> The sperm concentration of the COVID-19 negative group was significantly higher than those in the COVID-19 positive group. No statistically significant difference was detected between the groups for sperm motility and morphology. It was observed that men with COVID-19 had decreased sperm concentrations suggesting that COVID-19 may have a negative effect on male fertility. However, in the long term, more comprehensive studies with a large sample size are needed to understand better the changes in sperm concentration.
Given what I know about the modern man in general (being one, being around them), it's possible that more healthy men do not catch covid and also have higher sperm counts to begin with. Not sure if the study took that into account.
> it's possible that more healthy men do not catch covid
I'm pretty certain that that is not true. There is no study I've seen that correlates (either positive or negative) susceptibility to COVID with general health.
- https://onlinelibrary.wiley.com/doi/10.1002/jmv.27971