Transmissibility of the variant of concern for SARS-CoV-2 in six regions

Differences in transmissibility of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) in different districts are hard to assess. To address this, our study focused on calculating the Real-time reproduction number (R ) for these variants in different regions.

According to the criteria defined by the World Health Organization (WHO), the global landscape was categorized into six distinct regions. In each region, the predominant SARS-CoV-2 variant was first identified based on the proportion of variant sequencing analysis results. Then, using serial interval (SI) parameters, we calculated R for the relevant Variant of Concern (VOC) in each region. This approach enabled us to compare the R values of the same variant across different regions and analyze the transmissibility of each region's variant in relation to the overall situation in that region.

The progression of VOC for SARS-CoV-2 shows regional variations. However, a common sequence of evolution is observed: Wild-type → Alpha → Beta → Delta → Omicron. Moreover, an increasing trend is discerned within diverse regions where the shift in R of distinct VOC corresponds with the overarching R route of SARS-CoV-2 in specific regions.

As the COVID-19 pandemic advances, regional epidemiological trends are aligning, likely due to similar virus mutations and shared public health strategies, suggesting opportunities for standardized global responses.