Figure 1. Flowchart of measurements performed in the study population
EGEA: Epidemiological study on the Genetics and Environment of Asthma; IgG: Immunoglobulin G. EGEA1: baseline survey (1991-95). EGEA2: first follow-up of the EGEA participants (2003-07), about 12.5 years after EGEA1. Measurements for virus-specific IgG levels were performed by microarray technology. Unvalidated IgG assessment corresponds to samples excluded due to the lack of sufficient sample volume.