(Bloomberg) -- After failing to broker a deal with Pfizer Inc., Argentine President Alberto Fernandez was so desperate to secure Covid-19 vaccines that he rushed a passenger plane to Moscow in December to bring in Sputnik V doses before his own regulators had a chance to approve the shot.

The approval for emergency use arrived hours before the Aerolineas Argentina flight carrying 300,000 of the Russian shots landed at the Buenos Aires airport, to much media fanfare.

Throughout the developing world, countries like Argentina have been squeezed out by richer nations in the race to secure vaccines produced by Western companies such as Pfizer and Moderna Inc. Across most of Africa and large swaths of Latin America, south Asia and southeast Asia, little or no vaccine has been distributed, according to Bloomberg’s Vaccine Tracker.

As a candidate and then president, Joe Biden repudiated Donald Trump’s “America First” approach to the world. But when it comes to vaccines, Biden is basically following his predecessor’s practice of making sure Americans are fully protected before sharing the doses around the world.

Seeing an opportunity to exert “soft power,” Russia and China have stepped into that breach, doling out doses to countries from Chile to the Philippines as a way to curry favor. While the U.S. makes promises about the future, Russia and China are delivering, albeit modestly, now.

“The U.S. hasn’t made a diplomatic gesture that is as recognizable as what Russia and China are doing by having their actual vaccines arrive,” said Annie Pforzheimer, a retired U.S. diplomat who wrote a report on the U.S. response to the pandemic in Latin America.

Some critics, including Argentina’s president, are more blunt, accusing wealthy nations of hoarding at their expense.

Enter Vladimir Putin. Russia’s president makes discussing access to its Sputnik vaccine -- which has been found to be highly effective -- a key part of his calls with foreign leaders. Russia has vowed to deliver 700 million doses of the vaccine abroad this year, although production so far hasn’t matched that pace.

Then there’s China. In trips to Myanmar and Brunei in recent months, Chinese Foreign Minister Wang Yi has pledged help with vaccine distribution while calling for greater collaboration on the commercial and infrastructure projects of President Xi Jinping’s Belt and Road Initiative. China’s state-owned media have touted its Sinovac as highly effective, despite concerns over its promised safety and level of protection. Hesitancy about the vaccine’s potential side effects has increased in mainland China and Hong Kong.

The U.S. has grown alarmed at those efforts and is emphasizing its $4 billion in support for Covax, an initiative backed by the World Health Organization, the vaccine alliance Gavi and the Coalition for Epidemic Preparedness Innovations that offers vaccines at low cost to developing countries.

“We are concerned about the use or the attempted use of vaccines as a means of diplomacy by Russia and China,” Jen Psaki, the White House press secretary, told reporters this month.

Covax’s goal is to help build manufacturing capabilities and place orders in advance so it can distribute as many as 2 billion doses “fairly” by the end of this year. Its aims to help end the most acute phase of the pandemic and get 20% of a target country’s population vaccinated. But it still has to compete with countries like the U.S. and U.K. to get those deals signed.

There’s a huge gap to fill. As of last week, 80% of the world’s vaccine supply had gone to just 10 wealthy countries, according to Robbie Silverman, senior corporate advocacy manager for Oxfam America.

Meanwhile, President Biden has ordered enough vaccine doses to fully inoculate every American adult twice, with the administration saying it needs to be prepared for every contingency after more than 529,000 citizens died from the coronavirus over the past year, more than any other nation.

“We’re going to start off making sure Americans are taken care of, first, but we’re then going to try to help the rest of the world,” Biden said at the White House on Wednesday. Pledging to work with Covax, he said, “We’re not going to be ultimately safe until the world is safe.”

The rest of the world doesn’t want to wait any longer. So even though citizens in developing countries are sometimes skeptical about the efficacy of non-Western vaccines -- for which clinical trial data is less readily available -- their leaders have had little choice but to seek Russian and Chinese shots.

Pfizer, which developed its vaccine with Germany’s BioNTech SE, has been criticized for making what some countries call excessive indemnity demands in Latin America, though it has recently been signing more deals. Before turning to Russia, Argentina’s former health minister said in December that Pfizer’s terms for procuring its vaccine were “unacceptable.”

The company defended its position.

“Pfizer and BioNTech are firmly committed to working with governments to ensure equitable and affordable access to our Covid-19 vaccine for people around the world,” Pfizer spokeswoman Sharon Castillo wrote in response to questions. “In markets that do not have the legal or legislative protections that are available in the United States, we work with governments to find mutually agreeable solutions, including contractual indemnity clauses.”

Castillo said Pfizer has completed supply agreements with eight countries in Latin America -- Chile, Colombia, Costa Rica, Ecuador, Mexico, Panama, Peru and Uruguay -- and “negotiations are ongoing with several other governments.”

The U.S. role in vaccine donation may shift by the summer. Production is ramping up, and Biden’s announcement that the U.S. will have enough supply by the end of May to vaccinate all American adults means that the picture could change. At the same time, China and Russia are nowhere close to vaccinating their entire populations.

“Starting in June, we will have access to hundreds of millions of vaccine shots and may well be by the end of the year the largest source of supply,” said Krishna Udayakumar, the director of the Duke Global Health Innovation Center. “The U.S. will play a strong leadership role in the global response including access to vaccines.”

Public health and humanitarian experts argue that failing to vaccinate other parts of the world hurts America’s own interests. There’s a downside to the global economy from keeping other countries closed, there’s the risk that the virus could mutate in other countries and there’s the diplomatic optics.

The United Nations, Oxfam and other groups are calling for rich countries to share their intellectual property so that the vaccines can be manufactured around the world. Additionally, they are urging continued investment in manufacturing capacity and more licensing deals.

“There is a vast chasm of inequality that is concerning on multiple grounds,” said Silverman of Oxfam. “It leaves a vacuum for other countries to come in and provide doses to promote their national interest.”

Western leaders insist that as Covax picks up strength, perceptions will shift. Several countries, from Ghana to the Philippines, have started receiving doses in recent weeks. The U.S. and its allies are betting those countries will soon notice a major impact from the investment in Covax.

“The global effort to distribute safe and effective coronavirus vaccines is not a competition,” Barbara Woodward, the U.K. ambassador to the UN, told Bloomberg News. “We need to work together, and the Covax facility is the best way for countries to cooperate to ensure equitable access to vaccines.”

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