As coronavirus spreads in the United States and around the world, there are several important questions about the disease that remain unanswered, CBS News medical contributor Dr. David Agus said.

For example, "I don't know its infectivity rate. I don't know exactly how it's transmitted. I don't know how long someone is infectious. I don't know if someone gets an infection — a year later, can they get a reinfection with this virus? Those are all unanswered questions," he said on "CBS This Morning" Thursday.

Agus said doctors and others need to work together to get those questions answered.

"When you have the head of the World Health Organization say I'm not really sure what's going on, to me that's a very scary moment," he said, adding that the scientific community and political leaders need "to get together and start to say, 'Here are the questions we need answered' and to divvy it up and all of us together, come up with answers."

There are nearly 97,000 reported coronavirus cases in 81 countries, and more than 3,300 people have died. In the U.S., there are more than 160 cases and there have been 11 deaths.

More testing needs to be done in the U.S., Agus said. He called the drive-through testing system in South Korea "brilliant" and said a system like that could be beneficial in the U.S.

"The problem is, we don't know the death rate in our country or around the world because we don't know who has the virus. So if you change the numerator — that is the number of people being tested — we can get real data, enact policy and have leadership," he said.

Though a vaccine is at least a year away, Agus said there are drugs meant to treat other viruses that doctors believe will work against coronavirus as well.

"We have drugs that we think they work, and they're being tested now in clinical trials in Nebraska and in Europe. Some of those drugs are already on the market for HIV and influenza. Others are newer drugs meant for those diseases but work against this one," he said.

Agus also said there is a "relatively low risk for anybody having a complication from coronavirus in this country.

"It will happen, but it's a very low rate."