ABSTRACT
The emergence of SARS-CoV-2 variants of concern (VOC) has raised questions regarding the extent of protection of currently implemented vaccines. Ten "vaccination breakthrough" infections were identified in Alachua County, Florida, among individuals fully vaccinated with the BNT162b2 mRNA vaccine as a result of social or household transmission. Eight individuals presented mild symptoms in the absence of infection with other common respiratory viruses, confirmed using viral genetic sequencing. SARS-CoV-2 genomes were successfully generated for five of the vaccine breakthroughs and 399 individuals in the surrounding area and were included for reference-based phylogenetic investigation. These five individuals were characterized by infection with both VOCs and low-frequency variants present within the surrounding population. Mutations in the Spike protein were consistent with their respective circulating lineages, with the exception of a viable, low-frequency (approximately 1%) B.1.1.7 mutation, which we describe as a mutation of potential concern. The findings indicate that in cases of limited vaccine protection, infection is not restricted to VOCs or high-risk settings, highlighting the critical need for continued testing and monitoring of infection among individuals regardless of vaccination status.