We are, it seems, on the verge of war. A germ war, to be precise, that pits the vaccinated against the unvaccinated and is forcing government officials, universities and corporations to pick sides. A time for choosing awaits us all.

We’re about to enter a strange era not seen since 1905, when the Supreme Court ruled (7 to 2) in favor of state police powers to require vaccines, in that case smallpox, for the benefit of the larger community. Today, such a scenario seems better suited to science fiction. But this is our world now, and we’ve all been inducted to serve.

As covid-19 reemerges through the twice-more-contagious delta variant, forcing many Americans to wear masks again and possibly to discontinue gathering in public places, the message is clear: Either get vaccinated, or prepare to be treated differently.

President Biden has ordered that all federal employees (though not uniformed members of the military) either get vaccinated or wear masks and submit to frequent coronavirus testing. Biden is also urging private companies and the military to do the same.

Duke University has announced that it will require that anyone on campus — students, faculty, staff — provide proof of full vaccination or have an approved medical or religious exemption. Unvaccinated people will have to wear masks and submit to regular testing.

There’s no telling how many more universities, companies and communities will follow suit in the next weeks. But the die has been cast. The approximately 50 percent of Americans who have stepped up to the plate and been fully vaccinated, thus drastically reducing the infection rates (for a while), are fed up. The delta variant is quickly overtaking what progress was made by the willing and is swiftly moving through populations of the unvaccinated. The fear among experts is that as delta spreads, infected people will surround and overwhelm vaccinated people through “spillover infection,” while continuing to retard herd immunity.

There is little goodwill between warring factions. People who don’t want the vaccine argue that it’s still categorized as an emergency-use concoction, the full effects of which remain unknown. This would be a reasonable enough argument were it not for the fact that covid and its mutations pose an emergency that can be contained only by vaccinating as many people as possible.

Those of us who’ve gotten our shots see no point to such reluctance when the alternative is so troubling. Even if most people who contract covid don’t die, more than 600,000 Americans already have. Is that figure too small to give people pause? Do the vaccine-averse figure that losing older Americans and fatter Americans, the most vulnerable to extreme sickness and death, is just the price we pay?

For many people over 65, more than 80 percent of whom are fully vaccinated, compromise is neither rational nor negotiable. Fully 42 percent of Americans are obese, according to the Centers for Disease Control and Prevention, and also at high risk for covid.

It isn’t hard to spot the class war lurking within our germ war. The college-educated are less likely to be obese, probably because they’re more fluent in nutrition and because, having higher incomes, they can afford to buy healthier foods. We learned in the early rounds of this pandemic that the virus is devastating to minorities with unequal access to health care; will one part of the population let that happen again to another part?

I am not unmindful of what this might do to us. The circumstances in which we find ourselves remind me of the worst sectarian fighting during the Iraq War, when former friends would cross the street rather than share a sidewalk with someone who supported or opposed the U.S.-led invasion. Divided families could barely discuss the subject with each other, making holidays and reunions impossible. Relationships dissolved. Bitterness reigned.

Those days seem like a picnic compared with what could happen if almost half the U.S. population, already riven by political discord, persists in making life miserable for the other half. This time the battleground isn’t far away, but in our front yards, schools and workplaces.

The pandemic changed us, we’ve said over and over. But as we measure our progress, it seems reasonable to wonder: Could the next pandemic ruin us? Does any vaccinated person want to be around an unvaccinated person? How will we know who’s who? Will we soon be wearing ID bracelets? Such questions raise another frightening prospect to all of this: With the decisions being made to now wage war on the unvaccinated, are we laying the groundwork for even greater distrust in an already convulsive time?

Cures are sometimes worse than the disease, we’ve heard. I fully support the measures mentioned here, but I also fear we’re about to test that hypothesis in ways never before imagined.