The SARS-CoV-2 virus is rapidly evolving via mutagenesis, lengthening
the pandemic, and threatening the public health. Until August 2021, 12
variants of SARS-CoV-2 named as variants of concern (VOC; Alpha to
Delta) or variants of interest (VOI; Epsilon to Mu), with significant
impact on transmissibility, morbidity, possible reinfection and
mortality, have been identified. The VOC Delta (B.1.617.2) of Indian
origin is now the dominant and the most contagious variant worldwide as
it provokes a strong binding to the human ACE2 receptor, increases
transmissibility and manifests considerable immune escape strategies
after natural infection or vaccination. Although the development and
administration of SARS-CoV-2 vaccines, based on different technologies
(mRNA, adenovirus carrier, recombinant protein, etc.), are very
promising for the control of the pandemic, their effectiveness and
neutralizing activity against VOCs varies significantly. In this review,
we describe the most significant circulating variants of SARS-CoV-2, and
the known effectiveness of currently available vaccines against them