Emergence and Growth of Covid-19 Variants
The Covid-19 pandemic has overtaken the world and tested international public health efforts. There has been growing concern with the emergence of variants of the disease and their related implications in controlling the pandemic. We sought to understand the type of growth exhibited by the virus at the times before and after variant of concern emergence. To visualize these growth dynamics, we plotted the growth of the virus in terms of death on a death rate-density graph in the countries of variant origin. These results showed a positive extrinsic growth rate after each variant emerged, suggesting the virus was growing faster than exponentially. The same approach in visualizing virus growth in the United States demonstrated that only the Delta and Omicron variants resulted in faster than exponential growth at time of emergence; the others had little effect on growth dynamics. The faster than exponential growth, termed orthologistic, is unprecedented in mainstream epidemiology and calls for further studies on the contributing evolutionary factors.