Sexual Transmission Of COVID-19 Is Unlikely, Study Suggests

A new study found that the chances of COVID-19 spreading through semen were "remote." That said, intimate physical contact can still increase the likelihood of spreading the disease.

An international team of researchers from China and the United States investigated whether the virus that causes COVID-19, SARS-CoV-2, can be sexually transmitted just like Zika and Ebola. For the study, the researchers collected semen samples from 34 Chinese men between 29 and 36 days after they were diagnosed with COVID-19, and the laboratory tests did not detect the virus in any of the samples.

However, all of the participants in the study only developed a mild or moderate illness. None of them had severe COVID-19. As such, the researchers noted it was still possible that those who develop a more severe case of COVID-19 have a higher load of the virus and therefore could have a bigger chance of their semen being affected.

"We just don't have the answer to that right now," study co-author James M. Hotaling, M.D. said. "But knowing that we didn't find that kind of activity among the patients in this study who were recovering from mild to moderate forms of the disease is reassuring."

The researchers further investigated whether the virus affected the testes, since the absence of the virus in the semen does not automatically mean that it has not affected the testes.

"If the virus is in the testes but not the sperm it can't be sexually transmitted," study co-author Jingtao Guo, Ph.D., of the Huntsman Cancer Institute at the University of Utah said. "But if it is in the testes, it can cause long-term damage to semen and sperm production."

To find out, the researchers investigated the two genes that allowed SARS-CoV-2 to penetrate cells and replicate, ACE2 and TMPRSS2. For the virus to successfully invade the cells, both have to be present in the same cell.

Out of 6,500 testicular cells the researchers examined, only four had the genes that encoded the two proteins, suggesting the virus was "unlikely" to invade human testicular cells.

"ACE2-mediated viral entry of SARS-CoV-2 into target host cells is unlikely to occur within the human testicle based on ACE2 and TMPRSS2 expression," the researchers wrote.

"The fact that in this small, preliminary study that it appears the virus that causes COVID-19 doesn't show up in the testes or semen could be an important finding," Hotaling said. "If a disease like COVID-19 were sexually transmittable that would have major implications for disease prevention and could have serious consequences for a man's long-term reproductive health."

Although the study was not quite comprehensive enough to completely rule out the possibility of sexual transmission because the sample size was rather small, overall, its findings suggested the chances of COVID-19 being sexually transmitted were remote.

However, the authors noted intimate contact such as kissing can also increase the risk of transmitting COVID-19, especially since asymptomatic people can also pass the virus to others.

The study was published in Fertility & Sterility.