Origin of SARS-CoV-2

Welcome to another piece from the long saga of posts talking about COVID in one way or another - it just really is a topic that keeps on giving. In this volume of my thoughts about COVID, I would like to talk about a topic recently refloated by vigilant scientists and media - the Origin of SARS-CoV-2.

You might have thought that it was firmly established that SARS-CoV-2 originated by a zoonotic spillover from another mammalian species, like we know it was the case with the eight previous coronaviruses known to infect humans within the last 20 years. At least for now, however, the answer is big: we are not sure. The truth is that there is no conclusive evidence supporting any hypothesis about the SARS-Cov-2 origin. We know that the first epicentre of COVID-19 is the Huanan market in Wuhan, China. We know live animals susceptible to coronaviruses and associated with past coronavirus spillovers (e.g., SARS-CoV in Guangdong province, China in 2002 and 2003), like civets and raccoon dogs, were traded here since at least 2017. From the Huanan market, the virus likely spread to other Wuhan live animal markets, and from there, it slowly conquered the world. Sadly, thus far, we have failed to identify any animal reservoir of SARS-CoV-2 or its close ancestor - significant evolutionary gaps exist among SARS-CoV-2 and its closest known viral relative.

Some scientists have also long been pointing to the Wuhan Institute of Virology (WIV; one of the biggest coronavirus laboratories in the world) as a potential source of the virus - most likely due to human negligence or poor bio-security of the institute, where a few individuals would have had been infected by the virus and transmitted around the Huanan market. There is precedent for such leak, albeit never at such a scale, and indeed, a previous inspection of WIV pointed out poor safety standards. It is worth mentioning that WIV had worked with SARS-CoV-2's closest known genetic match (although not necessarily its closest known evolutionary relative) - the RaTG13 coronavirus (isolated from bats in Yunnan, China). Additionally, reports indicate that several WIV researchers presented with COVID-19 and thus flu-like symptoms in the autumn of 2019 before the first recorded cases of the illness. It is unknown whether this is related to the emergence of SARS-CoV-2 or just a case of the common flu. WIV claims zero infection among staff and students of SARS-related viruses and, additionally, reports that no samples from its repository match the SARS-CoV-2. Nevertheless, Chinese institutions are known to be unreliable, and seemingly, Chinese authorities are spending much effort to obscure events that took place early-on during the pandemic and to block any inquiry into the matter. Additionally, there are some genetic clues in SARS-CoV-2 had been accustomed to humans some time before the break out in Wuhan, nevertheless this could have been both in a natural yet-unidentified population pool from which the virus spread to the Huanan market or in a research environment.

Even though the animal origins of many well-known human pathogens (e.g., Ebola, Hepatitis C, or the poliovirus) are also not yet known even after years of investigation, meaning that we are still relatively early into the study of the origins of SARS-CoV-2, it is imperative we allow an independent inquiry into the matter while the evidence is still fresh, as even if SARS-CoV-2 originated in a zoonotic spillover, we must thoroughly examine it to help us fight SARS-CoV-2 and to prevent similar events from happening in the future. At present, without any other supporting evidence, we can only speculate about the history of SARS-CoV-2 before its emergence from Wuhan markets. Hopefully, more light will be soon shed on the origin of the pandemic tormenting our lives for the past 18 months.

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