A new initiative will bring more vaccines to Latin America and the Caribbean.

The Pan American Health Organization plans to distribute millions of coronavirus vaccines in Latin America and the Caribbean starting this fall, an initiative that amounts to a tacit recognition that the United Nations-backed Covax program will not come close to providing the immunizations that the developing world needs.

The organization, which is part of the World Health Organization, intends to buy “tens of millions” of vaccine doses and start delivering them in October, its director, Dr. Carissa Etienne, said on Wednesday.

“It is an initiative that will benefit every country in the region but especially those that lack the resources and the negotiating power to secure the doses that they need to protect their people,” said Dr. Etienne.

So far, more than 20 countries have expressed interest in joining the program, she said. The latest data indicates about 20 percent of people in Latin America and the Caribbean have been fully immunized against Covid-19, with some countries reporting vaccination rates of less than 5 percent.

Covax remains far from its initial target of vaccinating at least 20 percent of the people in the world’s poorer countries, but even that would not be enough to control transmission of the virus, particularly as the highly contagious Delta variant starts to circulate in the region.

Dr. Jarbas Barbosa, assistant director at the Pan American Health Organization, said that to get the virus under control, “countries need to go further than 20 percent and it is not clear if Covax will offer more vaccines after this 20 percent.” He said negotiations to obtain the vaccines have begun with producers.

The officials did not provide details about how the organization would succeed where Covax has failed, but they said that the organization had decades of experience buying and distributing vaccines on behalf of countries in the region. The countries will have to pay for the vaccines, while Covax has mostly distributed them free to poorer countries.

“There is no path to recovery for any country while its neighbors remain vulnerable and while variants circulate and multiply,” Dr. Etienne said. “We must banish the idea that vaccine inequity is the problem of some countries and not others.”

Covid cases and deaths are rising in Central America and the Caribbean while the “trends are more promising in South America,” where there has been an overall decline in cases and deaths, Dr. Etienne said.

“There is clear evidence that wherever vaccines are available, they limit severe illness and save lives,” she said. “And that is why increasing access to vaccines remains our top priority. The disparity in who can access vaccines and who cannot is unacceptable.”