I wrote before that there were parallels between combatting foreign enemies and combatting plagues. I need to be more precise: there are anti-parallels too.
Before I go on, I need to remind us that using armies for internal crime control almost always turns out badly. You don't want to even think about it unless you have an insurrection (political or Mexican-cartel) already. It turns corrupt very easily.
Within a country, or tribe, or even a family sometimes, we rob and kill each other. You might be able to reduce that, but you'll never get rid of that problem. Punishment works better than no-punishment; the rest is details I don't want to get into right now.
But crime, so long as it doesn't grow into a state-within-a-state, is something we can keep under enough control that we, as a group, can live with it. Individual action can make a difference. Don't go there alone; don't hang around people using drugs; don't fool around with somebody else's squeeze; carry your own weapon; etc. That'll be no comfort to me when I get mugged, of course, but human nature isn't something I can change, and a lot of the "cures" make the problem worse.
Invaders are another matter. Their scale is already large enough that individual action is of no use, and the scope of the potential damage they do is not limited. Unless there's no possible way of fending them off, and sometimes even then, you band together to provide and support your warriors. In an ideal world, in which generals are more interested in winning wars than in politics, you trust the generals to be careful with the lives of the soldiers, but be willing to expend them in order to stop the enemies. You expect some of your soldiers to die. Traditionally, and wisely, the burden of that risk falls on the men. The risks of losing fall on the women and children too.
You have to measure your enemy. How big is the risk, and how much effort must you marshall to deal with it?
You have to expect setbacks and mistakes. If a general makes too many mistakes, he (one hopes) is removed. How many is "too many" is a judgment call, and I wish I could be more confident about how well that's usually done. But you're supposed to be able to point to the responsible people. After the Fitzgerald crashed into a freighter, Bryce Benson needed to move ashore permanently, but when the extent of the problem came out, the Secretary of the Navy should have gotten the axe too. And somebody needed to explain matters to politicians who want to "show the flag."
The demands of a war sometimes require infringements of rights. Someone needs to be responsible for that, and there needs to be a clear end to it as well. Otherwise it's hard to claw the rights back afterwards. Power is addictive, and especially the power to suppress dissent.
Diseases happen. Some of them are random, and some of them are self-inflicted stupidity, and some happen because somebody else was careless or stupid--or malicious. Usually we worry along somehow, trying not to be too stupid. Eventually something kills us. It is possible to spend infinite resources in health care--the demand will grow to match the supply, but in the end everybody dies. Some projects make health better overall (sewage treatment), and others have opportunity costs that make things worse.
Deadly epidemics are another matter. Their scope is large enough that individual action is of little use, and the damage they can do is not very limited. If you hope to live, you need to coordinate with your neighbors and essential workers to simultaneously provide food/water/waste disposal while minimizing the chance of contagion. Without supplies and waste disposal you will die of hunger or some other disease, but each contact brings a probability, however small, of contagion and the plague. Unless the plague discriminates somehow, the risk falls on everyone.
You have to measure your enemy. How big is the risk, and how much isolation and effort must you use to deal with it?
For example, the current plague is relatively mild as these things go. It isn't as contagious as measles, or as deadly as ebola, or as apt to hide out as anthrax. That's not cheering to the crippled or dying, but it's true. FWIW, I'm getting into the higher risk category, and expect that I'll get it one of these years.
As an exercise, imagine a plague, spread by touch or fomites, with 30% mortality rate. Quarantines would be enforced at gunpoint, and transportation would shut down--including vital supplies. Some people would starve or die of unrelated diseases. You'd have to balance deaths by plague against deaths by starvation or lack of critical drugs. (And by quarantine I mean both town border enforcement and locking the sick in their home until the inhabitants either die or survive the illness.) In an ideal world, there would be people clearly responsible for these decisions, and they would be careful with people's lives, but willing to let some die that more would live.
You expect some random failures, and some mistakes, but you also hope that those who make too many are removed and replaced with more competent people. There needs to be a clear chain of responsiblity. Different states may wind up with different policies, especially if the plagues hits them differently.
Combatting the plague may require infringement of rights, including the right to travel--even for vital things. Someone has to be clearly responsible for that, and there needs to be a clear end to it as well.
There would be plenty of opportunity for abuse, score-settling, and profiteering--just as in a war.
Some of the parallels are pretty clear: collective effort, people sent to likely death, redirection of resources, tight controls on ordinary life, and a need for chains of responsibility/command.
Both bring a strong temptation to mission creep: using the military to police, or to do public works service; expanding the Department of Plague Defense to address lesser diseases as well. ("If we can stop smallpox, why can't we cure tooth decay? Let's ban sugar.") Do I have to explain why both are very bad?
And, as I wrote before, both are very likely to be caught with their pants down when a real plague or war breaks out.
There are anti-parallels. In times between epidemics, the Department of Plague Defense will want to justify its existence. Politicians would tend to favor this: increasing "free" medicine plays well in the ballot box. In times between wars, the military gets more interested in internal empire-building and politics than actual readiness. Politicians tend to be eager to cut military budgets in favor of their personal priorities.
People understand volunteering for war well enough--the dangers are clear, the enemy is clear (well, usually), and what to do is clear. Plague defense is more abstract, and much creepier. You feel more exposed and helpless with an invisible enemy.
In my schema for this kind of program, the CDC's mandate is far too broad--they'd be more analogous to police than army. I'd not want to give them the kind of emergency authority the DPD would need--especially when they show an interest in broadening the definition of epidemic to include crime. I think they need some housecleaning, not greater scope.
