Most vaccine skeptics wouldn’t get a coronavirus shot. That hurts everyone.

The availability of a vaccine for the coronavirus will likely play a key role in determining when Americans can return to life as usual. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, recently announced that a vaccine could even be available by January 2021.

Whether a vaccine can end this pandemic successfully, however, depends on more than its effectiveness at providing immunity against the virus, or how quickly it can be produced in mass quantities. Americans also must choose to receive the vaccine.

According to some estimates, 50% to 70% of Americans would need to develop immunity to COVID-19 — either naturally, or with a vaccine — in order to thwart the spread of the virus. If these estimates are correct, that could mean that nearly twice as many Americans would need to elect to receive a COVID-19 vaccine than those who currently opt to be vaccinated against seasonal influenza. Just 37% of American adults did so in 2017-2018, even in the midst of a historically severe flu season.

Making matters more complicated is the possibility that people who hold skeptical views about vaccine safety — sometimes referred to as “anti-vaxxers” — will not opt to receive the coronavirus vaccine. According to some estimates, about one fifth to two fifths of Americans express reservations about vaccine safety. If most of these individuals forgo receiving a COVID-19 vaccine, they could potentially jeopardize the recovery process.

One of us is a doctoral candidate, and the other is a professor, who both study vaccine resistance. We conducted a study, which is currently undergoing peer review, in which we estimate the number of Americans who report being willing to receive a COVID-19 vaccine once it becomes available. We also investigate the reasons some Americans might refuse the vaccine.

We found that about one-fifth of Americans, and more than half of people who hold skeptical views toward vaccine safety, may be unwilling to pursue vaccination. Although most Americans do plan to get vaccinated, non-compliance rates may be high enough to pose a threat to collective immunity.

On the one hand, a pandemic may be encouraging anti-vaxxers to change their minds. One reason so many Americans doubt vaccine safety is due to complacency — the idea that, because high rates of vaccine compliance have kept us safe from diseases that once reached epidemic proportions in the U.S., segments of the population can hold anti-vaccine views without endangering public health.

Consistent with this view, research finds that when people are concerned that once nearly eradicated diseases might reemerge to reach epidemic levels, people are more likely to trust recommendations from public-health experts. In addition, cross-national survey research suggests that people who live in parts of the world where the threat of epidemics is more likely tend to hold more positive views toward vaccines than the rest of the world.

Studies based on in-depth interviews with parents further suggest that parents who chose not to vaccinate their children are often willing to accept treatments for children with life-threatening illnesses.

On the other hand, it could be the case that anti-vaxxers remain suspicious of a COVID-19 vaccine, when it becomes available. Prominent anti-vaccine websites have already begun circulating misinformation about the COVID-19 vaccine — such as the idea that a vaccine has existed for years and has been kept from public consumption. In addition, recent research suggests that anti-vaccine views are tied to deeply held psychological and moral aversions to inoculation, implying that attitudes may be difficult to change.

We set out to investigate this important question. In a demographically representative survey of 493 U.S. adults conducted April 15, 2020, we investigated whether people who hold skeptical views toward vaccine safety plan to receive a vaccine against COVID-19.

Specifically, we asked respondents whether they would be willing to get vaccinated against COVID-19 once a vaccine becomes available. Nearly a quarter (23%) of respondents said that they would not.

In addition, and consistent with the view that even a global pandemic may not persuade anti-vaxxers to get vaccinated, we find that 62% of people who are skeptical of vaccines said that they will forgo COVID-19 vaccination.

To assess this, we measured vaccine skepticism by asking respondents three questions about whether they find vaccines to be safe, effective, and/or important — which is how vaccine skepticism is typically measured. Respondents indicated whether they thought each characteristic described vaccines “quite a bit,” “a moderate amount,” “a little bit,” or “not at all.” We then averaged the score across the three to create a scale of vaccine skepticism.

Nearly one-fifth (19%) of respondents were more vaccine skeptical than not. Among vaccine skeptics, 62% stated that they would not get vaccinated against COVID-19. By contrast, just 15% of those more supportive of vaccines than skeptical said that they would not get the COVID-19 vaccine.

We also asked respondents whether they self-identified as anti-vaxxers, and nearly 16% said they did. For those who identified as anti-vaxxers, 44% said they would not vaccinate against COVID-19, compared with 19% of people who did not identify as anti-vaxxers.

We believe that these findings, although preliminary, suggest that many people who hold anti-vaccine beliefs may jeopardize the effectiveness of a COVID-19 vaccine once it’s available, due to issues of non-compliance. Furthermore, it appears that anti-vaccine sentiment is at least as widespread as it was before the pandemic began.

We caution that a drawback of this study is that it doesn’t directly measure changes in vaccine sentiment over time. However, the levels of anti-vaccine sentiment found in this data are comparable to similar levels of anti-vaccine sentiment in the American public before the pandemic, according to previous studies. Tracking public attitudes toward a COVID-19 vaccine can help public-health agencies better understand who plans to receive the vaccine, and why some people might choose to refuse it.

Kristin Lunz Trujillo is a doctoral candidate in political science at the University of Minnesota; Matt Motta is assistant professor of political science at Oklahoma State University. This article first appeared on The Conversation.