We Still Don't Know the Origin of COVID-19

The lab leak hypothesis received a boost this week, but the question remains unresolved.

By Ryan McGreal

Posted March 03, 2023 in Blog (Last Updated March 03, 2023)

Is it even possible to discuss the origin of the SARS-CoV-2 virus fairly and rationally? What the heck, let's give it a go.

First: we still do not know where the virus originated and how it first came into contact with humans, and anyone who claims differently is lying to you.

Most pandemic viruses are zoonotic in origin, which means they start out in an animal population. This often begins in populations of domesticated animals living in close proximity, which provides 'amplification loops' for a series of mutations that allows the virus to jump species from its original host, perhaps through an intermediary, and on to humans and to be transmissible among humans.

The original SARS outbreak in 2002 was traced to horseshoe bats in southwest China and made the jump to humans through civets, which are a species of mammal that live in the same region. The MERS outbreak in 2012 was traced to zoonotic transmission from dromedary camels in the Middle East.

Because zoonotic transmission is such a common pattern, it serves as the default hypothesis for the origin of the novel coronavirus that caused the COVID-19 pandemic. But researchers have not yet discovered a clear pathway for how exactly that might have happened.

An early conjecture suggested that the coronavirus started out in a population of horseshoe bats, since it is genetically similar to other coronaviruses circulating among them, then jumped to pangolins as an intermediary and then to humans.

Another early conjecture is that the virus mutated and jumped species within a Chinese "wet market" - a market that includes fresh produce, meat and livestock from various farmers - and the Huanan Seafood Wholesale Market in Wuhan was identified early on as a likely culprit after an outbreak that began there. Several species that are known to be intermediate or reservoir carriers of coronaviruses were sold at the market, which was closed permanently in January 2020.

Zoonotic transmission is essentially the "null hypothesis" of COVID origin - the baseline assumption, the thing you would expect if this pandemic is similar in origin to all the other pandemics scientists have studied. Most scientists continue to believe that the most likely origin of COVID-19 was zoonotic transmission, and reviews and meta-analyses of the scientific literature consistently point to this as the most likely conclusion, even though the data are not conclusive.

But there is an alternative hypothesis which has been circulating since early in the pandemic: it is also possible that the SARS-CoV-2 virus was collected by researchers from a bat population, brought to the Wuhan Institute of Virology for storage and analysis, and then transmitted to humans through accidental exposure to someone working at the lab, who unwittingly carried it outside and introduced it to the wider community.

This hypothesis is at least plausible. After all, the location of the virology lab is not far from where the virus first appeared in humans, it is a facility where researchers collect and study coronaviruses, and international agencies - including the US State Department - had issued warnings about safety concerns regarding the facility's storage and handling of viruses.

The lab leak hypothesis spread widely among conspiracy theorists early in the pandemic, linked to more outlandish claims that the virus was genetically engineered and/or released deliberately, and has continued to circulate ever since. Early in the pandemic, some social media companies tried to down-regulate the circulation of conspiracy theories on their platforms and were accused of engaging in censorship and suppression.

It is reasonable to assume that the association of the lab leak hypothesis with reckless and bad-faith actors rendered it even less appealing to scientists trying to do legitimate research, and the small group of scientists who have been interested in this hypothesis argue that the mainstream science community was too quick to dismiss it.

An investigation by the World Health Organization in early 2021 concluded that the lab leak hypothesis was very unlikely but could not rule it out as a possibility. Further, the Chinese government has been tight-lipped and uncooperative with international researchers, making the job of solving this mystery more challenging - and fueling the suspicions of conspiracy theorists pushing more nefarious claims.

The lab leak hypothesis received a boost this week from the US Department of Energy, which now believes this is the most likely origin - albeit with only a low level of confidence in that conclusion. And they do so citing classified intelligence, so independent parties cannot review how it came to this conclusion.

The DOE joins the FBI in favouring the lab leak hypothesis, but the other US agencies which have been studying this matter are divided in their conclusions.

The National Institute of Allergy and Infectious Diseases (NAIAD) and the Centers for Disease Control (CDC) still believe zoonotic transmission is the most likely origin, while the Central Intelligence Agency (CIA) and National Intelligence Council (NIC) have not drawn a consensus on which hypothesis is more likely.

One thing the agencies do agree on, however, is that they have ruled out the various conspiracy theories suggesting that the virus was either engineered or released deliberately. So if you see a conspiracy theorist pointing to news reports about the DOE analysis and yelling "I TOLD YOU SO", you are right to be highly suspicious of that person's intentions.

It is not unreasonable to suspect that an accidental lab leak may be the pathway that introduced SARS-CoV-2 to humans, but it is objectively wrong to claim either that the debate is over or that scientists and agencies favouring the zoonotic hypothesis are engaged in some kind of cover-up or suppression.

The bottom line is that we still don't know the origin of COVID-19. And if you are wondering why it is taking so long to confirm the origin, please understand that it's normal for this painstaking work to take a long time. It took 14 years of careful research to confirm the origin of the original SARS virus from 2002.

So it might still be a while before this matter is finally settled, one way or another.