Study of SARS-CoV-2 in semen from asymptomatic donors with the presence of virus in nasopharyngeal swabs.

RESEARCH QUESTION: Is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) present in semen samples from asymptomatic donors who have positive virus results from nasopharyngeal swabs? DESIGN: Nasopharyngeal PCR was performed on 1943 sperm donors between January 2021 and March 2022. The result was positive for 140 donations, and the presence of SARS-CoV-2 could be studied in cryopreserved semen from 84 of these donors. This included 67 participants in whom the quality of fresh semen could be compared with the previous donation, the day of the PCR-positive nasopharyngeal sampling and the first subsequent donation. Semen donations were cryopreserved following total semen (n = 26) or ready-to-use (n = 58) protocols. The presence of SARS-CoV-2 in cryopreserved samples was determined by reverse transcription PCR. Semen quality (volume, concentration and progressive motility) was evaluated in accordance with World Health Organization 2010 recommendations. RESULTS: SARS-CoV-2 virus was not detected in any cryopreserved total semen or ready-to-use samples. No significant differences in semen volume, concentration or progressive motility were observed between the last previous donation, the day of the positive PCR nasopharyngeal sampling and the first subsequent donation. CONCLUSIONS: The lack of detection of SARS-CoV-2 in semen samples from asymptomatic individuals infected with SARS-CoV-2 supports the safety of assisted human reproduction treatments using this type of sample.

Maximum number of children per sperm donor based on false paternity rate.

PURPOSE: The aim of this study is to estimate the weight of each relevant factor in such unions of inadvertent consanguinity and to determine a "reasonable" limit for the number of children per donor, matching the probability of inadvertent consanguinity arising from the use of sperm donor in assisted reproduction with that of such a union arising from false paternity. METHODS: In this study, we applied to Spanish data a mathematical model of consanguineous unions, taking into account the following factors: maximum number of live births/donor, fertility rate, average number of births per donor in a pregnancy, donor success rate, matings per phenotype, number of newborns/year, and number of donors needed in the population/year and births by false paternity. RESULTS: In Spain, the number of inadvertent unions between descendants of the same donor in Spain has been estimated at 0.4/year (one every two and a half years), although this frequency decreases as the reference population increases. On the other hand, the frequency of unions between family members due to false paternity has been estimated at 6.1/year. Thus, only 6% of such unions are due to the use of donor sperm. CONCLUSION: A total of 25 children per sperm donor are needed to align the probability of inadvertant consanguinity arising from the use of assisted reproduction with that due to false paternity. Therefore, we consider this number to be the maximum "reasonable" number of children born per donor in Spain.