Research Rebuts Claims Linking COVID-19 Vaccines to Male Infertility

SciCheck Digest

A new study found there was no negative effect on sperm levels in men after receiving the COVID-19 vaccines, undercutting suggestions that the shots affect male fertility. But social media posts have made the baseless claim that vaccinated men “are effectively sterile.”

More than half a billion doses of COVID-19 vaccines have now been administered in the U.S. and only a few, very rare, safety concerns have emerged. The vast majority of people experience only minor, temporary side effects such as pain at the injection site, fatigue, headache, or muscle pain — or no side effects at all. As the Centers for Disease Control and Prevention has said, these vaccines “have undergone and will continue to undergo the most intensive safety monitoring in U.S. history.”

A small number of severe allergic reactions known as anaphylaxis, which are expected with any vaccine, have occurred with the authorized and approved COVID-19 vaccines. Fortunately, these reactions are rare, typically occur within minutes of inoculation and can be treated. Approximately 5 per million people vaccinated have experienced anaphylaxis after a COVID-19 vaccine, according to the CDC.

To make sure serious allergic reactions can be identified and treated, all people receiving a vaccine should be observed for 15 minutes after getting a shot, and anyone who has experienced anaphylaxis or had any kind of immediate allergic reaction to any vaccine or injection in the past should be monitored for a half hour. People who have had a serious allergic reaction to a previous dose or one of the vaccine ingredients should not be immunized. Also, those who shouldn’t receive one type of COVID-19 vaccine should be monitored for 30 minutes after receiving a different type of vaccine.

There is evidence that the Pfizer/BioNTech and Moderna mRNA vaccines may rarely cause inflammation of the heart muscle (myocarditis) or of the surrounding lining (pericarditis), particularly in male adolescents and young adults.

Based on data collected through August 2021, the reporting rates of either condition in the U.S. are highest in males 16 to 17 years old after the second dose (105.9 cases per million doses of the Pfizer/BioNTech vaccine), followed by 12- to 15-year-old males (70.7 cases per million). The rate for 18- to 24-year-old males was 52.4 cases and 56.3 cases per million doses of Pfizer/BioNTech and Moderna vaccines, respectively.

Health officials have emphasized that vaccine-related myocarditis and pericarditis cases are rare and the benefits of vaccination still outweigh the risks. Early evidence suggests these myocarditis cases are less severe than typical ones. The CDC has also noted that most patients who were treated “responded well to medicine and rest and felt better quickly.”

The Johnson & Johnson vaccine has been linked to an increased risk of rare blood clots combined with low levels of blood platelets, especially in women ages 30 to 49. Early symptoms of the condition, which is known as thrombosis with thrombocytopenia syndrome, or TTS, can appear as late as three weeks after vaccination and include severe or persistent headaches or blurred vision, leg swelling, and easy bruising or tiny blood spots under the skin outside of the injection site.

According to the CDC, TTS has occurred in around 4 people per million doses administered. As of early April, the syndrome has been confirmed in 60 cases, including nine deaths, after more than 18.6 million doses of the J&J vaccine. Although TTS remains rare, because of the availability of mRNA vaccines, which are not associated with this serious side effect, the FDA on May 5 limited authorized use of the J&J vaccine to adults who either couldn’t get one of the other authorized or approved COVID-19 vaccines because of medical or access reasons, or only wanted a J&J vaccine for protection against the disease. Several months earlier, on Dec. 16, 2021, the CDC had recommended the Pfizer/BioNTech and Moderna shots over J&J’s.

The J&J vaccine has also been linked to an increased risk of Guillain-Barré Syndrome, a rare disorder in which the immune system attacks nerve cells. Most people who develop GBS fully recover, although some have permanent nerve damage and the condition can be fatal.

Safety surveillance data suggest that compared with the mRNA vaccines, which have not been linked to GBS, the J&J vaccine is associated with 15.5 additional GBS cases per million doses of vaccine in the three weeks following vaccination. Most reported cases following J&J vaccination have occurred in men 50 years old and older.

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Early in the rollout of COVID-19 vaccines in the U.S., we addressed questions and claims about the impact of vaccination on fertility. Some claims used a bogus argument to conclude that the mRNA vaccines — from Pfizer/BioNTech and Moderna — would cause “female sterilization.” In reality, the Centers for Disease Control and Prevention notes that there is no evidence any vaccine, including those for COVID-19, cause fertility problems.

More recently, some posts swirling on social media have spread an unfounded narrative that the vaccines will create widespread infertility problems for men.

A May 23 story published on a website called the Daily Expose, based in the U.K., and shared on Facebook more than 1,100 times, claims that the “VACCINES could cause ‘mass male infertility.'”

The story cites an interview with Roger Hodkinson — a Canadian pathologist who in 2020 reportedly called COVID-19 “the biggest hoax,” erroneously likening the disease to the flu. It claims that “the spike protein expresses in the placenta and the testes,” which “could kill unborn babies in current pregnancies and permanently stop men having children.” The Daily Expose story also takes aim at Dr. Anthony Fauci, suggesting the director of the National Institute of Allergy and Infectious Diseases is a “dead man walking.”

The claims have been republished on other websites and spread elsewhere, including on Twitter and Instagram — where one popular post declared that “all males who have been vaccinated are effectively sterile.”

But experts say there is no evidence that the vaccines cause infertility in men. And there are new data that further undercut the online claims.

In a study published June 17 in the Journal of the American Medical Association, researchers at the University of Miami reported that they found “no significant decreases in any sperm parameter” among a group of healthy men before and after receipt of a COVID-19 vaccine. The team collected semen samples of 45 men, 18 and older, before receiving either the Pfizer/BioNTech or Moderna vaccine — and again more than 70 days after receiving their second dose.

