Sexual transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2): A new possible route of infection?

To the Editor: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the coronavirus disease (COVID-19), first identified in Wuhan, China, in December 2019, and that has now actually spread worldwide. The human-to-human transmission routes hitherto recognized include direct transmission, through cough, sneeze, droplet inhalation, and contact transmission, comprising contact with oral, nasal, and eye mucous membranes.

To date, COVID-19 has not been reported to be sexually transmitted. However, a series of data raises the possibility that sexual intercourse could be an additional direct way of infection. This hypothesis mainly derives from the recent evidence of a likely fecal-oral transmission. The exact mechanisms by which SARS-CoV-2 interacts with the gastrointestinal tract is unknown. However, angiotensin-converting enzyme II (ACE2) seems to be used by the virus as a receptor to enter cells. ACE2 messenger RNA is highly expressed in the gastrointestinal system, and immunofluorescent data show that the ACE2 protein is abundantly present in the glandular cells of rectal epithelia. , In addition, SARS-CoV-2 RNA identification and intracellular staining of viral nucleocapsid protein in rectal epithelia demonstrated that the virus infects such epithelial cells.2, 3, 4

The recognition of viral RNA from feces indicates that virions are secreted from the virus-infected cells.2, 3, 4 Moreover, SARS-CoV-2 can also be transmitted through the saliva, and ACE2 has been detected on the mucosa of oral cavity, which is rich in epithelial cells. Therefore, if saliva and feces are both capable of carrying the virus and ACE2 is expressed both in the glandular cells of rectal epithelia and oral mucosa, how can we be sure that sexual intercourse does not represent another way of contagion? We thus hypothesize that practice of certain sexual behaviors could constitute an additional way for the contagion, both directly (eg through oral-anal contacts), or indirectly (eg with exposure of the rectal mucosa to the saliva for lubrication during anal sex).

This issue could be particularly noteworthy if considering that a patient with COVID-19 is actually considered cured after at least 2 upper respiratory tract samples negative for SARS-CoV-2 are collected at ≥24-hour intervals. Nevertheless, it has been demonstrated that patients can persistently test positive on rectal swabs even after negative results for nasopharyngeal testing. This means that the gastrointestinal tract may continue shedding the virus and that fecal-oral, or eventually sexual, transmission may be possible despite the apparent recovery. Indeed, some authors recommend that real-time reverse transcription polymerase chain reaction be routinely performed to test for SARS-CoV-2 from feces.

Patients' sexual habits are often not investigated. These observations highlight the need for physicians, and dermatologists in particular, to strongly discourage sexual practices if infected during the pandemic COVID-19. Indeed, beyond the hypothesized possibility of a direct sexual transmission, sexual intercourse involves close contact that inevitably expose individuals to the risk of contagion. Refining the questions in epidemiologic surveys and conducting extensive studies of the mucosal sites (genitals included) of SARS-CoV-2 shedding may perhaps confirm our hypothesis, allowing for a greater understanding about SARS-CoV-2 transmission routes and effective strategies to control infection spread.