In a recent study published in the journal PLOS ONE, researchers conducted a systematic review and meta-analyzed data on the impact of coronavirus disease 2019 (COVID-19) on male reproductive hormones and semen variables to determine whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections had an adverse impact on male fertility.
Background
The etiological agent of the COVID-19 pandemic, SARS-CoV-2, is a β-coronavirus that infects human cells by binding to the angiotensin-converting enzyme-2 (ACE-2) receptor. The ACE-2 receptor is found in the lungs, kidneys, heart, and testes, making all these organs possible entry points for the virus.
The COVID-19 pandemic was responsible for over 700 million cases and more than 7 million deaths. However, although the virus is known to primarily infect the respiratory system, research indicates that it can also adversely impact other organ systems. Studies have also found that SARS-CoV-2 infections are more severe in males than in females. Furthermore, studies have found that many males who had been infected with the earlier SARS-CoV-1 had developed orchitis or inflammation of the testes.
However, the data on the impact of SARS-CoV-2 on male reproductive health has been limited. Although some studies have reported associations between COVID-19 and decreased testosterone levels and lower semen quality, some of the findings have been considered methodologically weak.
About the study
The present study aimed to comprehensively review recent studies examining the impact of COVID-19 on male fertility and conducted a meta-analysis by comparing semen quality variables and reproductive hormone levels between infected and uninfected men to understand the influence of SARS-CoV-2 on male fertility.
The researchers used the PECO, or Population, Exposure, Comparator, and Outcomes, model to select studies that examined male patients of reproductive age who had been exposed to SARS-CoV-2. The review included both prospective and retrospective studies as long as they included COVID-19-negative controls or contained pre- and post-COVID-19 pandemic health data for the same individual. Studies that were in vitro, focused on female patients, or lacking control groups were excluded.
For the studies included in the review, the outcomes consisted of measurements of conventional semen parameters such as sperm count, ejaculate volume, sperm concentration, morphology, motility, and viability of the sperm, as well as leukocyte levels in the seminal fluid. The outcomes also included the levels of the male reproductive hormones, including testosterone, estrogen, prolactin, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). The Measurements also included ratios of testosterone to LH and FSH to LH.
For the meta-analysis, the data extracted from the studies consisted of sample sizes, country of study, study design, the methods used to diagnose COVID-19, and key outcomes. The researchers used this data to calculate standardized mean differences, with extensive sensitivity analyses to avoid bias and assess sources of diversity. The parameters were also compared for changes before and after treatment for COVID-19.
Results
The review identified 40 eligible studies published from 12 different countries between 2020 and 2023 that examined the impact of SARS-CoV-2 on male reproductive health. The key findings from the meta-analysis covered the impact of COVID-19 on several aspects of male reproductive health.
The study found that COVID-19 was significantly associated with decreased ejaculate volume, with sensitivity analyses confirming consistent reductions in ejaculate volume after SARS-CoV-2 infections. However, the sensitivity analyses showed that the difference in ejaculate volume before and after COVID-19 treatment was not statistically significant, indicating that the impact of treatment may be limited. The sperm counts also decreased after SARS-CoV-2 infections, although the sensitivity analyses indicated that these reductions were marginal.
Individuals infected with SARS-CoV-2 also showed significantly lower sperm concentrations, and no changes were seen in sperm concentrations after treatment for COVID-19. This finding remained consistent even after accounting for potential study biases and diversity, reinforcing the robustness of the result. COVID-19 was also found to lower sperm viability and motility, with the difference in sperm viability remaining consistent even after the sensitivity analysis.
Comparisons between infected and uninfected individuals revealed no significant differences in sperm morphology. However, comparisons of sperm morphology in the same individual before and after SARS-CoV-2 infections revealed lower levels of morphologically normal sperm. The analysis showed that while the overall morphology differences between infected and uninfected individuals were not significant, the within-individual changes suggest that SARS-CoV-2 may have a subtle but noteworthy effect on sperm morphology.
The reproductive hormone levels were also significantly altered in COVID-19 patients, with elevated prolactin and marginally higher estrogen levels in infected men. Interestingly, the study found substantial variability in testosterone levels before and after treatment, suggesting that COVID-19’s impact on this hormone may be more complex than initially understood. However, the leukocyte levels in the seminal fluid were similar between infected and uninfected men.
Conclusions
To summarize, the study reviewed and conducted a meta-analysis of studies examining the impact of COVID-19 on male reproductive health and found that SARS-CoV-2 had a significant negative impact on male fertility, particularly on parameters such as ejaculate volume, viability, and motility of the sperm, and sperm concentration and count. Although the treatment of COVID-19 partially alleviated some of the affected parameters, the findings suggest that these improvements may not be sufficient to restore pre-infection levels, particularly for parameters like sperm concentration and motility. The study also highlighted the need for further research to fully understand the long-term effects of COVID-19 on male fertility and to explore potential therapeutic interventions.