“This is the full life cycle of sperm and 70 days is sufficient time to see if the vaccine impacts semen parameters,” Daniel C. Gonzalez, a medical student at the university and one of the study’s authors, said in a statement. “We measured semen volume, sperm concentration, and the total amount of moving sperm and found there were no declines in any of the parameters as compared to the baseline analysis.”

Researchers at a hospital in Israel have reported similar findings in a study that has not yet been peer-reviewed. That study evaluated the sperm production in 43 men before and after receiving the Pfizer/BioNTech vaccine. “Our results demonstrate that the vaccine does not impair sperm parameters,” the authors wrote.

*Photo by Yulia Reznikov via Getty Images*

Dr. Puneet Masson, director of male reproductive medicine and surgery at Penn Medicine, also told us in a phone interview that his observations in the field rebut the notion that vaccines are detrimental to male fertility.

“I’ve had patients who had fertility testing pre-vaccine and post-vaccine, just by virtue of my practice, and I have not had any patients I can think of who have had any adverse reactions from the vaccines in terms of fertility,” he said.

The Society for Male Reproduction and Urology and the Society for the Study of Male Reproduction issued a joint statement in January saying that “COVID-19 vaccines should be offered to men desiring fertility, similar to men not desiring fertility, when they meet criteria for vaccination.”

The statement notes that some men could experience a fever following vaccination, which “can cause temporary declines in sperm production.”

“Thus, if a man experiences fever as the result of the COVID-19 vaccine, he may experience a temporary decline in sperm production, but that would be similar to or less than if the individual experienced fever from developing COVID-19 or for other reasons,” the statement said.

Masson said that “someone getting a mild fever from a vaccine is still better” than getting COVID-19, especially since a fever from the disease may last longer.

Experts say a fever could affect a man’s fertility for upward of three months. But again, that’s any fever — not something unique to a fever following vaccination.

Hodkinson — the Canadian pathologist cited in the Daily Expose story alleging the potential for “mass male infertility” — made similar suggestions in a May video interview. He claimed that the ACE2 receptor “is present in the testes” and “it’s actually on the cells that produce spermatozoa.” On the screen of the video, the headline of a paper reads: “ACE2 receptor expression in testes: implications in coronavirus disease 2019 pathogenesis.”

That paper was published in 2020 in the journal Biology of Reproduction. The study dealt with the COVID-19 disease, not the vaccines.

Two of the study’s authors told us in an email that there was “[a]bsolutely not” anything in their paper that suggests the vaccines could cause issues with the testes or male fertility.

The paper “is a hypothetical article about the potential effect of SARS-CoV-2 infection on male reproductive health, not about the impact of COVID-19 vaccine on male reproductive health,” said Saguna Verma, a professor and immunologist at the University of Hawaii, and Dr. Hooman Sadri, an assistant professor and reproductive biologist at Wake Forest University.

“We hypothesized that SARS-CoV-2 could infect testes cells and lead to testosterone reduction or germ cell depletion for short-term period. This hypothesis was based on the clinical reports of reduced testosterone levels in COVID-19 patients,” they said. They noted that “these effects were transient in patients,” so their paper did not prove that infection with the virus leads to male infertility, either.

On that point, the University of Miami research team that studied male fertility and the COVID-19 vaccines has previously reported evidence that three men who died from COVID-19 had impaired sperm function — and that the virus was present in the testes of one man — prompting questions about whether the virus itself could potentially affect male fertility. The study’s lead author, Dr. Ranjith Ramasamy, suggested further studies on the issue are in order.

Correction, June 18: Saguna Verma is a professor, not an associate professor, at the University of Hawaii. We have corrected the story.

Editor’s note: SciCheck’s COVID-19/Vaccination Project is made possible by a grant from the Robert Wood Johnson Foundation. The foundation has no control over our editorial decisions, and the views expressed in our articles do not necessarily reflect the views of the foundation. The goal of the project is to increase exposure to accurate information about COVID-19 and vaccines, while decreasing the impact of misinformation.

Sources

Achua, Justin K., et al. “Histopathology and Ultrastructural Findings of Fatal COVID-19 Infections on Testis.” World Journal of Men’s Health. 3 Nov 2020.

Gonzalez, Daniel C., et al. “Sperm Parameters Before and After COVID-19 mRNA Vaccination.” Journal of the American Medical Association. 17 Jun 2021.

Hilton, Lisette. “COVID-19 Can Infect Testes with Potential Implications for Male Fertility.” Press release, University of Miami Health System. 5 Nov 2020.

Jaramillo, Catalina. “No Evidence Vaccines Impact Fertility.” FactCheck.org. Updated 3 Mar 2021.

“Joint Statement Regarding COVID-19 Vaccine in Men Desiring Fertility from the Society for Male Reproduction and Urology (SMRU) and the Society for the Study of Male Reproduction (SSMR).” Press release, American Society for Reproductive Medicine. 9 Jan 2021.

Masson, Puneet. Director of male reproductive medicine and surgery, Penn Medicine. Phone interview with FactCheck.org. 10 Jun 2021.

“Myths and Facts about COVID-19 Vaccines.” Centers for Disease Control and Prevention. 3 Jun 2021.

Verma, Saguna. Professor, University of Hawaii. Email to FactCheck.org. 16 Jun 2021.

Villalpando, Nicole. “Could COVID-19 vaccine cause male infertility? The answer is nuanced.” Austin American-Statesman. 17 May 2021.

Watson, Rachel E., et al. “Fertility considerations: The COVID-19 disease may have a more negative impact than the COVID-19 vaccine, especially among men.” Fertility and Sterility. 19 Mar 2021.