By Jessica Moura

Brazilian researchers have identified a previously unrecognized function of sperm that is unrelated to reproduction. A study of 13 patients admitted to the Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil, with moderate to severe COVID-19 showed that male gametes released extracellular traps (in a process called ETosis) in response to the infection. This immune response, which is common to macrophages and neutrophils, had never been observed in mammalian reproductive cells.

"It opens up a new line of research," said Jorge Hallak, a professor at the University of São Paulo School of Medicine, São Paulo, Brazil, and first author of the article. "This may be an innovative mechanism, or it may have always existed, and no one knew."

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in cells more than 3 months after infection in 11 participants, although polymerase chain reaction tests were negative. These findings suggest the potential for drafting a protocol or guidance on when to attempt a pregnancy. "My concern is with assisted reproduction, in which, in general, only one basic spermogram is done, without diagnostic investigation or serology for coronavirus," said Hallak.

Symptomatic infections hinder the reproductive process because symptoms such as high fever impair cell function by triggering increased DNA fragmentation, reduced mitochondrial activity, decreased acrosome reaction, and cell death, thus affecting sperm count and gamete mobility.

The new findings indicate that the impact of SARS-CoV-2 infection can continue for as long as 90 days after symptoms and signs disappear and affect sperm count and gamete quality for even longer. "With the sperm selection technique, you are at risk of taking a cell with viruses and injecting it into the egg. It is not known what changes this may cause to the embryo," said Hallak.

The expert emphasized that the finding contributes to the understanding of reproductive difficulties that previously had no plausible explanation. It serves as a warning against negligence in the evaluation of men in assisted reproductive treatments.

Daniel Zylberstein, urologist and member of the Brazilian Association of Assisted Reproduction, who did not participate in the research, noted that the result comes from a small study that should be expanded to try to develop guidance for doctors.

"There is still no protocol for these cases. The ideal approach would be to wait for complete spermatogenesis, which takes about 3 months, before putting patients on treatment. This often does not happen, and treatment begins shortly after clinical recovery. In the case of moderate to severe COVID-19, this period should be longer than 90 days," he said.

The study suggests establishing a quarantine period for reproduction until the sperm are free of the virus, said Zylberstein. "With infected sperm, it makes no sense to start reproductive treatment. This sperm is spending energy to fight the pathogen. Assisted reproduction is expensive and exhaustive and may not have the expected outcome because of SARS-CoV-2 infectivity."