(Bloomberg) -- The novel coronavirus spreading across the globe is “10 times more lethal than the seasonal flu,” the government’s top infectious disease official told a House hearing, where he warned the U.S. must take serious mitigation efforts now.

“Bottom line: It’s going to get worse,” National Institute of Allergy and Infectious Diseases Director Anthony Fauci told the House Oversight and Reform Committee. “If we don’t do very serious mitigation now, what’s going to happen is we’re going to be weeks behind” in containing the spread.

Fauci said the U.S. must limit the influx of the virus from abroad and take steps to contain it domestically, including by restricting large gatherings.

He said a vaccine is still at least a year away. Responding to questions, Fauci said he couldn’t give a precise estimate of how many people in the U.S. might get infected.

”It is going to be totally dependent on how we respond to it, so I can’t give you a number,” Fauci said. “If we are complacent and don’t do really aggressive containment and mitigation, the number could be way up and be involved in many, many millions. But if we sought to contain, we could mitigate it.”

The U.S. now has more than 1,000 cases of confirmed infection by the virus, known as COVID-19, according to a Johns Hopkins University tally, which also shows 29 deaths in the country.

Fauci’s warnings are a contrast to the message that has been delivered by President Donald Trump, who has compared it in tweets and statements to the seasonal flu.

On March 9, the president tweeted: “So last year 37,000 Americans died from the common Flu. It averages between 27,000 and 70,000 per year. Nothing is shut down, life & the economy go on. At this moment there are 546 confirmed cases of CoronaVirus, with 22 deaths. Think about that!”

--With assistance from Alexander Ruoff.

To contact the reporter on this story: Daniel Flatley in Washington at dflatley1@bloomberg.net

To contact the editor responsible for this story: Joe Sobczyk at jsobczyk@bloomberg.net

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