The main objective is to estimate the annual symptomatic incidence of Bordetella pertussis and RSV infections in patients aged 18 years and over with asthma, which will be identified by PCR, for Bordetella pertussis and by PCR for RSV performed at a specific timepoint from onset of symptoms for each symptomatic Acute Respiratory Infection (ARI). A multicentre prospective cohort study will be undertaken in Spain. Thirty-five centres from different autonomous communities in Spain will participate in the study. Participants will be asked to report to the investigator if they experience an asthma exacerbation or symptoms of acute respiratory infection with 2 years follow up