On 30 September 2026, Brazil notified PAHO/WHO of a laboratory-confirmed human infection with an influenza A(H1N1)v virus in an adult woman, with pre-existing chronic conditions, residing in the state of Santa Catarina. She developed symptoms of influenza-like illness on 16 July 2026 and sought medical attention on 20 July. Her husband and three adult children, who live in the same household, also experienced symptoms of an influenza-like illness; at that time, all were diagnosed, based solely on clinical examination, with a viral infection and received treatment. The woman, however, did not recover. On 27 July, the patient was hospitalized due to worsening respiratory symptoms. She received treatment, including the antiviral oseltamivir, and required intensive care, including ventilatory support. Despite intensive care, the patient passed away on 28 August. A nasopharyngeal sample, collected on 29 July, tested positive for influenza A on 30 July and was subsequently subtyped as influenza A(H1N1) on 31 July. The sample was sent to the reference laboratory for respiratory viruses at the Oswaldo Cruz Institute (IOC/Fiocruz) in Rio de Janeiro for further characterization. On 4 September, genomic analysis identified an influenza A(H1N1)v virus. According to information gathered during an epidemiological investigation conducted by municipal and state teams between 5 and 9 September, the patient had no history of travel or direct contact with swine. However, a possible indirect exposure to swine was identified through a neighbor who raises these animals for personal consumption. Since 2015, twelve cases of human infection with swine-origin virus variants, including this one, have been detected within Brazil’s respiratory virus surveillance workflow.