That was true (and continues to be true) of COVID testing in the U.S. and other countries. It was true of a lack of protective equipment for frontline health care workers around the world as nations scrambled to secure as many materials as possible. Now, Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization (WHO), has a stark warning for the globe: Don’t let the same thing happen with a COVID vaccine.

“Supply nationalism exacerbated the pandemic and contributed to the total failure of the global supply chain,” he said in remarks to the press. “This is not charity. We have learned the hard way that the fastest way to end this pandemic and to reopen economies is to start by protecting the highest-risk populations everywhere, rather than the entire populations of just some countries.”

To put a finer point on it, he added: “We need to prevent vaccine nationalism.”

But whether or not nations will abide by that ideal is an open question. The United States and various other countries have already been scrambling to secure doses of various coronavirus vaccine candidates, well ahead of any actually gaining approval.

In July, the Trump administration pledged $2.1 billion to secure up to 600 million doses of Sanofi and British drug giant GlaxoSmithKline’s experimental coronavirus vaccine. In August, the U.S. struck another deal for 100 million doses of upstart biotech Moderna’s COVID vaccine candidate; 300 million doses of AstraZeneca and Oxford’s vaccine had been pledged to the U.S.

Doling these out to the masses will require some serious ethical considerations by pharmaceutical companies and national governments, as IDEA Pharma CEO Mike Rea writes for Fortune.

“While we’ve heard that pharma’s normal behavior has been suspended in pursuit of a vaccine for COVID-19, we have already seen rumblings of business as usual in the procurement and pricing of [Gilead’s coronavirus treatment] remdesivir,” he says. “Should the first person to be vaccinated for SARS-CoV-2 be the one with the most exclusive credit card, or the most influential government? Should they be among the most vulnerable or the most critical frontline workers?”

Tedros expressed similar sentiments during his press conference. And a major part of the consideration will be for the nations most in need, frontline health workers, and the highest-risk populations for contracting COVID—decisions that will be informed, in part, by a WHO panel.

“[O]nce a successful vaccine has been identified, WHO’s strategic advisory group will provide recommendations for their appropriate and fair use,” he says. “While there is a wish amongst leaders to protect their own people first, the response to this pandemic has to be collective.”

Whether the world will heed that call is a more complicated issue.