The Covid-19 vaccines were hailed as a miracle upon their arrival. They were delivered earlier than anyone thought possible and proved exceptionally effective in preventing hospitalizations and deaths. More than 80 percent of all Americans, and more than 90 percent of adults, received at least one dose of the vaccines, remarkable penetration in a country where less than half of people get their flu shot every year.

But so far this year, just 7 percent of adults have received a dose of the new vaccine formulation that became available in September — compared to 28 percent who have gotten a flu shot.

This raises a question that would have seemed unthinkable three years ago: What if we make a miraculous vaccine and nobody wants it?

Ever since that first shot, the public’s interest in subsequent Covid-19 vaccines has been steadily dropping. Less than 70 percent of the US finished their initial two-dose vaccine series. Less than 20 percent of the country received last year’s bivalent booster shot.

Experts say the public’s disinterest in the latest Covid shots is likely a combination of poor messaging from authorities, a diminishing fear about a virus that three years ago was wholly unknown, and the political polarization of the pandemic itself. But whatever the reasons, that vaccine ambivalence still poses a health threat.

Elderly people and very young infants continue to have a higher chance than the rest of the population that they will be hospitalized with Covid-19. Vaccination rates have fallen off for the former group, who are also most likely to die from an infection, and they were never strong to begin with for the latter; 95 percent of children under 4 are unvaccinated. About half of seniors being hospitalized for Covid-19 these days have never gotten a vaccine, experts say, affirming that the unvaccinated continue to be hit much harder by the virus.

Infectious disease experts saw 2023 as a pivotal year for the country’s transition out of the pandemic. It would test whether the US health system could marshal a strong response to the winter Covid-cold-and-flu season, specifically through a successful vaccination campaign. The dismal start to that campaign may force a difficult question upon the public health community: If Americans don’t care about getting vaccinated against Covid-19 anymore, what do we do now?

Why Americans aren’t getting their Covid-19 shots

Part of the story is simply human nature. Covid-19 arrived in 2020 behaving strangely (with so much asymptomatic transmission) and incurring a deadly toll (the first iteration of the virus was notably more virulent than the flu). Much of the economy shut down and people were confined to their homes. It was a scary time and vaccines offered hope for a future in which not only would you be less likely to get seriously ill but that life could get back to normal. When shots went out to hospitals, pharmacies, and vaccination clinics in December of 2020, Americans were eager to get them.

But three years and multiple new vaccine formulations later, the novelty is gone.

Americans aren’t as worried about Covid-19 now. About two-thirds of US adults said they were not concerned about getting seriously ill from Covid-19 in a September survey from the KFF health policy think tank. That figure was about the same for the flu and RSV, suggesting Americans have come to view the novel coronavirus as a similar health risk to other cold-weather illnesses that have been circulating for a long time.

“People aren’t scared of this virus anymore,” Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, told me.

As evidence, he recounted that he had ridden the subway with “100 screaming, maskless” football fans heading to the Eagles-Cowboys game. “No one on that subway car had a mask on,” he said. “We are close to winter, and this is in theory a winter virus.”

Familiarity is one part of that change in attitudes. Another is political polarization: Republicans, both the rank-and-file and their political leaders, have grown more and more hostile toward the Covid-19 vaccines, with a general skepticism toward government mandates spilling into conspiracy theories and disinformation. (Offit marveled at that turn of events: These vaccines are “the most amazing medical and scientific accomplishment” of his lifetime and “the greatest accomplishment of the Trump administration.” And yet.)

Only 25 percent of Republicans said in KFF’s September poll that they would get the latest version of the Covid-19 vaccine this fall or winter. Another 40 percent of the party said they had received an earlier dose but would not get the new shot and 36 percent said they had never been vaccinated at all. To compare, 45 percent of independents said they would get the new shot and 69 percent of Democrats said they would. While reality does not exactly match up to those responses, the gap between Republicans and the rest shows partisanship is driving vaccine attitudes.

“It’s become part of somebody’s identity that they’re not somebody who gets Covid shots in particular,” said Dr. Céline Gounder, a senior fellow at KFF and editor-at-large for Public Health at KFF Health News. “That may spill over to vaccines, but it starts with Covid.”

There are worrying signs of a more general resurgence in vaccine skepticism: 3 percent of US schoolchildren reported a vaccine exemption for the coming school year, the highest share on record according to the CDC. Ten states have an exemption rate above 5 percent; only two did three years ago.

