The current coronavirus pandemic has created a new reality. Eventually, we will get back to our lives, albeit very much aware of the invisible pathogens around us. My last blog discussed the possible presence of SARS-CoV-2 in the testis (NYCryo.com/blog). What about SARS-CoV-2 in semen? What about our future reproductive capabilities? Will there be a lasting effect of this novel virus? The simple answer is that we don’t know, and much work will be needed to determine the long-term impact on our fertility. I will present what we know about viruses in semen and their infectivity and potential impact on the partner and offspring.
The Society for Assisted Reproductive Technologies (SART) has recommended during this pandemic to stop new assisted reproductive procedures except for urgent cryopreservation (1). Good advice in light of the morbidity and potential mortality of this disease, as well as the poorly defined modality of transmission. There is always the possibility of contamination in semen specimens stored in liquid nitrogen. However, viruses can result in poor quality sperm but not thought to be transmitted to the partner or offspring (2).
This leads to the two questions: What do we know about the presence of this virus in gametes and embryos and the potential for sexual transmission of the virus? Will the use of semen from infected individuals result in infection of the female recipient or offspring?
Can SARS-COV-2 be transmitted through sex? This seemingly simple question is more complicated to answer than it seems. An editorial by Feldmann in the New England Journal of Medicine addressed this issue in 2018 (3). Dr. Feldmann made a point of differentiating between the presence of a virus detected in a semen sample and the infectivity of that virus. Many viruses are found in semen. However, they are not infectious. A measurement of infectivity is needed. To measure infectivity, you need to know the amount of virus required to cause an infection as well as the pathway that results in infection. For example, if a pathogen such as a virus is in semen but needs to be aerosolized and inhaled to become infectious, then it is less likely to be transmitted to another person. However, other pathogens such as Zika and Ebola can be transmitted by semen to another person through sexual contact. It appears, from the limited information available, that SARS-COV-2 is transmitted through transfer into the lungs by the act of breathing in aerosolized particles containing the virus or transfer of the virus from a surface containing the virus to a person’s mouth or nose even from COVID-19 positive individuals without symptoms (4). Hence, the requirement for hand-hygiene and social distancing. However, it is unlikely that sex, even if the virus is in semen, would be a significant modality of transmission.
What do we know about the presence of SARS-CoV-2 in semen? There is only one small, non-peer reviewed study of 13 patients that I found online (5). In this study, all patients were confirmed positive by nasopharyngeal swab testing for real-time reverse transcription polymerase chain reaction (rRT-PCR) for SARS-CoV-2. They followed these patients with both repeat rRT-PCR testing as well as serology of blood for both IgM and IgG antibodies. They also tested semen (12 patients) and testicular biopsy specimen (1 patient) for SARS-CoV-2 RNA by rRT-PCR. None of the semen specimens or the testicular biopsy specimen was found to be positive for SARS-CoV-2. Several cautions should be noted in interpreting the results of this study besides the low number of patients. First, the methodology for testing semen and testicular biopsies has not been validated. Second, only one patient’s semen and one patient’s testis tissue was tested when the rRT-PCR was still positive.
If SARS-COV-2 is present in semen will it adversely affect the embryo, fetus, or child? Toga in insight into this question, one needs to look at the animal literature, in particular bovine and equine research. Viruses can attach to, and sometimes be integrated into spermatozoa (6). In turn, this can theoretically result in embryos with the virus. As reported by these authors, ‘It has never been demonstrated that infected embryos have resulted in infection of the recipients or offspring.’ Several viruses that are found in human semen (eg Mumps, HIV, Zika, Influenza, Coxsackie) are known to cause orchitis in susceptible men (7). Orchitis can result in impaired testicular function and sperm production but not the transmission of the virus to a partner or offspring. However, a few (eg HIV, Zika) appear to be sexually transmitted to the partner and at least one (eg Zika) is known to affect the developing fetus.
Closing thoughts: Viruses can be found in semen; they can survive the freeze/thaw process of cryopreservation and potentially can be transmitted to the partner and offspring. However, there is currently no data suggesting that SARS-CoV-2 can be transmitted to the partner and offspring from either fresh or cryopreserved semen. My recommendation follows the SART recommendation that urgent cryopreservation should continue for men requiring urgent gonadotoxic therapy. Patients should be made aware of the limited data available, and that the specimens should be quarantined until high-quality evidence is available.
#covid19 #infertility #semen #coronavirus
- Wiwanitkit,J, Semen banking: consideration on viral contamination in the era of new emerging viral infection, Iranian Journal of Reproductive Medicine, 9(2):145-146, 2011
- Feldmann,H, Virus in Semen and the Risk of Sexual Transmission, New Engl J Medicine, 378;15, 2018
- Song, C., Wang, Y., Li, W., Hu, B., Chen, G., Xia, P., Wang, W., Li, C., Sha, J., hu, z., Yang, X., Yao, B., Liu, Y. (2020). Detection of 2019 novel coronavirus in semen and testicular biopsy specimen of COVID-19 patients medRxiv https://dx.doi.org/10.1101/2020.03.31.20042333
- Wrathall, A., Simmons, H., Soom, A. (2006). Evaluation of risks of viral transmission to recipients of bovine embryos arising from fertilisation with virus-infected semen Theriogenology 65(2), 247-274. https://dx.doi.org/10.1016/j.theriogenology.2005.05.043
- Liu, W., Han, R., Wu, H., Han, D. (2018). Viral threat to male fertility. Andrologia 50(11), e13140. https://dx.doi.org/10.1111/and.13140