Fig. 1.

Proportion of samples testing positive for anti-SARS-CoV-2 antibodies. Samples were stratified based on the delay from onset of symptoms. Weak signals, i.e., trace in immunochromatographic test results close to the cut-off value in ELISA, were considered as positive. The proportion of positive tests for each category and for each test and antibody isotype is indicated. For tests combining the detection of two isotypes, the last column indicates positivity for at least one of the two isotypes.