The SARS-CoV-2 'perfect storm': From humble betacoronavirus to global pandemic

Abstract

The novel betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global pandemic unprecedented in modern times. Understanding the key features that have enabled this virus to propagate so widely in the global community is critical to current and future clinical and public health efforts. High proportions of mild disease and peak viral loads at, and likely prior to, symptom onset have hindered efforts to identify and isolate infected persons effectively, facilitating undetected spread of the virus. In countries with limited diagnostic and/or contact tracing capabilities, population-wide transmission escalated beyond a critical threshold, challenging even well-developed healthcare systems. This 'perfect storm' for transmissibility has led to widespread outbreaks and deaths in many regions around the world. Extensive testing and contact tracing, together with Australia's geographic advantage, tightening of international travel restrictions, physical distancing and public health messaging measures, have contributed to limiting the extent of coronavirus disease 2019 (COVID-19) spread in the country, but recent case escalation in Victoria highlights the country's vulnerability to future outbreaks due to low population immunity.