In more than 50 countries, most of them wealthy, coronavirus vaccination efforts are well underway, with some 20 million doses already distributed in the United States alone. But most poorer nations have yet to even begin.

World Health Organization officials said last week that the West African nation of Guinea is the only low-income country of 29 to begin vaccinating. And those efforts have been limited in scope — just 55 people out of the population of more than 12 million have received doses so far.

The initiative, using the Russia-backed Sputnik V vaccine, began Dec. 30 as part of a pilot program carried out on an “experimental basis,” Sakoba Keita, director general of Guinea’s National Health Security Agency, told The Washington Post.

The Russian government proposed the idea, in a “climate of good bilateral relations,” and Guinea accepted, Keita said. Most of the initial vaccinations went to government officials: President Alpha Condé, 82, received a shot in early January.

“We intend to initiate the first real campaign by the end of this first quarter,” Keita said, referring to a wider effort, likely using the Sputnik V vaccine and others procured separately.

“At the moment I cannot provide an exact date because we have not had any announcement of the supply of the first batch of vaccines, which could come to Guinea from any of our suppliers,” he said. “Negotiations are ongoing.”

The unusual arrangement, under which the country has received limited Sputnik V doses, appeared to be the result of close ties between Condé and Russian President Vladimir Putin. Russian business interests connected to the mining of bauxite, a key ingredient in aluminum production, has led Moscow to rekindle its Soviet-era relationship with Conakry, Guinea’s capital.

The slow-to-static pace of vaccinations in low-income countries such as Guinea, which has a gross domestic product per capita of less than $1,000 per year, has been condemned by public health experts, who say that the hoarding of vaccine doses by wealthier nations could extend the pandemic.

“We now face the real danger that even as vaccines bring hope to some, they become another brick in the wall of inequality between the worlds of the world’s haves and have-nots,” WHO Director General Tedros Adhanom Ghebreyesus said at a briefing last week.

Thomas J. Bollyky, a senior fellow at the Council on Foreign Relations, said that although the trend was “depressing and disheartening,” it had been evident for months that wealthy nations had been buying up most of the supply of vaccines.

“I can’t say it’s surprising,” said Bollyky. “In every previous pandemic where we have our global health crisis, where there has been limited supplies of medical intervention, wealthy nations have hoarded.”

Ranu S. Dhillon, an infectious-disease expert at Harvard Medical School, said he was concerned that allowing the virus to spread widely in countries without the means to procure vaccines could allow more variants to emerge, against which vaccines could be less effective.

“It’s a matter of luck, but I think there’s a high likelihood that [a variant] would make its way to Conakry, from Conakry to elsewhere, and then eventually circulate in other parts of the world,” he said.

Bollyky voiced a similar concern. Vaccine inequality “absolutely prolongs the pandemic, but it also creates health risks for high-income nations as well,” he said. “As we’ve seen, this is a virus. It mutates.”

Although Covax, an international effort to source and distribute vaccines backed by the WHO, had hoped to alleviate the inequities by pooling resources to preorder vaccines, the initiative had struggled with funding and found wealthy nations snapped up much of the global supply of vaccines.

Matshidiso Moeti, the WHO’s regional director for Africa, said last week that it hoped the first Covax vaccine doses would reach Africa in March.

So far, the only African country to begin a nationwide vaccination program is the Seychelles, a middle-income island nation with a population of fewer than 100,000. Morocco is due to begin vaccinations this week with the AstraZeneca-developed vaccine after receiving 2 million doses.

Keita said that Guinea was in negotiations with four suppliers of vaccines: Pfizer, AstraZeneca, Sputnik V and the China-backed company Sinopharm. Negotiations with Sputnik V were furthest along, with 1.6 million doses expected for 2021. Pfizer doses would be procured through the Covax program, Keita said.

Unlike many of their peers, the vaccines developed in Russia and China have not released full testing data, leading to skepticism among some public health officials.

Guinea, along with many of its West African neighbors, has been spared from a large-scale coronavirus outbreak, with more than 14,000 cases and 81 deaths, according to government data.

The country was one of the epicenters of an Ebola outbreak in 2014 that killed more than 2,500 people.

Dhillon, who advised the president of Guinea during the Ebola outbreak, said that both Guinean public health officials such as Keita and the general public had experience with a pandemic, which probably proved useful.