The SARS-CoV-2 mRNA vaccine breakthrough infection phenotype includes significant symptoms, live virus shedding, and viral genetic diversity.

Little is known about SARS-CoV-2 'vaccine-breakthrough' infections (VBI). Here we characterize 24 VBI in predominantly young healthy persons. While none required hospitalization, a proportion endorsed severe symptoms and shed live virus as high as 4.13 x 10 3 PFU/mL. Infecting genotypes included both variant-of-concern (VOC) and non-VOC strains.