The emergence of SARS-CoV-2, the virus responsible for COVID-19, immediately raised questions about potential routes of human transmission beyond the respiratory system. People wondered whether the virus could be passed through sexual activity, particularly via semen, a fluid known to transmit other viruses. Understanding transmissibility requires scientific investigation into the virus’s presence in various bodily fluids. This article reviews what the scientific literature has concluded regarding the detection of SARS-CoV-2 in semen and the risk of sexual transmission.
Is SARS-CoV-2 Found in Semen
Initial investigations focused on whether the genetic material of SARS-CoV-2, known as RNA, could be identified in the seminal fluid of infected men. The male reproductive system contains cells that express the ACE2 receptor, the primary doorway the virus uses to enter human cells. This suggests a plausible biological mechanism for the virus to reach and reside in the testes.
Early studies yielded mixed results regarding the presence of viral RNA in semen. Some research involving men in the acute phase of infection found viral RNA in a small percentage of samples, sometimes up to 27% of men tested during their illness. However, many other studies, often involving men recovering from mild infections, reported no detectable SARS-CoV-2 RNA in their semen samples.
The inconsistency in detection is likely due to differences in patient severity, the timing of sample collection, and the sensitivity of the testing methods used. For instance, patients with more moderate or severe COVID-19 symptoms showed a higher rate of viral RNA detection in their semen than those with milder cases. The presence of viral RNA indicates that the virus has entered the male genital tract, but it does not automatically mean the virus is capable of causing an infection.
Detection Versus Infectious Transmission Risk
The central question is whether the detected viral genetic material represents viable, infectious virus particles that can be sexually transmitted. Viral RNA is essentially a leftover blueprint of the virus, which can persist long after the virus has been neutralized by the immune system. Therefore, detecting RNA only confirms presence, not infectivity.
To determine the risk of sexual transmission, scientists must attempt to isolate and culture live, replicating SARS-CoV-2 from semen samples in a laboratory setting. The vast majority of studies that detected viral RNA in semen have failed to isolate any infectious virus. This lack of culturable virus suggests that, even when the virus enters the genital tract, it does not survive or replicate effectively enough to be a common vector for infection.
While epidemiological evidence does not support SARS-CoV-2 as a sexually transmitted infection, a few studies have raised concerns about viral persistence. One notable study suggested that infectious viral particles could be detected in the testes for several months in some patients who had recovered from moderate COVID-19. Despite this finding, the current consensus is that sexual transmission via semen remains a negligible route compared to the primary mode of spread.
Why Respiratory Transmission Remains the Primary Concern
The low risk of transmission via semen must be understood in the context of the virus’s main method of spread. SARS-CoV-2 is primarily transmitted through respiratory droplets and aerosols expelled when an infected person coughs, sneezes, sings, talks, or breathes. This is an airborne threat that travels through the air and enters the respiratory system of a nearby person.
Intimate activities involve close, face-to-face contact that dramatically increases the risk of respiratory exposure. During sex, partners are typically breathing heavily and in close proximity for an extended period, which creates an ideal scenario for the exchange of respiratory droplets and aerosols. The risk of transmission during intimacy is overwhelmingly driven by this close physical contact and the exchange of breath, not by the seminal fluid itself.
Even if semen were entirely free of the virus, being physically intimate with someone who has an active COVID-19 infection presents a high risk of exposure. The close distance and the shared air space mean that a person is inhaling a concentration of virus particles released from the partner’s mouth and nose. The proven efficiency of respiratory transmission outweighs the theoretical or rare risk posed by viral material in semen.
Public Health Recommendations for Intimacy During Infection
Because the risk during intimacy is predominantly respiratory, public health guidance focuses on minimizing close contact when one partner is infected. The safest course of action to prevent transmission is temporary abstinence from all forms of close physical and sexual contact. This includes avoiding kissing and any activity that involves face-to-face contact.
If partners choose to be intimate while one is infected, minimizing the time spent in close proximity and using barrier methods for the respiratory route are recommended. Wearing a face mask during sexual activity can help reduce the expulsion and inhalation of respiratory droplets and aerosols. It is wise to avoid sexual practices that involve exposure to infectious fluids like saliva, urine, or feces.
Health organizations advise showering both before and after sex and thoroughly washing hands to minimize contact with any contaminated surfaces or skin. The highest-risk activities are those that involve kissing and close face-to-face contact, making them the first to be avoided. Ultimately, the guidance is designed to mitigate the risk posed by respiratory transmission during the shared intimate experience.