The coronavirus outbreak is going to get worse, Dr. Anthony Fauci, the nations leading expert on infectious disease, told lawmakers on Wednesday a warning that stands in stark contrast to the messages coming from President Donald Trump and Vice President Mike Pence.

The coronavirus has infected more than 110,000 people worldwide and is continuing to spread. The disease it causes, COVID-19, was officially declared a pandemic on Wednesday by the World Health Organization.

Fauci and other health experts have worked to emphasize the seriousness of the pandemic: While its impossible to predict at this point how many will ultimately be affected in the U.S., he said it could be many millions if the government and Americans dont take steps to contain the outbreak.

If we are complacent and dont do really aggressive containment and mitigation, the number could go way up and be involved in many, many millions, Fauci told the House Oversight Committee. If we contain, we could flatten it.

He and other public health experts have had to work to counter the number of misleading statements and full-blown lies that Trump has told about the coronavirus outbreak, some of which downplay how contagious the virus is and how dangerous the illness can be. Trump, for example, has repeatedly brought up the common flu, suggesting the coronavirus is no more serious.

Thats incorrect, Fauci said.

People always say, Well, the flu does this, the flu does that, he said. The flu has a mortality of 0.1%. This has a mortality of 10 times that.

Trump, meanwhile, has painted a wildly rosy picture of the outbreak and his administrations response to it.

Just stay calm. It will go away, Trump said after a meeting with Republican lawmakers on Tuesday. Its really working out.