CD40LG and COVID-19: According to the results of Fox and co-workers, in all BM samples (n = 15) collected from COVID-19 positive mothers, IgA against to the full spike protein of the SARS-CoV-2 were present, instead of prepandemic collected samples, while 12 out of 15 samples also contained IgA against the receptor binding domain (RBD) of the SARS-CoV-2 spike protein, mostly being secretory IgA (sIGgA); 67% of samples also showed IgG or IgM anti-RBD [37].