Inactivated SARS-CoV-2 Variant Omicron, Lineage BA.2.75.5 (USA/NY-Wadsworth-22037154-01/2022)

Coronavirus disease is caused by a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Some of these viruses are considered or have been reported as being of critical importance due to their increased infectivity, increased pathogenicity, or the risk of reduced vaccination effectiveness against the pathogen. These variants have been implicated in the spread of the COVID-19 emerging infectious disease. In October 2022, the World Health Organization designated only the Omicron variant as a circulating variant of concern. The low number of infections in the early stages of an epidemic (and especially in the later stages) means that the genetic code is less likely to mutate, and therefore the likelihood of different variants emerging is also lower. Due to the rarity of the sequence, the observed changes in the S protein gene within the RBD sequence of the enzyme that interacts with ACE2 are also uncommon. As random substitutions in SARS-CoV-2''s genes evolve over time, those biotypes that have proven to be highly transmissible have also evolved in the environment.

The Omicron virus was first discovered in South Africa in November 2021 and is far more transmissible than previous VOCs. Furthermore, it possesses more genetic variations than previous variants, enabling it to evade both naturally evolved immune protection and vaccination. Taken together, these characteristics have enabled the omicron virus to spread rapidly across the globe, leading to a surge in infections far exceeding the levels observed in the early stages of the outbreak. Since the emergence of the omicron virus, the previously dominant subvariant, BA.1, has been rapidly replaced by subvariants BA.2 and BA.2.12.1, which are more contagious but appear unable to evade vaccine-induced protection. However, subvariants BA.4 and BA.5 have surpassed these subvariants to become the most prevalent genotypes globally. Numerous preclinical studies of BA.4 and BA.5 have found that they are associated with reduced spontaneous SARS-CoV-2 disease and immune neutralization activity compared to previous omicron subvariants.