We have to ask, what if the pandemic never really ‘ends’?

WASHINGTON — For nearly a year, most of us have assumed this pandemic could end only one way: herd immunity. Maybe we’d get there by staying inside until a vaccine arrived, or maybe we’d all give up, catch COVID-19 and acquire immunity the old-fashioned way. Almost none of us considered whether it was possible that neither of those things might happen.

So let’s ask: What if the virus gets more contagious and even more lethal, like the variant first identified in Britain, instead of less deadly, like the 1918 flu? What if the virus keeps reinventing itself and evading our immune defenses, so much so that it’s not possible to reach herd immunity without continually updated vaccinations? What if the pandemic never really “ends”?

The situation in Manaus, Brazil, is making me ask those questions. And I don’t like the answers.

Manaus, a city of 2 million in Brazil’s Amazon region, basically followed the prescription of lockdown skeptics: Restrictions were few, and infections were many. By last month, some scientists estimated 75% of the population had already had the disease — putting Manaus at least close to herd immunity, if not already there.

Then Manaus got hit by its deadliest wave yet. Hospitals ran out of oxygen; patients who probably could have been saved asphyxiated. Many of the dead ended up in mass graves. Given prior infection rates, the volume of emerging cases in Brazil suggests that a variant, known as P.1, may be infecting people who’ve already survived COVID-19 once. And, possibly, making those it does infect sicker.

“What has been said before, that this is a strain more transmissible but not more severe — that’s not what is happening in Manaus,” epidemiologist Noaldo Lucena told The Washington Post last month. “This isn’t a feeling. It’s a fact.”

There are similar worries about another strain emerging in South Africa — though there are reasons not to despair quite yet. For one thing, Manaus might not have had as many infections as researchers estimated, so reinfection may not be the problem some fear. But even if things are as bad as they look, we should be able to develop new vaccines that contain the nascent variants. In theory, with global vaccination, caseload numbers could be crushed so low that the virus has nowhere to go and no time to evolve around most people’s immune defenses.

The problem is that life happens not in theory but in practice. Poorer countries probably won’t be fully vaccinated for years — and, for that matter, the United States might not be, either. Fewer than half of U.S. nursing home workers got vaccinated in the first round of on-site distributions at their facilities. What might resistance rates look like among Americans who don’t work with our most vulnerable? What if only 50% of Americans get vaccinated, about the share of people who get flu shots? What if it’s even fewer?

In that case, our best hope is probably that vaccine skeptics who assume that they’ll be immune after they get infected realize their mistake when another wave materializes. They might opt to take their chances on vaccination rather than risk a third bout of COVID-19. In this situation, many people would die. But it’s almost certainly better than other possibilities.

For vaccine skeptics might dig in, creating reservoirs of infection in which new variants can arise — for example, by spreading to immunocompromised people whose infections could function as laboratories where the virus effectively experiments with ways to evade immune defenses. And since we clearly won’t keep locking ourselves down forever, we might decide, as a nation, to accept greater death rates rather than doing what it would take to actually shut down transmission.

Alternatively, we could get tired of all the dying and take the kinds of strenuous steps that have so far been off the table in the United States: making it near-impossible to live and work without proof of current vaccination. Require people to show their card before boarding a plane or cruise ship, attending a concert or movie; make such evidence mandatory for occupations as varied as nursing assistants and waitresses. And use a central, instantly checkable database so the certificates can’t be forged.

It’s not clear to me which of these outcomes is more likely. What’s obvious is that they’re all terrible. Yet it also seems clear that at least one possibility is even worse.

Unfortunately, it’s easy to imagine Americans dividing on this, as they have on so much else, to the point where everyone gives up on a unified solution. The risk-averse — disproportionately affluent, educated and Democratic-leaning — might wall themselves off into well-vaccinated enclaves, leaving the rest of America to itself. I’m not sure that any nation could survive half-vaccinated and half-free. But I’m quite sure that I’d rather not explore that question any further.