July has been the best and the worst month so far for Americans who were hoping for an expeditious resolution to the covid-19 crisis.

It is the worst month because America’s covid response has been a vast and humiliating disaster; as European caseloads decline toward zero, the United States is flirting with new records. While Europeans resume dinner parties, the United States is wondering if it can reopen primary schools. Americans who have been trapped inside for months are starting to feel despair clawing at them — and worse, looking across the Atlantic to realize their suffering isn’t even necessary.

Nonetheless, July was the best month because we have gotten encouraging news on two vaccines, one from Pfizer/BioNTech, the other from Moderna. Both showed strong results in early trials, and both companies are plowing ahead into the final stage of testing. Anthony S. Fauci, the federal government’s top infectious-disease expert, has publicly stated that he thinks we might have a vaccine by the end of the year.

That’s far from a guarantee. But it is real enough, and tantalizing enough, that we need to start planning now, so that we don’t screw up the vaccine the way we screwed up the first phase of the coronavirus response.

To defeat covid-19, we may well have to have to vaccinate everyone, or as close to everyone as we can. That kind of vaccination campaign — the kind that could really make everything go back to normal — is going to take a vast, coordinated public effort on a scale that we may not have seen since the United States rolled out draft cards and ration books during World War II.

That’s not yet commonly understood, because most people think of a vaccine as an individual benefit: You get a shot, or maybe a series of them, and then you’re immune. And yes, vaccines often do work that way. But the protection they provide is imperfect.

Some people who are vaccinated never muster a strong, protective immune response; for common childhood vaccines, the rate of vaccine failure is 5 to 15 percent. That failure rate is likely to be higher in older people, whose immune systems aren’t so robust. But even when the shots do work, the effectiveness often wanes over time, which is why you have to get booster shots for tetanus.

Yet we’ve nonetheless managed to eliminate (or nearly so) once-common childhood diseases through “herd immunity” — a concept you’ve likely been hearing about recently. If enough people have immunity, the virus keeps running into dead ends as it tries to spread, and eventually, burns out. So even though many of us adults have probably lost some of the immunity that we once acquired through childhood vaccinations, we’re still safe from those diseases, because we’ve thoroughly immunized the main reservoirs — school buildings full of runny-nosed children — where those diseases used to spread.

So people who are imagining that as soon as we get a vaccine they can get a shot and go on with their lives need to be aware of the real risk that we get a vaccine fairly quickly, but it’s only modestly effective. Moreover, its effectiveness would be particularly modest in the people we are most eager to protect: the elderly and immunocompromised. Which means that we need to have plans now to get everyone immunized, so that everyone can safely go outside.

The logistics alone are daunting. We might not reach true normal until a sizable majority of the country is vaccinated, and our traditional method for fighting infectious disease — require vaccination to attend primary school — won’t achieve that. How do we purchase, store and distribute all those doses? How do we keep track of who has been vaccinated, particularly if vaccination requires multiple doses? All this needs to be resolved at the federal level, as much as possible, because in a country as open and mobile as the United States, we’re all only as well as our sickest fellow state.

Such a response cannot be mounted on the fly. We need to be building the capacity right now, even if that means that we staff up agencies and buildings that sit idle for a year as we wait for the right vaccine candidate.

But the logistical problems seem almost trivial compared to the political problems. The covid-19 response has become almost hopelessly politicized, even over small precautions such as masks. Resistance is likely to become stiffer still when authorities want to inject something into someone’s body. Especially since that resistance will tap into preexisting reserves of anti-vaccination fervor that were already overflowing on both the right and the left.

President Trump, who has done more than any other figure to polarize our covid-19 response, will undoubtedly fan the flames of whatever resistance does arise, particularly if he loses in November. One can imagine a solution that would bypass his interference — a serious bipartisan congressional commission to make recommendations, a Republican leadership that enthusiastically promotes them. But if we want this country to get back to normal any time soon, we’ll need to do more than imagine it.

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