AbstractBackgroundSevere acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) may affect the male reproductive system as it uses angiotensin‐converting enzyme (ACE)2, which is expressed in testicular tissue, as an entry point into the cell. Few studies have evaluated the long‐term effects of mild coronavirus disease 2019 (COVID‐19) on testicular function, and insulin‐like factor 3 (INSL3) levels have not previously been assessed during acute SARS‐CoV‐2 infection.ObjectivesThe aim of the study was to assess the impact of acute SARS‐CoV‐2 infection on testicular function including INSL3 and the presence of SARS‐CoV‐2 RNA in semen in non‐hospitalised men with mild COVID‐19.Materials and methodsThis longitudinal study included 36 non‐hospitalised SARS‐CoV‐2‐positive men (median age 29 years). Inclusion was within seven days following a positive SARS‐CoV‐2 reverse‐transcription polymerase chain reaction test. Reproductive hormone levels, semen parameters, and the presence of SARS‐CoV‐2 RNA in oropharyngeal and semen samples were assessed during acute SARS‐CoV‐2 infection (baseline) and at three‐ and six‐month follow‐up. Wilcoxon matched‐pair signed‐rank (two samples) test was used to assess time‐related alterations in reproductive hormone levels and semen parameters.ResultsLower plasma testosterone (T) (total and calculated free (c‐fT)) and higher luteinising hormone (LH) concentrations were observed during acute SARS‐CoV‐2 infection (baseline) compared to three‐ and six‐month follow‐up. Consequently, ratios of c‐fT/LH were lower at baseline compared to three‐ and six‐month follow‐up (p < 0.001 and p = 0.003, respectively). Concomitantly, lower INSL3 concentrations were observed at baseline compared to three‐month follow‐up (p = 0.01). The total number of motile spermatozoa was also lower at baseline compared to six‐month follow‐up (p = 0.02). The alterations were detected irrespective of whether the men had experienced SARS‐CoV‐2‐related fever episodes or not. No SARS‐CoV‐2 RNA was detected in semen at any time point.Discussion and conclusionThis study showed a reduction in testicular function, which was for the first time confirmed by INSL3, in men mildly affected by SARS‐CoV‐2 infection. The risk of transmission of SARS‐CoV‐2 RNA via semen seems to be low. Febrile episodes may impact testicular function, but a direct effect of SARS‐CoV‐2 cannot be excluded.