But while that uptick is worrying, it is clear, as Gounder noted, that Covid is a special case for Americans. Flu vaccination rates last season were in line with rates from before the pandemic: Lower than you’d like (57 percent for kids, 46 percent for adults) but historically unremarkable. Flu vaccinations this year are on track with last year’s pace, according to the CDC.

People were already accustomed to the annual flu vaccination campaign before the pandemic and they seem to be mostly sticking to old habits. So why do so many seem so immune to the public health community’s plea that they get a Covid-19 shot at the same time?

The other factor may be that Americans have become inured to such public health messaging after years of living through a public health emergency.

Partly, the vaccines are a victim of their own success. The initial clinical trials reported incredible results not only in stopping severe disease (the primary public health goal) but in stopping any illness at all. The gobsmacked headlines may have led the public to expect to never get sick at all, and public health messages failed to break through with the reality check that while you may still feel sick, it is much less likely you’ll end up in the hospital — and that should count as a win. When reality didn’t meet expectations, seeds of doubt and distrust were sown.

For the later shots, Gounder said the public health messaging itself, which generally encourages everyone to get another Covid-19 shot, may be part of the problem. People are more familiar with the virus now — and that means many have a general idea of how it works. They may know, for example, that age and chronic health conditions are the best indicators of one’s risk of serious illness or death from an infection.

Other countries, such as the United Kingdom, have targeted their recommendations to people over 65 and people at a heightened risk because of their health, as well as the people who live with and care for those at-risk folks.

The United States has to date instead erred toward simplicity with its vaccine messaging and recommendations: Everyone older than 6 months is recommended for yet another shot. Experts acknowledge there is an argument for that strategy. But as Covid-19 has become a more familiar illness and people have a better understanding of it, there may be a better argument for a more nuanced approach.

At this point, people have likely lived through an infection of their own and have firsthand experience with Covid-19. The initial vaccination campaign was crucial because people had no immunity to Covid-19 at all; the population was naive. But the public health reality has changed three years later: Most people have either been vaccinated or infected or both.

So when the official vaccine guidance remains largely unchanged, and the messages public health authorities are sending fail to acknowledge the varying risks or that people do possess some immunity, they may end up being ignored.

“I understand some of the skepticism,” Gounder said. “When you tell everyone you’re all at risk, get your shot, it doesn’t correspond with your lived reality.”

What the future may hold for Covid-19 vaccines

There are short-term steps the US could be taking to bolster Covid-19 vaccine uptake, particularly for the most vulnerable. Additional funding for nursing homes to hold vaccination campaigns, for example: Only 17 percent of nursing home residents are up to date on their shots. Experts also stressed the importance of communicating to people that the very young can get seriously ill with Covid-19; even if they don’t die, the health complications can be serious. Gounder said she’d like to see that messaging start with more of a focus on pregnant women, who can pass some immunity to their unborn child.

But there is a larger question brewing when only 10 percent of the US population is showing much urgency about getting a Covid-19 vaccine: How are we going to keep doing this?

Pfizer said in September that it expected about one in four Americans to get the latest shot. Though there is still time, current vaccination rates are well short of that goal. It is an open question how the for-profit pharmaceutical manufacturers who produce these vaccines will respond to what the market is telling them.

Gounder said it is difficult to imagine a cessation of Covid-19 vaccinations entirely. The public health case for immunizing the elderly in particular is strong. But drug makers may scale back their production, especially if the government’s recommendations become more targeted.

The federal government is putting a lot of money behind pharma’s pursuit of a universal Covid vaccine, but until those efforts bear fruit (if they ever do), there may also be less interest in producing new formulations of the vaccine after uptake for this season’s new shot was so paltry.

The known unknowns for the future, which could spur another round of investment and interest in updated Covid-19 vaccines, are biological. The virus has been evolving and will continue to evolve and could, in theory, reach a point where the current vaccines are ineffectual.

The other question mark is inside of us. The reason many people still enjoy protection from serious illness is because our body’s T-cells are familiar with the virus and can activate when they detect it. They may not be able to stop an infection entirely (that is the role of antibodies, which are quicker to fade) but they can stamp out the virus before a person becomes too sick.

What we don’t know today is how long our T cells’ memory will last, and how durable that immunity really is. The only way to find out is for more time to pass.