Sexual transmission of COVID-19 is unlikely, according to a new international study published in Fertility & Sterility. Researchers found no evidence of the virus in the semen of patients recovering from COVID-19 1 month after diagnosis and no expression of an enzyme and protease that may be linked to entry of SARS-CoV-2 into cells in the testicles. They noted, however, that the long-term effects of SARS-CoV-2 on male reproductive function remain unknown.
The participants in the study were 34 males, aged 18 to 57, who had been diagnosed with COVID-19 in Wuhan, China, between January 26, 2020 and March 2, 2020. The median age of the sample was 37 years. Semen samples and expression patterns of angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in different cells of the testes were evaluated. ACE2 likely mediates viral entry of SARS-CoV-2 into target cells; TMPRSS2 may enhance that entry and has been found in prostatic epithelial cells.
Presence of SARS-CoV-2 in a single ejaculated semen sample from each participant was evaluated using quantitative reverse transcription polymerase chain reaction. A dataset from the University of Utah was used to evaluate expression of ACE2 and TMPRSS2 in testicular cells.
Six of the patients (19%) from whom the semen samples were taken had scrotal discomfort concerning for vital orchitis around the time of COVID-19 confirmation. After a median of 31 days, COVID-19 was not detected in the samples. Single-cell transcriptome analysis showed sparse expression of ACE2 and TMPRSS2, with almost no overlapping gene expression.
The researchers underscored that they were only able to obtain one semen sample per participant for this study, and only three patients provided their sample within 14 days of being diagnosed with COVID-19. “This limits our ability to provide data on possible early viral shedding in the semen,” they wrote. Understanding the long-term impact of SARS-CoV-2 on male reproductive function, including fertility and testicular endocrine function, the authors said, requires further research.