In recent decades, dozens of countries across the world have seen cases of poultry and wild birds falling sick with influenza A H5N8, a highly pathogenic avian influenza virus (AIV). The subtype of flu was not generally associated with human infections, but that changed in February 2021 when seven poultry farm workers in southern Russia became the first documented human cases of H5N8 bird flu. Writing in Science, scientists from the Chinese Center for Disease Control and Prevention and Shandong First Medical University warn that H5N8 has demonstrated that it can leap from species to species and holds the potential to erupt into a “disastrous pandemic".