RIO DE JANEIRO — Brazil's virtually unchecked coronavirus outbreak, second worst in the world and growing, is making the country an attractive proving ground for researchers racing to find a vaccine.

A vaccine developed at Oxford University, said by the World Health Organization to be the furthest along of several candidates worldwide, is now being tested on 5,000 volunteers in Rio de Janeiro, São Paulo and an undisclosed site in northeastern Brazil. The Chinese firm Sinovac Biotech will soon begin trials on a separate vaccine in partnership with a Brazilian research institute, and Italian researchers will probably follow with a third. Other immunological firms are also signaling interest in Brazil.

Latin America’s largest country has reported more than 1.4 million cases and 60,000 dead, second in both only to the United States, in an outbreak that has leaped from the coastal cities to the country’s vast interior.

The trials have been closely followed by national news here. Brazilians generally are celebrating the opportunity to contribute to the global search for a vaccine — and looking to capitalize on a potential winner — rather than griping at being used as international guinea pigs.

The Oxford vaccine is based on a weak and non-replicating strain of the common cold. Preliminary results in the trials are due as soon as October.

Brazilian scientists say the country’s scientific infrastructure and strong record on inoculations also make the country attractive.

“This normally takes at least a decade, and we are trying to do this in a year,” said Marco Krieger, vice president for innovation and research at the Oswaldo Cruz Foundation, a research institute in Rio. “This is a global effort, and without doubt Brazil will be contributing to that effort.”

All of the trials to be conducted in Brazil are in Phase 3 of development, having been tested already on animals and on smaller groups of people. Phase 3 is when tests are performed on larger groups.

The Brazilian government is in talks with AstraZeneca to produce millions of doses of the Oxford vaccine. It has enlisted the Oswaldo Cruz Foundation in the effort. There’s no guarantee the vaccine will be effective and safe, but if it is, Brazil will have an immediate stockpile to begin inoculating front-line health professionals and vulnerable groups.

“Our first goal is that we have access,” interim health minister Eduardo Pazuello said. “It’s so we can participate and are free to make the vaccine, not just buy it. In Latin America, only Brazil has this capacity.”

Brazil’s eager participation in the vaccine trials could be seen as being at odds with how it has otherwise handled the pandemic. President Jair Bolsonaro has called for a national policy of doing nothing. The right-wing populist has repeatedly dismissed the danger of the coronavirus and has had little to say to or about its victims. Last week, he called Brazil’s response, one of the loosest in the world, “a little bit exaggerated.”

The inaction has placed Brazil on a path few countries have traveled. Each day brings tens of thousands of new diagnoses. The virus is reaching deeper into remote regions, where hospitals are ill-equipped to handle the deluge of patients.

“The vaccine will be the key,” said Lily Yin Weckx, a Brazilian epidemiologist helping to lead the Oxford study. “If you can’t treat the disease, what you have to do is prevent it, like many other diseases have been controlled by vaccines.”

Dozens of vaccines are in development around the world. Weckx said each could end up being useful. Some might be more effective in specific populations, such as older people. Others could last for longer or shorter periods of time. It’s important, she said, to pursue them all.

“Likely we are going to have many approved vaccines, and all of them are going to be useful in prevention,” she said.