throat swab RNA concentrations seemed to be already on the decline at
the time of first presentation. Sputum RNA concentrations declined more slowly, with a peak
during the first week of symptoms in three of eight patients. Stool RNA concentrations were
also high. Courses of viral RNA concentration in stool seemed to reflect courses in sputum in
many cases (e.g., Figure 2 A, B, C). In only one case, independent replication in the
intestinal tract seemed obvious from the course of stool RNA excretion (Figure 2 D).
Whereas symptoms mostly waned until the end of the first week (Table 2), viral RNA
remained detectable in throat swabs well into the second week. Stool and sputum samples
remained RNA-positive over even longer periods, in spite of full resolution of symptoms.
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All cases had comparatively mild courses (Table 2). The two patients who showed some
signs of pneumonia were the only cases where sputum viral loads showed a late and high
peak around day 10/11, whereas sputum viral loads were on the decline by this time in all
other patients (Figure 2 F,G).
Seroconversion was detected by IgG and IgM immunofluorescence using cells expressing
the spike protein of SARS-CoV-2 and a virus neutralization assay using SARS-CoV-2 (Table
3). In early sera, taken between day 3 and 6, none of the patients showed detectable
antibody. The patients monitored long enough to yield a serum sample after two weeks all
showed neutralizing antibodies, the titer levels of which did not suggest any correlation with
clinical courses. Of note, case #4, with the lowest virus neutralization titer at end of week 2,
seemed to shed virus from stool over prolonged time (Figure 2 D). Results on differential
recombinant immunofluorescence assay indicated no significant rise in titer against the four
endemic human Coronaviruses (Table S1).