Evolution of the normalized absorbance signal of serum samples from patients diagnosed as positive to Influenza A/H1N1/2009.

<p>(A) Samples from two distinct patients were taken during the first three weeks after the onset of disease. Specific antibody titers more than double their basal value after day 7. (B) Samples from a patient taken at day 21, 100, and 215 after the onset of disease reveal that antibody titters remained high for at least seven months. Patients were diagnosed using RT-PCR protocols (WHO, 2009).