When it came to shifting the United States’ pandemic posturing, Joe Biden wasted no time. Within hours of his inauguration, the president retracted the previous administration’s decision to withdraw the U.S. from the World Health Organization and signed executive orders mandating mask wearing on federal property and public transportation.

The next day, his chief medical adviser, Anthony Fauci, confirmed that the U.S. would also be supporting COVAX, the international initiative aimed at equalizing vaccine distribution around the world.

The moves were widely received as a necessary corrective to American isolationism under Donald Trump. With Biden in charge, the U.S. appeared to finally be resuming its role as a global leader—one that, as the president pledged in his inaugural address, would “lead not merely by the example of our power, but by the power of our example.”

The reality, however, has proved far less poetic: Within a week of the WHO and COVAX announcements, the Biden administration also said that it hoped to ramp up the U.S.’s vaccine rollout to 1.5 million vaccinations a day—an effort that will be buoyed by the purchase of a further 200 million doses of the Pfizer-BioNTech and Moderna vaccines. The new deals put the country’s projected vaccine supply at 1.2 billion doses, according to the Duke University Global Health Innovation Center’s vaccine-procurement tracker—enough to inoculate the American population twice over.

Far from supporting more equitable vaccine distribution around the world, the U.S. under Biden is continuing to undermine it, to the detriment of poorer nations, as well as itself.

To be fair to the U.S., it’s not alone. High-income countries, virtually all of which have signed on to COVAX, have secured nearly 60 percent of the 7.2 billion vaccine doses purchased so far, according to Duke, despite representing just 16 percent of the global population. Though many of these countries have reserved enough doses to inoculate their population several times over, that hasn’t prevented them from sparring over who gets the doses first.

The European Union, in an apparent bid to make up for the shortfall in its own vaccine supply, even went so far as to announce export controls on doses leaving the bloc—a decision that was quickly reversed following an uproar.

While nothing is inherently wrong with wealthy countries wanting to secure enough supply to protect their population, their actions become an issue when they prevent low- and middle-income countries from doing the same.

Early on in the pandemic, experts warned that vaccine nationalism—in which countries prioritize their own domestic needs at the expense of everyone else—would hinder global economic recovery and prolong the public-health crisis.

Nearly a year on, those concerns have largely been borne out: High-income countries that bought themselves to the front of the vaccine line have all but cleared the shelves, leaving little in the way of short-term supply for the world’s poorest countries, the large majority of which haven’t received any vaccine doses.

At the same time, uncontrolled outbreaks in Brazil, Britain, and South Africa have spurred new, more transmissible variants of the coronavirus that have since spread around the world, proving that if the virus is left endemic anywhere, it can still pose a threat everywhere.

Until recently, the U.S. didn’t feign to care about equal distribution. As with most of its policies, the Trump administration opted for an “America First” approach to public health, prioritizing domestic vaccination efforts over multilateral initiatives. In keeping with this approach, one of Trump’s final acts as president was an attempt to scrap $4 billion in funding earmarked for Gavi—one of the organizations leading COVAX alongside the WHO—from Congress’s recent spending bill. That request was ultimately rebuffed.

Though Biden has sought to reverse many of Trump’s policies, the U.S.’s commitment to prioritizing its own vaccine procurement remains unchanged. From a global-distribution standpoint, the U.S. joining COVAX doesn’t change the fact that most wealthy countries have already reserved the lion’s share of the world’s available vaccine supply.

“We’re sort of past trying to say, ‘Okay rich countries, stop buying doses,’” Andrea Taylor, the assistant director of programs at Duke’s Global Health Innovation Center, told me. As far as equitable access is concerned, “that ship has sailed.”

This doesn’t mean that nothing can be done to rectify the situation. Wealthy countries could simply contribute more funding to COVAX, which would give the initiative the buying power it needs to reserve a fair share of doses for the countries relying on it. The initiative announced this week that it will aim to distribute more than 300 million doses—enough to cover approximately 3 percent of receiving countries’ populations—by the end of June.

