an Emergency Use Authorization, ongoing clinical trials like Ramasamy’s will continue, the same representative tells me, “in order to obtain additional safety information intended to support eventual approval.”

To effectively rule out any concerns with the COVID vaccine as it relates to sperm quality, Ramasamy and his team are analyzing the semen of 60 men, ages 18 to 50, prior to receiving a COVID-19 vaccine and then again at three and six months afterward. “[We’re] looking for any changes in the sperm concentration and sperm motility,” he says. 

Ramasamy tells me that since previous studies have demonstrated that the virus can be present within the testes, and that the COVID-19 infection can decrease sperm production, they wanted to design “this study to reassure the public that vaccination will not affect fertility in case this was extrapolated.”

LoConte is quite familiar with these sorts of extrapolations. In 2020, she and a team of researchers set out to disprove an article that was making its rounds on an anti-vax website called Age of Autism. The article, she says, suggested that the HPV vaccine was linked to infertility in women. “We just sat down and said, ‘We could do nothing,’” LoConte recalls. “‘We could write a letter to the editor, which would take forever to publish. We could put ourselves out on Twitter and get completely destroyed by the anti-vax people. Or, as fun as that is, we could sit down and do the analysis correctly.’” 

The author of the article posted on the Age of Autism website, it turned out, was using the wrong variables. “She [the author of the article] looked at the question of, ‘Have you been pregnant?’ which isn’t the right question when you’re asking about fertility,” says LoConte. “The right question is, ‘Have you been pregnant, and were you trying to get pregnant?’ Because if you haven’t been pregnant, but you were taking your birth control pills, or your partner was using a condom, that’s great. That’s a win. That’s not a sign of a problem.”

Based on her own analysis, LoConte found that not only did the HPV vaccine not hurt fertility, it actually helped it, “probably because acute HPV infection decreases sperm motility,” says LoConte. “So if the female has HPV, and she gives it to the male partner, his sperm isn’t as fertile.”

Similarly, Ramasamy doesn’t expect to find any issues with regard to male fertility and the COVID vaccine. “The main concern is that if young men fear the vaccine for whatever reason, the pandemic will continue,” he says. “Additionally, moderate or severe COVID-19 infection is most likely a greater risk to infertility than the vaccine itself.”

Ramasamy’s concerns are well directed. Per Bo Harstine, an expert in male reproductive biology and sperm health, researchers are learning that COVID-19 can definitely “be detected within — and have negative effects — on the testes and sperm production.” In other words, far more concerning for most physicians are the potential lingering effects that a COVID-19 infection could have on male fertility. “This isn’t surprising, since it’s well understood how other viral infections, such as Mumps or Hepatitis, can negatively impact male reproductive health,” says Harstine. “The implications of fertility during a COVID-19 illness are real because of what’s happening in the testicles.” 

But not only is inflammation and fever negatively affecting sperm production in several ways, according to Harstine, it’s also been shown that the COVID-19 virus can “bind to receptors of cells within the testes, which are needed to facilitate spermatogenesis, and this receptor binding alters gene expression that impacts sperm production.” Worse still is the fact that inflammation-related processes are detectable within the testes of patients who have died of COVID-19, Harstine explains, “to the extent that their sperm production was severely compromised or even wiped out completely.”

This, Harstine adds, is hardly surprising, considering that the testes are also hugely important because of their endocrine functions (meaning that they’re the main site of testosterone and other hormone production). “Imbalances to hormone production have consequences that go beyond compromised sperm production,” says Harstine. For example, inflammation and fever, two common symptoms of COVID-19, can work in tandem to negatively affect sperm production. “The testes are especially sensitive to increased temperatures; consider that the purpose of the scrotum is to house the testes outside the body cavity to ensure they remain at a lower temperature than the body, and this is necessary for proper sperm production,” Harstine explains. 

In the best-case scenario — i.e., one with no permanent damage to the vascular, cellular or molecular aspects of the testes — the process of sperm cell development would be expected to reinitiate properly following a COVID-19 infection, and healthy sperm would be expected in a few months’ time. “The length of time for spermatogenesis, or the time it takes a sperm cell to mature within the testes, is around 74 days in humans,” says Harstine. “Therefore, patients whose sperm quality was affected during COVID-19 illness would hope that viable sperm would be present in two-and-a-half to three months after symptoms were gone.”

It will be at least a few more months before Ramasamy expects to have any publishable data from his clinical trials. If he were to find any link between male infertility and the vaccine, he tells me that it would be “inhumane to withhold the information and not make it public,” despite the implications it might have on the vaccine’s rollout. 

Nonetheless, clinical trials like Ramasamy’s and LoConte’s — both undertaken not because of any legitimate scientific concerns, but to assuage public fear around vaccines — are sure to continue. “I’d imagine we’re going to have to do more of this, which is to say, people don’t really trust, on face value, the opinion of scientists,” says LoConte. “You need to prove it to them.” 

Still, LoConte doesn’t think this is necessarily a bad thing, even if it does occasionally direct the science in a way that might be less productive. “The anti-vax movement has made vaccines the bogeyman, and it’s an easy thing to blame because many people don’t understand immunology and don’t understand how it works,” says LoConte. “But when you sit down and think, ‘Could vaccines really cause autism?’ You don’t need an MD to be like, ‘That doesn’t really make sense. That doesn’t scientifically make sense.’” 

Ironically, though, it was a physician who helped propagate these ideas in the first place, granting this particular brand of conspiracy with credence. And with it came a movement that today stands at more than 31 million people on Facebook. “And now,” LoConte says, “these people don’t just believe that vaccines cause autism — which they don’t, of course. They believe that vaccines cause everything.”