Five covid questions scientists still can’t answer

Still, the virus has kept many of its secrets, from how it mutates so rapidly to why it kills some while leaving others largely unscathed — mysteries that if solved might arm the world’s scientists with new strategies to curb its spread and guard against the next pandemic. Here are some of the most pressing questions they are trying to answer:

Where did the virus come from, and why has it been so successful?

Scientists have found very similar viruses in horseshoe bats living in remote caves in Laos, southern China, and other parts of southeast Asia. So far, though, no one has succeeded in drawing a line between the viruses in bats and the Huanan Seafood Market, which sold and butchered live animals in Wuhan, China, and where many scientists believe the virus first spilled over into people.

That theory is backed by multiple lines of evidence, including the clustering of early covid cases around the market — documentation laid out in two peer-reviewed papers published this summer. But key details remain elusive. We do not know where in the market the leap from animals to humans took place, or which animals were involved. Nor do we know the precise steps in the process.

“What particularly drove that spillover?” asked Vincent Munster, chief of the virus ecology section at Rocky Mountain Laboratories, a research facility in Hamilton, Mont., that is part of the National Institute of Allergy and Infectious Diseases. “We’ve now identified 20 or 30 of these viruses that all look very similar, but they are not the same. What is the true hideout place of the progenitor of SARS-CoV-2?”

Several investigations have not been able to categorically rule out the possibility the virus escaped from a laboratory in China, although many scientists believe that is far less likely than that it jumped from animals as part of a natural process.

Escape from a lab could involve at least two scenarios: one, in which the virus evolved in nature and was being studied by scientists; another in which the virus was created in the lab by researchers examining factors that might cause a coronavirus to become more deadly or more transmissible.

Scientists working at the Wuhan Institute of Virology, a major research center that studies coronaviruses, have denied ever having the virus in their laboratories, but that has never been corroborated by outside investigators since Chinese authorities limited access.

Scientists hone argument that coronavirus came from Wuhan market

Whatever its origins, SARS-CoV-2 has proved far more successful at infecting large numbers of people than other coronaviruses, including the one that surfaced in Asia 20 years ago causing severe acute…