Though COVAX has raised more than $6 billion so far, a Gavi spokesperson told me that it will need a further $2 billion to hit its 2021 targets. Still, as Taylor noted, most of the priority manufacturing capacity for this year has already been reserved, meaning that even if COVAX were to secure more doses, companies wouldn’t necessarily have the means to produce them all immediately. Indeed, current models project that it will take years before there are enough doses to meet global demand.

The other, perhaps more realistic option is for high-income countries to donate doses directly to low-income ones. Under this solution, which has already been championed by Norway, donations would occur in tandem with richer countries’ domestic vaccination programs, ensuring that poorer states aren’t put in the position of having to wait until the world’s wealthiest populations are vaccinated before they can receive lifesaving supplies.

The proposal has been supported by the WHO, albeit with limited take-up: Canada, which has secured more than enough doses to vaccinate its population, has committed to sharing its excess doses only after its population has been inoculated; Britain, which has also secured well over the number of doses needed to vaccinate its population, has suggested that it too would consider donating its extra doses, but said it’s “a bit too early” to specify how and when that would occur. While both countries’ leaders have extolled multilateral efforts to ensure more equitable distribution around the world, neither has been willing to commit to it in practice.

Politically, this is a tough sell for any world leader—not least for Biden, who campaigned on the promise of delivering the U.S. from a public-health crisis that is projected to claim more than half a million American lives. But there are compelling reasons for why his government should commit to sharing its vaccine supply—if not for the sake of poorer countries, then for its own people.

The first is economic: Though it’s projected to cost $25 billion to supply enough vaccines for low-income countries, modeling by the Rand Corporation projects that unequal distribution would cost the global economy $1.2 trillion a year in GDP, owing to the delayed recovery of key sectors such as the tourism and retail industries.

Another study, by the International Chamber of Commerce, offers an even more dire assessment, projecting that the global economy stands to lose as much as $9.2 trillion unless equitable access is assured.

The second, perhaps more significant reason has to do with public health: The emergence of new variants has demonstrated the coronavirus’s capacity to evolve and mutate into more transmissible forms. Ashish Jha, the dean of Brown University’s School of Public Health, warned in a series of tweets that if coronavirus outbreaks are left uncontrolled anywhere, they could jeopardize the safety of people everywhere, including countries that are widely vaccinated.

“We might see [a] rise of variants that eventually escape the vaccines and make everyone vulnerable again,” Jha wrote. “It’s the nightmare scenario of the never-ending pandemic.”

The Biden administration has discussed ensuring more equitable distribution, Ezekiel Emanuel, an oncologist, bioethicist, and a member of President Biden’s Transition COVID-19 Advisory Board, told me.

It’s something that Emanuel has thought a lot about too. In September, he co-wrote a report advocating for an ethical framework for global vaccine allocation, in which vaccine distribution would be based not on the size of a country’s population (as is currently the case under COVAX), but with the primary focus of reducing the mortality and economic impact of the pandemic.

“Countries have a good reason to try and get to herd immunity in their own countries and that’s a very important consideration,” he said, adding that “once they get to herd immunity, there is a very good rationale for the next doses to go to countries where they can save lives.”

Though Emanuel said it’s unrealistic to expect wealthy countries to follow Norway’s lead (“It’s a lot easier when you’re a [small] country”), he noted that the rise of new variants gives every country a stake in more equitable distribution. “That gives us a big interest in making sure the whole world is addressed,” he said. “This is more than just our borders.”

My colleague Tom McTague has noted how Britain could still rewrite its pandemic story. The same could be true for the U.S. and other wealthy countries—but only if they take the steps necessary to ensure that the pandemic ends beyond their own borders. Until they do, the prevailing narrative will be one of an avoidable nightmare from which even the most vaccinated countries can’t wake up.