Anomalies in regional and chronological distributions of Omicron BA.1.1 lineage in the United States

Abstract

This study compares the collection dates and locations of the Omicron BA.1 lineage and other major SARS-CoV-2 mutants registered in NCBI GenBank and provides a detailed analysis of the emergence patterns of pure reverse mutants, which contain only reverse mutations and no other mutations in the surface glycoprotein. The results indicate that Omicron BA.1.1 and its pure reverse mutants were widely distributed throughout the United States from the early days of their emergence, showing a statistically significant difference compared to other major variants, which spread from a small number of sources. The peak emergence of BA.1.1 and BA.1.1.18 pure reverse mutants occurred a few weeks before the peak of all collected samples, whereas the peak of pure reverse mutants in major BA.1 variants and BA.2 coincides with the overall sampling peak. Although the peaks of BA.1.x collections are not all synchronous, the peaks of pure reverse mutants in the BA.1 lineage completely overlap, with the number of such mutants declining abruptly after the peak. These regional and temporal anomalies in the Omicron BA.1 lineage, especially in the BA.1.1 lineage, are virtually impossible to explain by current theories of natural mutation and spread by human-to-human infection.