Two Covid Theories

The origin of the Covid virus remains the pandemic’s biggest mystery. Did the virus jump to human beings from animals being sold at a food market in Wuhan, China? Or did the virus leak from a laboratory in Wuhan?

U.S. officials remain divided. The F.B.I. and the Department of Energy each concluded that a lab leak was the more likely cause. The National Intelligence Council and some other agencies believe that animal-to-human transmission is more likely. The C.I.A. has not taken a position. The question remains important partly because it can inform the strategies to reduce the chances of another horrific pandemic.

A recent Times Opinion essay — by Alina Chan, a biologist — refocused attention on the issue by making the case for the lab-leak theory. In today’s newsletter, I’ll try to lay out the clearest arguments for each side to help you decide which you consider more likely.

1. It’s the norm.

Covid is part of the coronavirus family, so named because the virus contains a protein shaped like a spike. (Corona is the Latin word for crown.) In recent decades, the main way that coronaviruses have infected people is through animal-to-human transmission, which is also known as natural transmission.

The SARS virus, for example, appears to have jumped from civet cats, a relative of the mongoose, to humans in Asia in 2002. MERS seems to have jumped from camels to people in the Middle East around 2012. There is no previous example of a major coronavirus originating with a lab leak.

When you’re trying to choose between a historically common explanation for a phenomenon and an unusual explanation, the common one is usually the better bet.

2. Look around the market.

Two scientific papers have pointed out that a suspiciously large number of early confirmed Covid cases had connections to the Huanan Seafood Wholesale Market in Wuhan. Many of these cases, in late 2019, occurred in people who lived near the market. This map comes from a Times story about the research:

Importantly, the market also sold live animals, including raccoon dogs, that scientists previously found to be susceptible to coronaviruses.

3. Look inside the market.

Shortly after Covid began spreading, Chinese scientists swabbed walls, floors and other surfaces inside the Huanan market for the virus. They found a cluster of positive samples in the market’s southwest corner, where 10 stalls sold live animals.

“Strikingly, five of the samples came from a single stall,” my colleagues Carl Zimmer and Benjamin Mueller wrote. That stall appears to have had a history of selling raccoon dogs.

1. Follow the lab.

If historical logic points to natural transmission, a different concept arguably points to a lab leak: Occam’s razor. It’s a philosophical principle holding that the simplest explanation for a phenomenon is usually the correct one. In this case, a new SARS-like virus started in a city with one of the world’s leading labs for researching SARS-like viruses. Many Chinese cities have markets selling live animals; only one is home to the Wuhan Institute of Virology.

The Wuhan lab maintained “one of the world’s largest repositories of bat samples, which has enabled its coronavirus research,” U.S. intelligence officials have written. Before the pandemic, the lab’s scientists traveled to faraway caves to collect virus samples. And bats, like raccoon dogs, can carry coronaviruses.

One possibility is that a virus that would otherwise have remained in the caves infected a lab employee. Another possibility is that scientists in Wuhan engineered a contagious new virus while researching cures and that the virus accidentally escaped.

Notably, there is no evidence of any infected animals, dead or alive, from the Huanan market. Consider this table, from Chan’s Opinion essay:

2. Leaks happen.

In recent decades, reports suggests that laboratory employees working on a variety of diseases have been accidentally infected in the United States, Britain, China, Germany, Russia, South Korea and elsewhere.

Even before the pandemic, the Wuhan lab seemed to present a safety risk. When one outside expert heard that the lab planned to research coronaviruses without using state-of-the-art precautions, he wrote in 2018 that “U.S. researchers will likely freak out.”

3. China controls the evidence.

It’s worth asking which of the two stories China would rather the world believe. Either would be damaging, but a lab leak seems significantly more so. It would mean that China’s scientific incompetence killed millions of people — which could explain why Chinese officials have worked so hard to restrict outside research and scrutiny about the virus’s origins.

Do you find both explanations plausible? I do.

As I’ve followed this debate over the past few years, I have gone back and forth about which is more likely. Today, I’m close to 50-50. I have heard similar sentiments from some experts.

“No one has proof,” Julian Barnes, who covers intelligence agencies for The Times, told me. “Everyone is using logic.” Julian’s advice to the rest of us: “Be wary, keep an open mind, rule nothing out.”

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