On April 1, 2024, the CDC confirmed a positive human case of influenza A(H5N1) virus in the United States. The patient showed symptoms on March 27 and had been exposed to dairy cattle infected with the virus. This marks the second confirmed human case of influenza A(H5N1) in the United States and the first known case of human infection from contact with an infected mammal. Human infections with avian influenza A viruses, including A(H5N1) viruses, are uncommon but have occurred sporadically worldwide. The CDC has recommendations for clinicians on monitoring, testing, and antiviral treatment for patients with suspected or confirmed avian influenza A virus infections.