Johns Hopkins senior scholar Dr. Amesh Adalja told CNBC on Tuesday that the new coronavirus will likely cause yearly outbreaks, with most of the cases being mild.

"It's going to become a part of our seasonal respiratory virus family that causes disease," Adalja said on "Squawk Box."

However, he expects the current outbreak to turn into a mild pandemic and spread further in the United States. Currently, there's only 11 confirmed U.S. cases, according to the Centers for Disease Control and Prevention.

China's National Health Commission on Tuesday raised its confirmed coronavirus cases in the country to 20,900. The death toll rose to 425 there — with one fatality in the Philippines and one in Hong Kong. The World Health Organization said there's been more than 150 coronavirus cases in about two dozen countries outside of China.

Many health professionals and analysts believe the number of cases to be much higher, which could bring the mortality rate below it's current 2%.

Dr. Anthony Fauci, director of the NIH's National Institute of Allergy and Infectious Diseases, and former FDA Commissioner Scott Gottlieb told CNBC in recent days that they also believe the coronavirus outbreak will turn into a pandemic.

Health officials could declare a "pandemic" if the virus were to start to affect a larger number of people across the globe. The term epidemic is reserved for a more localized spread.

"It's important that we get a handle on what the severity is and who has the risk factors, so that we can protect those individuals," Adalja said. "Many people are going to get mild illness and it's going to be more like a flu-like illness for many people but for some it may be very severe."

Adalja compared the coronavirus to the 2009 H1N1 swine flu outbreak, which is now seen as a regular flu virus. The swine flu pandemic killed about 285,000 people at the time, but it had a low mortality rate. The 2002-2003 SARS outbreak saw 8,098 cases and 774 deaths. That was a mortality rate of 9.56%.

"There are probably a lot more people who were infected in China who have not been really counted ... because they were either asymptomatic or their symptoms were so light that they didn't come to the attention of health authorities," Fauci told CNBC on Monday.

Countries around the globe have responded to the coronavirus outbreak by putting preventative measures, such as travel restrictions, in place. Companies, including Starbucks and Apple, have temporarily closed some China operations.

The U.S. instituted on Sunday a mandatory 14-day quarantine of Americans who in the last two weeks have visited Hubei province in China, where the city of Wuhan, the center of the outbreak, is located. The Trump administration is also instructing Americans returning to the U.S. to undergo a two-week self quarantine if they have been in other parts of mainland China in the past two weeks.

However, Adalja said he's not sure containment efforts will work, since it's a respiratory virus that's already in more than 20 countries. "That really argues against containment."

Dr. Corey Hebert, assistant professor at both Louisiana State and Tulane universities, told CNBC earlier Tuesday that in order to help prevent the virus, people should wash their hands with hot water and soap, get a flu shot, avoid touching their face and wipe areas around them when travelling.