COVID-19 Sudden Outbreak of Mystery Case Transmissions in Victoria, Australia, May-June 2021: Strong Evidence of Tropospheric Transport of Human Passaged Infective Virions from the Indian Epidemic

Abstract

A sudden yet very small outbreak of COVID-19 mystery community transmissions occurred in a defined arc across the inner Western and outer Northern suburbs of Melbourne in May-June 2021. An infection zone that could be 1000 km2 in size. These sudden outbreaks of genuine mystery cases could not be traced to any direct infected contacts nor could they be directly genomically linked to any known infection clusters (e.g. among infected international travellers in hotel quarantine). In response the Government of Victoria on the recommendation of the Chief Medical Officer and the Victorian Department of Health locked down the entire State of Victoria in an extreme Stage 4 emergency. As a consequence, large numbers of PCR COVID-19 tests on oro-nasal swabs were conducted (> 30, 000 per day at peak) and all positives quarantined at home, a directive enforced by police and in some cases the Australian Army. Citizens were neither allowed to leave Melbourne nor from Victoria to any other State of Australia. Contact tracing was conducted on a very large scale by teams of experienced tracers. Several sudden mystery outbreaks continued to occur despite the lock-down on people movements. This included restriction of numbers of visitors at homes, crowd-size limitations, curtailment of sporting events, school closures, mandatory mask wearing, and personal tracking of all individuals in shops and supermarkets (via a personal "QR” digital tracking system linked to mobile phones or via written personal contact statements at store or shop entry). Many of the COVID-19 variants of concern (PANGO classification) were clearly mature human-passaged virions, many of which have been identified in the current and very large 2nd Wave Indian epidemic. We show here there is plausible strong evidence that a heterogeneous set of these "Indian” variants may have been transported by prevailing tropospheric global wind systems via the Indian Ocean and Southern Ocean (Roaring Forties West to East on the 40o S Latitude line) to Victoria, Australia. There is much precedent for such global wind transportations in the history of past Influenza virus pandemics in the last 100 years and the present observations relating to COVID-19 events in Australia are discussed in that context. © 2022 by World Scientific Publishing Co. Pte. Ltd.