27. Why there are good reasons to believe COVID came from other animals and one of the unexpected learnings from the pandemic.

SARS-CoV-2, the virus causing COVID-19 disease, the main villain of the pandemic that took lives of millions around the world. Since the world heard the story of a mysterious disease spreading from a live animals market, there has been plenty of speculations around the origin of the virus. The fact that Wuhan, the city where the first notable outbreak started, has a virus research institute, focusing on coronaviruses specifically, fuelled conspiracy theories from the start. It is also, unfortunately, human nature to try and place blame on somebody, even if it means taking our attention away from working against the actual killer attacking our bodies. Notable politicians, and even some scientists spoke in support of the lab-leak theory. Others went even further, suggesting it was engineered as a bioweapon. WHO investigation team’s report brought even more doubt into the mix, which caused all kinds of theories to gain popularity. Science has recently published a perspective explaining in detail why so many scientists believe SARS-CoV-2 is of natural origin, and made the hop to humans through animal interaction.

The animal origin of SARS-CoV-2 — easy read. Lytras et al. provide us a great overview of attempts to determine the origin of SARS-CoV, the pandemic virus’ relative that caused sporadic epidemics since the early 2000s, and explain how and why this matters for understanding the history of our current attacker. The article touches on multiple important points: genetic proximity of other known coronaviruses to SARS-CoV-2 and geographic locations of sites where different strains were detected, as well as possible ways of making the jump to humans and how such inter-species mutations even occur. It also introduces possible future causes of concern, like reverse zoonotic jump back to other animals. Such development would be catastrophic for the further course of the pandemic, as the virus could mutate further and sporadically jump back to humans causing outbreaks. The text is relatively easy to understand for any interested person, yet detailed enough to deliver a thorough explanation. An important read, especially in the age where misinformation is often weaponized into tools of hate.

On a related note, what positive could come from a virus that prematurely ended lives of millions, halted global economies, yet again deepened disparities between the rich and the poor and uncovered ugly cracks in so many societies around the world? Well, hopefully some of the science being conducted to help curb the pandemic will help us prevent next ones, but also possibly approach other endemic diseases we still fight every year.

Airborne transmission of respiratory viruses — easy read. Wang et al. review how our knowledge of SARS-CoV-2 spread has changed our approach to controlling the outbreaks, and how this reshapes our general understanding of respiratory virus spread. Pre-pandemic, the consensus was largely that viruses shed into small droplets with diameter of 5 micrometers (that is 0.005 of a millimeter), which get projected during coughing or sneezing. Such particles would travel 1–2 meters before falling to the ground, hence we wanted to be farther from any sneezing people and we thought that as long as the infected cover their mouth, we should be roughly fine. As history with COVID has shown, this does not appear to be the case. In fact, until masking mandates were introduced, cities around the globe were experiencing outbreak after outbreak, regardless of the social distancing rules (see #17 and #26.) The next logical explanation was that the virus actually travels through aerosols — even smaller particles (though their actual size is rather ill-defined,) that can stay suspended in the air for hours, especially in closed spaces. They can also travel much farther than a few meters — think how you can smell cigarette smoke when it seeps through ventilation, or when you enter a room where somebody smoked 20 minutes ago. Such knowledge completely changes how we approach preventing the spread of any respiratory viruses. And since face masks work (again recommending #17 and #26!), wearing one may be the most compassionate and smart thing you can do to help protect yourself and others from dangerous viruses, whether it is a common cold coronavirus, flu or SARS-CoV-2.