Inherent random fluctuations in COVID-19 outbreaks may explain rapid growth of new mutated virus variants

Bodin, K.; Rocklov, J.

A new virus variant of SARS-COV-2 has had a profound impact on society while governments have taken action to limit its impacts by enforcing lockdowns and limiting spread from the UK to other countries. Variants with mutations in the virus genome are likely to occur, but do not always associate to significant changes in the biology of the virus, or the disease. For the variant VOC 202012/01 (also referred to as B.1.1.7), however, preliminary reports indicate it may be more transmissible. Here we use a simulation model calibrated to the inherent random fluctuating transmission pattern of COVID-19 to investigate what the probability may be for detecting more transmissible virus variants post facto. We find that post facto identification of successful virus variants of SARS-COV-2 are likely to exhibit growth rates that are substantially larger than the average growth rate. This finding has implications for interpreting growth rate and transmissibility of new virus variants.