- V. J., Ashonibare, P. J., Ashonibare, T. M., Akhigbe, & E, A. R. (2024). SARS-CoV-2 impairs male fertility by targeting semen quality and testosterone level: A systematic review and meta-analysis. PLOS ONE, 19(9), e0307396-. DOI:10.1371/journal.pone.0307396, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0307396
News
Study Shows Brain Signals Only Matter if They Arrive on Time
Signals are processed only if they reach the brain during brief receptive cycles. This timing mechanism explains how attention filters information and may inform therapies and brain-inspired technologies. It has long been recognized that [...]
Does Space-Time Really Exist?
Is time something that flows — or just an illusion? Exploring space-time as either a fixed “block universe” or a dynamic fabric reveals deeper mysteries about existence, change, and the very nature of reality. [...]
Unlocking hidden soil microbes for new antibiotics
Most bacteria cannot be cultured in the lab-and that's been bad news for medicine. Many of our frontline antibiotics originated from microbes, yet as antibiotic resistance spreads and drug pipelines run dry, the soil [...]
By working together, cells can extend their senses beyond their direct environment
The story of the princess and the pea evokes an image of a highly sensitive young royal woman so refined, she can sense a pea under a stack of mattresses. When it comes to [...]
Overworked Brain Cells May Hold the Key to Parkinson’s
Scientists at Gladstone Institutes uncovered a surprising reason why dopamine-producing neurons, crucial for smooth body movements, die in Parkinson’s disease. In mice, when these neurons were kept overactive for weeks, they began to falter, [...]
Old tires find new life: Rubber particles strengthen superhydrophobic coatings against corrosion
Development of highly robust superhydrophobic anti-corrosion coating using recycled tire rubber particles. Superhydrophobic materials offer a strategy for developing marine anti-corrosion materials due to their low solid-liquid contact area and low surface energy. However, [...]
This implant could soon allow you to read minds
Mind reading: Long a science fiction fantasy, today an increasingly concrete scientific goal. Researchers at Stanford University have succeeded in decoding internal language in real time thanks to a brain implant and artificial intelligence. [...]
A New Weapon Against Cancer: Cold Plasma Destroys Hidden Tumor Cells
Cold plasma penetrates deep into tumors and attacks cancer cells. Short-lived molecules were identified as key drivers. Scientists at the Leibniz Institute for Plasma Science and Technology (INP), working with colleagues from Greifswald University Hospital and [...]
This Common Sleep Aid May Also Protect Your Brain From Alzheimer’s
Lemborexant and similar sleep medications show potential for treating tau-related disorders, including Alzheimer’s disease. New research from Washington University School of Medicine in St. Louis shows that a commonly used sleep medication can restore normal sleep patterns and [...]
Sugar-Coated Nanoparticles Boost Cancer Drug Efficacy
A team of researchers at the University of Mississippi has discovered that coating cancer treatment carrying nanoparticles in a sugar-like material increases their treatment efficacy. They reported their findings in Advanced Healthcare Materials. Over a tenth of breast [...]
Nanoparticle-Based Vaccine Shows Promise in Fighting Cancer
In a study published in OncoImmunology, researchers from the German Cancer Research Center and Heidelberg University have created a therapeutic vaccine that mobilizes the immune system to target cancer cells. The researchers demonstrated that virus peptides combined [...]
Quantitative imaging method reveals how cells rapidly sort and transport lipids
Lipids are difficult to detect with light microscopy. Using a new chemical labeling strategy, a Dresden-based team led by André Nadler at the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) and [...]
Ancient DNA reveals cause of world’s first recorded pandemic
Scientists have confirmed that the Justinian Plague, the world’s first recorded pandemic, was caused by Yersinia pestis, the same bacterium behind the Black Death. Dating back some 1,500 years and long described in historical texts but [...]
“AI Is Not Intelligent at All” – Expert Warns of Worldwide Threat to Human Dignity
Opaque AI systems risk undermining human rights and dignity. Global cooperation is needed to ensure protection. The rise of artificial intelligence (AI) has changed how people interact, but it also poses a global risk to human [...]
Nanomotors: Where Are They Now?
First introduced in 2004, nanomotors have steadily advanced from a scientific curiosity to a practical technology with wide-ranging applications. This article explores the key developments, recent innovations, and major uses of nanomotors today. A [...]
Study Finds 95% of Tested Beers Contain Toxic “Forever Chemicals”
Researchers found PFAS in 95% of tested beers, with the highest levels linked to contaminated local water sources. Per- and polyfluoroalkyl substances (PFAS), better known as forever chemicals, are gaining notoriety for their ability [...]
