Health experts say getting an answer as to the source of COVID-19 is priority for protecting the public.

Some theories include coming from a wild animal, China's wet markets or from a lab like Wuhan's Institute of Virology - where researchers looked at bat virus mutations.

"It's gonna affect how we respond to this. We're going to need to focus on trying to get better controls in this sort of high-risk research going forward," says former FDA Commissioner Dr. Scott Gottlieb.

Doctors say they fear history will repeat itself.

President Joe Biden ordered the intelligence community to redouble its efforts in investigating the origin. Rep. Michael McCaul, on the House Foreign Affairs Committee, has alleged the virus was leaked from a lab.

"This is the worst cover-up in human history we've seen resulting in 3.5 million deaths," he says.

There is still no evidence, though - which is why there are calls for an outbreak investigation in China. The Chinese government is refusing full access to the lab and its records.