On Wednesday morning, conservation biologists gathered at the Poço das Antas Biological Reserve in Rio de Janeiro state to review newly published maps identifying ‘priority zones’ for yellow fever vaccination among golden lion tamarins. The focus is urgent: since early June, local NGOs have reported multiple virus outbreaks in Brazil’s Atlantic Forest, putting the region’s estimated 4,800 tamarins—80% of the global population—at risk.

The research, led by the Associação Mico-Leão-Dourado and published this week, used GPS collar data and satellite imagery to pinpoint forest fragments where tamarin populations overlap with recent mosquito-borne yellow fever cases. The modeling identified six high-priority zones, covering just 22% of the species’ range but hosting over 60% of known tamarin groups. Field teams are now racing to deploy oral vaccines in these areas, aiming to reach 3,000 individuals by the end of August 2026.

Yellow fever, historically a human health concern, began impacting primate populations in southeastern Brazil in the past five years, with local extinction events recorded in some reserves. While the Ministry of the Environment committed last year to support vaccination campaigns, delivery has lagged; only two of the six zones received full vaccine coverage by July 2026, according to NGO progress reports.

Researchers and SDG 15 advocates warn that the stakes extend beyond biodiversity. Golden lion tamarins are a flagship species for the Atlantic Forest’s restoration—critical for regional climate resilience and carbon storage. With tourist visits to reserves spiking this summer, local officials say the success of this vaccination campaign will influence both conservation outcomes and regional ecotourism revenue through 2026.