G.O.P. Senator’s Report on Covid Origins Suggests Lab Leak, but Offers Little New Evidence

The top Republican on the Senate health committee said in a report on Thursday that the coronavirus pandemic was most likely caused by a laboratory incident in China. The report offered little new evidence, however, and was disputed by many scientists, including those whose research suggests that the outbreak originated instead at a live animal market.

The report, released by Senator Richard M. Burr, Republican of North Carolina, grew out of a joint inquiry with the committee’s Democratic chairwoman that proponents of the effort hoped would add a measure of bipartisan credibility to a highly charged debate.

But the findings published on Thursday, while interim, bore only Mr. Burr’s signature. And in relying largely on existing public evidence, rather than new or classified information, the report came as something of a letdown even to those who supported its conclusions.

“One can only conclude from the circumstances that they met an impasse,” said Richard Ebright, a molecular biologist at Rutgers University, referring to his disappointment that Republican and Democratic staff members working on the inquiry have not yet released a more complete, bipartisan report.