This isn't a normal situation, but it's also not the black death. If the IFR were say 3%, then maybe you roll the dice on a vaccine that we're not sure about the complications on and give it to anybody and everybody as quickly as we can manufacture it.
For an IFR of .4% and that has most of its mortality come from identifiable populations, it's not going to make sense to vaccinate a lot of healthy, low risk people without determining the likelihood of adverse effects, unless we are willing to admit that we are normally wayyyy too cautious with approvals of drugs and vaccines.
The case fatality rate in Mississippi for 18-29 years olds is 0.087%. So not quite 9 out of 10,000 confirmed cases die. Depending on what percentage of cases you think Mississippi catches in that age group, that's somewhere between .01 and .05 IFR for people that age, or maybe less if you think a disproportionate number of 18-29 years olds are asymptomatic. That's a pretty serious disease. I certainly don't want any of my kids facing a 1 in 10,000 chance of dying. But that's also for all 18-29 year olds in possibly the unhealthiest state in the nation. If you limit it to college athletes, you're probably looking at dropping that by an order of magnitude maybe? Certainly you're getting to the levels where even pretty rare adverse effects can equal any benefit from reducing the chances of getting infected to begin with.