Veterinarian Suelen Sanches Ferreira, left, inoculates a pregnant golden lion tamarin with a yellow fever vaccine, in a lab run by the nonprofit Golden Lion Tamarin Association, in the Atlantic Forest region of Silva Jardim, Rio de Janeiro state, Brazil, Monday, July 11, 2022. Conservationists who had toiled for decades to protect the monkeys were sharply divided over whether to inoculate the tamarins. Some were hopeful, at first, the virus wouldn’t impact the monkeys; others worried that any kind of novel intervention would be too risky. (AP Photo/Bruna Prado) 
A golden lion tamarin is handled by researchers after it was vaccinated against yellow fever in a lab run by the nonprofit Golden Lion Tamarin Association in the Atlantic Forest region of Silva Jardim, Rio de Janeiro state, Brazil, Monday, July 11, 2022. Scientists in Brazil adapted a human yellow-fever vaccine to inoculate these endangered monkeys after yellow fever began to spread among the human population in Brazil in 2016, which quickly killed a third of the highly vulnerable tamarins, the majority of them in just a few months. (AP Photo/Bruna Prado) 
Research assistant Ademilson de Oliveira uses a telemetry device to locate golden lion tamarins in the Atlantic Forest region of Silva Jardim, Rio de Janeiro state, Brazil, Friday, July 8, 2022. Many golden lion tamarins are descendants of animals carefully released in 1984, in cooperation with local landowners. That effort and subsequent campaigns to replant and connect parcels of rainforest, has seen the population of tamarins slowly recover. (AP Photo/Bruna Prado) 
A golden lion tamarin sits in a tree in the Atlantic Forest region of Silva Jardim, Rio de Janeiro state, Brazil, Friday, July 8, 2022. A campaign to vaccinate these endangered monkeys in Brazil against yellow fever may help save them from extinction. (AP Photo/Bruna Prado)
Race to vaccinate rare wild monkeys gives hope for survival
