InfluenCEF Study: Study on the Headache Associated With Influenza Infection

The goal of this observational analytic study with a cohort desing is to evaluate the epidemiology, risk factors and clinical phenotype of headache during Influenza infection. The study will be done in collaboration with the Healthcare Sentinel Network of Castile and Leon (Red Centinela Sanitaria de Castilla y León, RCSCYL) and the National Influenza Center of Valladolid (CNGV). First, the historical data of the VIGIRA network of the 2010-2022 flu seasons will be analyzed, assessing the epidemiology and risk factors of headache during Influenza infection; and second, a study with a case series design with prospective follow-up will be carried out for the incident cases of the 2022-2023 and 2023-2024 Influenza seasons, evaluating the clinical phenotype and the duration of the headache.

Inclusion Criteria:Confirmed diagnosis of influenza virus infection, using molecular techniques (PCR) or antigen test.Age older than 18 years old.Exclusion Criteria:Critical medical situation that makes impossible the clinical interview and evaluation of clinical symptoms.Prior history of dementia or cognitive impairment that makes it difficult to assess patients or describe symptoms.Speech or language impairment, or insufficient comprehension of the Spanish language that makes evaluation difficult.Deceased during the course of the flu infection before they could be tested.Decline to be interviewed.