A 15-year-old boy from the Amazon indigenous community on Wednesday contracted the novel coronavirus, the first case of the infection among the Yanomami people in Brazil, AFP reported.

Anthropologists and health experts have warned that the epidemic could have a devastating impact on Brazil’s 850,000 indigenous people, whose lifestyles in tribal villages rules out social distancing. Indigenous groups in the Amazon rainforest are known to be vulnerable to imported diseases, as they have been historically isolated from germs against which much of the world has developed immunity.

“We confirmed a case [of the virus] among the Yanomami, which is very worrying,” Health Minister Luiz Henrique Mandetta said at a news conference. “We have to be triply cautious with (indigenous) communities, especially the ones that have very little contact with the outside world.”

Officials said the teenager is being treated in the intensive care unit of a hospital in Boa Vista, the capital of Roraima, the northern Brazilian state where much of the Yanomami reserve is located.

Last week, a 20-year-old from the Kokama ethnic tribe tested positive for the coronavirus. Brazil has now confirmed at least seven coronavirus cases among the indigenous population.

In an address to the nation on Wednesday, President Jair Bolsonaro said that the anti-malaria drug hydroxychloroquine was saving lives of coronavirus patients and should be used in the initial stages of Covid-19. Due to the absence of scientific evidence on its effectiveness and safety, Brazil’s health authorities use it only for critical patients in the hospital.

Confirmed cases of coronavirus in Brazil rose to 15,927 on Wednesday, with the 800 deaths so far.