Fig. 2. Changes in the levels of antibodies reactive to S1 SARS-CoV-2 in human milk from five mothers with previous viral symptoms and four mothers without symptoms across time during the COVID-19 pandemic.

A–C S1-reactive SIgA/IgA, B–D S1-reactive SIgM/IgM, C–F S1-reactive IgG, A–C mothers in viral symptom groups, and D–F mothers in the no-symptom group. Human milk samples were collected once per month from March 2020 to June 2020 for each mother (four different time points). M1–M5 are mothers in the viral symptom group, while M6–M9 are mothers in the no-symptom group.