Abstract
COVID-19 may influence human fertility and sexuality in several ways. Different cell types in gonads show a constitutive expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine subtype 2 (TMPRSS2), which provide potential entry pathways for SARS-CoV-2. In addition to the biological effects of a COVID-19 infection on the gonads, the impact of the ongoing COVID-19 pandemic on mental health issues and sexual behavior may affect reproduction. This review summarizes the current knowledge on the influence of COVID-19 on the gonads and discusses possible consequences on human fertility. In this context, the close interaction between the hypothalamic-pituitary-adrenal axis and the hypothalamic-pituitary-gonadal axis in response to COVID-19-related stress is discussed. Some women noticed changes in their menstrual cycle during the COVID-19 pandemic, which could be due to psychological stress, for example. In addition, occasional cases of reduced oocyte quality and ovarian function are described after COVID-19 infection. In men, COVID-19 may cause a short-term decrease in fertility by damaging testicular tissue and/or impairing spermatogenesis. Moreover, decreased ratio testosterone/LH and FSH/LH in COVID-19 compared to aged-matched healthy men has been reported. Available data do not suggest any effect of the available SARS-CoV-2 vaccines on fertility. The effects of long COVID on human fertility have been reported and include cases with premature ovarian failure and oligomenorrhoea in women and erectile dysfunction in men. Despite the increasing knowledge about the effects of COVID-19 infections on human gonads and fertility, the long-term consequences of the COVID-19 pandemic cannot yet be assessed in this context.