Brazil’s upcoming fire season and drought are likely to complicate Covid cases.

Patients were treated in the coronavirus wing of a hospital in Tefé, a remote municipality in Amazonas, Brazil, last year.Credit…Tyler Hicks/The New York Times

RIO DE JANEIRO — Scientists are projecting another bad fire season in the Amazon, one that could further complicate Brazil’s struggle with one of the world’s worst coronavirus outbreaks.

Widespread Covid devastated the Indigenous people living along the Amazon River in 2020, as fires — usually set by farmers or ranchers seeking more land — devastated the Amazon region.

“The smoke suffocated our villages last year,” said Takumã Kuikuro, a filmmaker who lives in the Alto Xingu region, one of Brazil’s most deforested. “People were falling ill. They couldn’t breathe. And it came as we were already dealing with a pandemic.”

Brazil is now suffering its worst drought in at least 91 years, adding to the likelihood that any fires will spread uncontrolled. Burning in the Amazon has surged under Brazil’s president, Jair Bolsonaro, who claims environmental protections get in the way of economic growth.

Across the country on Saturday, Reuters reported, thousands of people protested the pandemic response by Mr. Bolsonaro, who has dismissed the danger posed by the virus despite contracting it himself last year. The protests came as Brazil surpassed 500,000 known deaths from the virus, a toll second only to that of the United States.

Health experts warn that the smoke and ash that typically blanket the Amazon from June to September could further sicken those fighting Covid or recovering from it. According to Dr. Aljerry Rêgo, a professor and director of a Covid facility in the Amazon state of Amapá, results from “very initial studies” suggest that the smoke can aggravate Covid and increase the risk of death.

He pointed to one clear danger: “The particles from burning biomass enter the lung cavities,” causing “an intense inflammatory response, which comes on top of Covid.”

The smoke could also sicken those who have already recovered from Covid, he said. “I’ve seen a lot of patients with what we call post-Covid syndrome,” Dr. Rêgo said. “Fatigue, this constant shortness of breath, even months after recovering.”

Years of breathing in smoke and ash could be making Brazilians in the Amazon more vulnerable. “Their lungs are often compromised already,” Dr. Rêgo said. “And if they get Covid, they will likely have more lingering effects in the future. It could be a chronic respiratory issue or a higher risk of lung damage.