This article says, “People over 65 are considered at a higher risk for Covid-19 infections. This may be in part due to age…”
The CDC says people over 65 may get more severe versions of Covid-19 IF they catch it; it’s a conditional probability. I haven’t seen any research that says people over 65 are more susceptible, i.e., more likely to catch it, given the same exposure as a younger person.
Also the reports on age and coronavirus do not usually separate out those over 65 in nursing homes (less than 1% of the population but 1/3 of all deaths — as high a 66% in some states). Nor do they separate seniors with pre-existing conditions.
Age doesn't always weaken the immune system. There’s a huge variation due to fitness and genetics.
When they factored out underlying conditions, age differences melted away.
Men also get more severe cases and die far more frequently but we’re not seeing reports telling them to stay home and let their wives and sisters go out for them. There’s a political and social agenda in these reports.