Fox News medical correspondent Dr. Marc Siegel reacted Thursday to the latest developments in the coronavirus outbreak, including reports that the virus has mutated at least once.

"We're seeing at least two different strains of this coronavirus. That in and of itself isn't a problem. But will it change more?" Siegel said on "Tucker Carlson Tonight." "Will it change so much that the vaccine we make doesn't fit it? I think the answer to that is no. I think we can get a vaccine to fit all of these strains as long as we track them."

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A preliminary study by scientists at Peking University’s School of Life Sciences and the Institut Pasteur of Shanghai in China found that one strain — type “L” — of the virus was more aggressive and accounted for about 70 percent of the strains analyzed. The second — type “S” — was less aggressive and accounted for about 30 percent of analyzed strains.

"We need to figure out which strain is the one that's really emerging here now in the United States and in Europe," Siegel told Carlson. "Which one, the more severe strain or the less severe strain? That will tell us how many mild cases we have."

"Do you think we're ready for a major outbreak and are we getting one?" Carlson asked Siegel.

"That word is called 'surge capacity.' Can we surge?" Siegel said. "And I'd say we're not ready if we see a lot of cases."

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But Siegel says everything depends on the severity of the outbreak and how much it spreads.

"That's giving our viewers the idea of why we're trying so hard to contain this. The more we contain it, the less we're going to put our hospitals at risk," Siegel said. "But I want to add something positive. Our hospitals are gearing up under the leadership of this task force."

Fox News' Madeline Farber contributed to this report.