When can everyone in the US get a Covid-19 vaccine? We still don’t know.

As America’s bumpy Covid-19 vaccine rollout continues, a lot of people still have one very big question: When can I get a Covid-19 vaccine?

For the vast majority of people, we don’t know yet. There are too many variables, from how much the new federal government can improve vaccination rates to which vaccines get approved for use in the future, muddying any potential predictions for vaccines.

Under federal guidelines and states’ current plans, the US has made vaccines available to limited groups of people: health care workers and nursing home residents first, with older Americans (particularly 65 and up) and at least some groups of essential workers to follow.

For the rest of the country, how quickly you might get a vaccine depends entirely on the pace of the rollout; that will dictate when it’s finally your turn in the line. And right now, too much is changing to get hard answers for when everyone will be able to get a vaccine.

As it stands, about 1.2 million people in the US are getting either their first or second Covid-19 vaccine dose a day. With nearly 22 million Americans already getting at least their first shot, the country is currently on track to hit a 75 percent vaccination rate — a possible herd immunity threshold — as late as early 2022. At current rates, getting every person in the US vaccinated — a lofty goal — could take until as late as summer 2022.

That’s definitely alarming, given that no one wants this to take until next year. But experts and government officials expect the pace of vaccinations to start to pick up in the coming months — although that can only happen if the Biden administration, states, and vaccine producers fix a host of problems hindering America’s vaccination campaign.

There are still a lot of unknowns

President Joe Biden this week revised his previous goal of 1 million shots a day (for 100 million shots in his first 100 days in office) — which the country neared before Biden took office — to 1.5 million a day. That would get the US to the 75 percent threshold as late as the end of this year and the 100 percent mark as late as spring of next year.

But as Biden has repeatedly cautioned, these goals are only the beginning. Experts have called on the government to increase the rate of vaccination to 2 million or 3 million shots a day, which could allow the country to reach 75 percent in the summer or fall and vaccinate everyone else by the end of the year. That would mean herd immunity, when the enough of the population is protected that the virus can’t spread easily, would arrive sooner, but going that quickly will likely require a much more involved federal campaign than we’ve had in the first few weeks of the vaccine rollout.

Even if the country doesn’t boost vaccination rates, there’s another big factor that could speed up the vaccine campaign: a one-dose vaccine. The two vaccines from Pfizer and Moderna approved by the federal government currently require two doses, split weeks apart. But other companies, like Johnson & Johnson, are working on one-dose vaccines. If they prove effective and get federal approval, that could speed up the vaccination process by as much as twice over.

But that depends on these vaccines getting approved and being as good as Pfizer and Moderna vaccines that the data shows to be 90-plus percent effective against preventing Covid-19. Otherwise, a lot of Americans may want to continue getting a more demanding but more effective two-shot regiment — limiting the one-shot vaccine’s potential impact. (The latest reported results show Johnson & Johnson’s vaccine is very effective, especially at preventing severe illness and death, but may not be as effective, particularly at stopping mild disease, as the two-shot vaccines.)

Meanwhile, federal regulators still haven’t approved a vaccine for children. And it remains unclear when they will — it’s a matter of getting the proper trials and data first.

Another variable is how many Americans actually want and will get a vaccine. Currently, surveys suggest about one in five Americans are still hesitant. That might be bad news for hitting herd immunity and sufficient population protection. But it could be good for people who want to be vaccinated quicker, since it means less competition.

All of that is to say that there are still a lot of unknowns: Can public officials and private actors improve the rate of vaccination dramatically? Will vaccines get approval, including for kids? Will those approvals speed up the process? How many Americans want to and will get a vaccine?

The answers to those questions, and more, will dictate when everyone who’s waiting for a vaccine can actually get one.

What’s currently going wrong with the vaccine rollout

For now, the most pressing problem to everyone getting a shot still seems to be the “last mile” of the distribution chain, when vaccines go from storage to shots in arms.

If you look at America’s vaccine rollout, it can seem like a bunch of different problems from place to place — from vaccine doses going unused to equipment breaking down to long lines and insufficient staffing at vaccination sites.

But many of these issues are likely rooted in one overarching problem: a lack of federal support for notoriously underresourced public health agencies.

To put it another way: If you asked a bunch of underfunded public health agencies to do a big task in a large, diverse country, then refused more support to help them carry out this task, you would actually expect a lot of different problems to arise by virtue of the country being a big, diverse place. The root problem is a lack of federal support, but how that problem looks in different places will vary widely based on geography, demographics, local and state political environments, and more.

“States aren’t totally off the hook, but what we are seeing is the result of lack of resources and strong guidance (and the historical way in which public health is organized and delivered in the US),” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me this week.

This is the problem that Biden has promised to address. There are various ideas in Biden’s $400 billion Covid-19 proposal, which includes $20 billion for vaccines, and broader plans, but the general gist of the proposals is the federal government is going to do a lot more — from building mass vaccine centers to deploying more staff.

It’s the kind of thing former President Donald Trump’s administration rejected, as it took a leave-it-to-the-states approach to Covid-19 and even characterized more support to states on vaccines as a federal “invasion.”

If Biden’s push for more federal involvement works, the rate of vaccinations could speed up, and more Americans will be able to get their shots sooner — perhaps in the summer instead of (please no) next year.

That could also give us a clearer idea sooner of when, exactly, everyone can get vaccinated.

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