The Next Pandemic Could Emerge from the Americas: Cows, Birds, Humans, and Pigs - The Chain of Reassortment Leading to the "Worst-Case Scenario"

The Brazilian newspaper InfoMoney reported the perspective of Nancy Bellei (UNIFESP), an expert in infectious diseases and virology, stating that "the primary source of risk for a new pandemic now is the Americas, particularly the United States." This is due to the "unusual" spread of the highly pathogenic H5N1 avian flu, which continues to infect not only poultry but also a variety of mammals such as dairy cattle. The U.S. Centers for Disease Control and Prevention (CDC) maintains a level of caution, although it assesses the public risk as "low." In July 2025, emergency measures were concluded, transitioning to regular monitoring, but the number of human infections reported in the U.S. during 2024-25 reached several dozen cases. Meanwhile, according to Fiocruz's Infogripe, more than half of the severe acute respiratory syndrome deaths in 2025 were due to seasonal influenza A, with low vaccination rates potentially acting as "fuel." Additionally, there are risks of reassortment (genetic recombination) through pigs, and the resurgence of diseases like dengue and mpox, presenting a "complex disaster" scenario. On social media, there is a mix of "over-cautious" and "alert fatigue" perspectives, with noticeable concerns from frontline workers and calm analyses based on data. What is needed includes phased vaccinations for occupations at exposure risk, enhanced monitoring of pigs and cattle, expansion of rapid testing, and transparent information dissemination.