At least 35 people in the United States are infected with the novel coronavirus, and US officials are working with state and local health departments to prepare for a possible pandemic, according to the Centers for Disease Control and Prevention, or CDC.

The 35 include 14 US cases and 21 repatriated individuals－18 from the Diamond Princess cruise ship docked in Japan and three evacuated from Wuhan, the epicenter of the disease in China, the CDC said.

Another 10 passengers from the Diamond Princess tested positive in Japan but aren't counted among the 18 because the CDC said it has yet to confirm their tests.

The CDC said on Friday that it will change the way it reports on cases in America. It will separate those who have been repatriated from other countries to the US and those whose infections occurred on home soil.

The US repatriated 329 Americans this week from the Diamond Princess. Several American passengers onboard are still being treated in Japan, the CDC said. The number of cases in the US is expected to rise based on infections developed on that ship.

Despite the increase in numbers, Nancy Messonnier, the director of the CDC's National Center for Immunization and Respiratory Diseases, said at a news briefing on Friday that it is not detecting the spread of the virus in US communities. One person in Humboldt County, California, tested positive, authorities there reported Thursday. That person had traveled to China, the CDC said.

Messonnier also suggested that the US may also close schools and businesses as virus-stricken areas in China did to contain the virus. "The day may come where we may need to implement such measures in this country," she said.

Messonnier said the CDC is expanding its surveillance for the disease, however, and preparing for the possibility that COVID-19 could spread more widely in the US.

"This new virus represents a tremendous public health threat," she said. "Our goal continues to be slowing the introduction of the virus into the US."

Messonnier said the CDC is working with supply chain partners, hospitals, pharmacies and manufacturers to understand what medical supplies are needed. "This will help CDC understand when we may need to take more aggressive measures to ensure that healthcare workers on the front lines have access to the supplies that they need," she said.

Reuters contributed to this article.