Only patients with borderline or positive results in the corresponding tests were used for calculation. In NT, one patient (3.2%) lost antibodies, two (6.5%) developed higher, more stable IgG titers, the antibody titers of 28 patients (90.3%) stayed constant during the first five months post infection.

Figure 1: The median titer of s ymptomatic patients was two levels higher than those of asymptomatic patients.

Figure 2: Development of neutralizing antibodies goes along with disease severity. Neutralization activity is more pronounced in patients with more severe infections. Moderate and severe courses of disease led to neutralizing antibodies in 100% of the patients, whereas 33% and 20% of persons with an asymptomatic course of infection did not constantly develop neutralizing antibodies.