U.S. health authorities Monday urged Americans most at risk of developing a serious illness from the new coronavirus – the elderly and those with underlying conditions – to stock up on food and medicine and prepare to remain at home.

"Make sure you have supplies on hand like routine medications for blood pressure and diabetes, and over the counter medicines and medical supplies to treat fever and other symptoms," said Nancy Messonnier, a senior official with the Centers for Disease Control and Prevention (CDC). "Have enough household items and groceries so that you will be prepared to stay home for a period of time," she added. Messonnier said that based on a study of 70,000 Chinese patients, about 15 to 20 percent developed a serious illness – most of whom were older adults.

"Starting at age 60, there is an increasing risk of disease, and the risk increases with age," she said, adding: "The highest risk of serious illness and death is among people older than 80-years-old." Messonnier stated that underlying conditions like diabetes, heart disease and lung disease compounded this risk even further.

People in these high-risk categories should avoid close contact with people who are sick, clean their hands often, avoid touching surfaces in public places, and avoid crowds in poorly ventilated spaces.

Over the weekend, the federal government issued fresh recommendations that travelers – particularly those with health conditions – defer all cruise ship travel worldwide. They also recommended that at-risk groups avoid all non-essential travel and long plane trips.

Messonnier advised younger and healthier people to prepare plans to look after elderly relatives. "We recommend you familiarize yourself with your loved one's medication and help them get extra to have on hand," she said. "Help them also get food, medical supplies and other necessities, so they can minimize trips to the store, and create a plan for if they do get sick, and if you get sick. You may need to identify a backup who can take care of them if you can't."

She added that the recommendations "may not be popular" but she was personally making plans for her own parents, both of whom are over 80 and not in an area that has been affected by sustained transmission of the pathogen. There have been more than 550 cases across the country and 22 deaths, according to a tracker maintained by Johns Hopkins University.