Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, did not discount the theory that SARS-CoV-2 originated in a laboratory, but said historically, coronaviruses “generally come from an animal origin.”

According to CNBC, Walensky expressed her opinion during a Senate testimony Wednesday adding that she hadn’t seen enough data to support her view on how the pandemic started.

There has been widespread speculation that the virus originated in a laboratory in Wuhan, China. Although the World Health Organization published a global study in March that said it was “extremely unlikely,” the virus came from a lab, the WHO director general, Dr Tedros Adhanom Ghebreyesus, said that he did not “believe the assessment was extensive enough” and urged researchers to go back and gather further data.

“Although the team has concluded that a laboratory leak is the least likely hypothesis, this requires further investigation, potentially with additional missions involving specialist experts, which I am willing to deploy,” he said in his closing remarks about the report.

Other scientists agree. A letter from scientists published in the journal Science, said that “theories of accidental release from a lab and zoonotic spillover remain viable,” and called for a new and truly independent investigation of all possible origins of the COVID-19, including the alleged laboratory accident releasing the virus in Wuhan, The Hill reported.

"Understanding the origins of the pandemic is essential to addressing our vulnerabilities and preventing future crises," the letter read. "Unfortunately, as outlined in previous open letters released on March 4 and April 7, structural, procedural, and analytical shortcomings of the WHO-convened joint study into COVID-19 origins have created unnecessary barriers to this understanding."

The CDC’s website says that the virus probably came from a bat, although the agency admitted that the exact source of the outbreak is unknown, according to CNBC.

When Walensky was questioned about her opinion concerning the source of the pandemic by Sen. John Kennedy, R-La., during Wednesday’s hearing on the CDC’s budget for the next year, she said, “I don’t believe I’ve seen enough data, individual data for me to be able to comment on that.”

Kennedy asked about possible sources and the director replied that most coronaviruses that have infected the general population such as SARS-CoV-1 and MERS came from an animal origin.

According to CNBC, Kennedy asked, “Are there any other possibilities?”

“Certainly, a lab-based original is one possibility,” Walensky replied.