Does the Pfizer COVID Vaccine Reduce Sperm Quality?

Concerns about COVID vaccines affecting fertility have surfaced several times during the pandemic.

A lot of research has been done to reassure people that vaccines have no effect on fertility or pregnancy in women.

There have also been studies into whether vaccines affect sperm quality in men, one of which has recently been shared widely online.

A stock image shows sperm cells. There have been many studies into COVID vaccines and fertility.
Cypro / Getty


On June 17, a study was published in the magazine andrology Title ‘COVID-19 vaccination BNT162b2 temporarily reduces semen concentration and total motility among semen donors’.

study was shared reddit, where it gained over 17,000 upvotes and nearly 1,500 comments within three days. Some users expressed concern about the results of the study, which showed a temporary drop in sperm count after vaccination.


As its title suggests, the June 17 study did indeed show that a drop in sperm concentration occurred a few months after vaccination in a small group of men who volunteered.

Specifically, the study examined 220 sperm samples from 37 men who had received two doses of the Pfizer COVID vaccine. Sperm samples were obtained several times – once before vaccination (T0), once 15 to 45 days after vaccination (T1), once 75 to 150 days after vaccination (T2), and once 150 to 150 days after vaccination. Days later (T3).

In each sample, the researchers examined factors such as semen volume, sperm concentration, sperm motility and total motility.

There was no significant change between T0 and T1, but sperm concentrations were found to be approximately 15.4 percent lower than T2 and 22.1 percent lower in total motility. Volume and mobility were not changed significantly. By T3, it looked like the cut had healed.

The authors stressed that, rather than concerning, their results “confirm previous reports about the overall safety and reliability of vaccines despite minor short-term side effects.”

The study reads: “Since misinformation about health-related topics represents a public health threat, our findings should support vaccination programs.”

However, despite the clear findings, the study is not conclusive. Dr. Ranjit Ramasamy, director of reproductive urology at the University of Miami Health System newsweek that they considered the changes observed in the study to be within a normal range.

“Even though the numbers may be statistically significant, I don’t think they achieve clinical significance,” he said. “Maybe men who mount a greater immune response to the vaccine may have an adverse but temporary effect, but larger studies are needed to definitively answer this question.”

Amelia Weselink, MD, research assistant professor of epidemiology at the Boston University School of Public Health who has conducted studies in COVID vaccination and fertility, explained newsweek It was nice that the study collected multiple semen samples before and after vaccination, but highlights its small sample size.

They also noted that the authors did not say whether they accounted for other factors that could affect semen characteristics, such as stress or seasonal changes. Even COVID itself can affect sperm quality.

“We’ve known for a long time that fever can impair sperm development and function,” she said. “So it’s certainly possible that if fever is a side effect of vaccination, there could be damage to sperm quality over the next few months. But the same is true for other things that cause fever—including COVID infection. And for COVID infection, there is evidence that damage to sperm can last longer than several months. So overall, these results, if there are causes, are not particularly concerning.”

It also isn’t the only study examining vaccines and sperm quality. a studydue to be published in International Journal of Gynecology and Obstetrics The following month and published online in February, suggested that the vaccines had no ill effects on sperm quality, based on 898 samples from 33 men. These men’s sperm samples were tested once before their second Pfizer vaccine shot and again at least 72 days later.

In fact, that study even suggested that total sperm count and total motility increased after the second vaccine compared to before vaccination.

Study June 1, 2021 published In The Journal of the American Medical Association which included 45 men, reached a similar conclusion, showing that “no significant reduction in any sperm parameter occurred” before and after two doses of either Pfizer or Moderna vaccines, and also appeared to show an increase Gave. The authors suggested that this increase was “within normal individual variation and may have been affected by regression to the mean.”


Fact Check - Mostly Wrong

Mostly false.

One study did indeed show that the second vaccine dose coincided with a temporary drop in sperm count that later recovered, but this is not a conclusive study and several earlier studies showed the opposite to be true. More research is needed on this topic.

Fact Check by Greeley Tribune

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