'Think carefully': Quest to trace Covid origin spurs debate on work labs do

'Gain-of-function' research gets bad name as world tries to put a lid on how the pandemic started.

At a Senate hearing on efforts to combat Covid-19 last month, Senator Rand Paul of Kentucky asked Dr. Anthony S. Fauci whether the National Institutes of Health had funded “gain-of-function” research on coronaviruses in China.

“Gain-of-function research, as you know, is juicing up naturally occurring animal viruses to infect humans,” the senator said.

Dr. Fauci, the nation’s top infectious disease expert, flatly rejected the claim: “Senator Paul, with all due respect, you are entirely and completely incorrect, that the N.I.H. has not ever and does not now fund gain-of-function research in the Wuhan Institute.”

This exchange, and the bit of