Women have a more "advanced" immune system, since many of the genes involved in the immune system are located on the X chromosome. The downside of this is that women are also more at risk of auto-immune disease.

https://www.nature.com/articles/nri2815?proof=true

There was a post on HN a few days ago about a study that found low testosterone levels were correlated with worse Covid-19 outcomes. I think vitamin D is technically a hormone (or maybe is hormone-like?) so I wonder if it’s absorbed differently by men than women. Or maybe low testosterone is just a side effect of a vitamin D deficiency in men.

It could also be low levels of sex hormones in general - having neither estrogen nor testosterone in your body causes osteoporosis, for example. Excess testosterone is metabolized into estrogen, as well.

But the endocrine system is ferociously complex - maybe endocrine abnormalities are a proxy for obesity, or an underlying thyroid issue etc.

According to [0], vitamin D deficiency is associated with higher free testosterone in men and lower estradiol in women. Higher testosterone is associated with cardiovascular problems, which are a big COVID risk factor.

But that doesn't jib well with the study you find, so I dunno what to make of it.

0. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5218632/#__ffn_...

I think that low testosterone levels is correlated with being older which is correlated with worse Covid-19 outcomes, so age is the important factor here.

One study suggested that progesterone was a factor in reducing viral levels.

Men also might have other factors compared to women. As an example 2x as many men vs women die in auto accidents.

I was surprised to hear that figure! I did my own research and it appears to be correct (in fact, it's greater than 2x in recent years). However, that ratio ignores vehicle miles driven. Once you account for that, the comparative ratio is slightly lower:

https://www.iihs.org/topics/fatality-statistics/detail/gende...

> The number of driver fatal crash involvements per 100 million miles driven in 2017 was 62 percent higher for males (2.1 per 100 million miles traveled) than for females (1.3 per 100 million miles traveled). Rates were substantially higher for males than for females ages 16-29, but were only slightly higher for ages 30 and older. The gender difference was largest among drivers ages 20-29.

So in some sense the real figure is 1.62x for men as women per mile driven, although (1) men driving more miles is still a real thing and as a result more men die, and (2) I don't know to what extent super-distance drivers (like commercial truck drivers, who skew heavily male) are putting their finger on the scale.

If you ignore teenagers, that difference comes out to 1.59x; and leaving out persons <30, 1.46x. Still much higher than 1.0.