Influence of the course of disease on neutralizing antibodies:
The median neutralizing antibody titer of symptomatic patients was two levels higher than in asymptomatic patients (n = 31 versus 3 patients;Figure 1 ). However, there was no statistically significant correlation between the individual titers and the severity of infection (k = -0.09).
Our data also reveal a relation between the severity of infection and neutralizing activity by ELNA (3 and 31/34; p = 0.07).
Moderate or severe SARS-CoV-2 infections led to the development of neutralizing antibodies significantly more frequently than in asymptomatic or mild infections (p = 0.03). There was no significant difference in neutralization activities between asymptomatic and mild courses of disease (p = 0.17). Interestingly, 60% of the patients who suffered severe infections (3/5), developed low neutralizing antibodies (Figure 2 ).