Tests by the U.S. Centers for Disease Control and Prevention have confirmed that two Minnesotans who became sick after recent travels to Wuhan, China, were not infected by the novel coronavirus that has emerged there and spread to more than a dozen countries.

The two Minnesotans were among 32 people in the U.S. whose tests for the virus turned up negative, the federal agency reported Monday. The CDC has so far identified five positive cases of the coronavirus in people from Arizona, California, Illinois and Washington state, and is investigating another 110 suspected cases from 26 states.

None of the current cases under investigation by the CDC are from Minnesota, said Doug Schultz, spokesman for the Minnesota Department of Health. The health department had asked the two people with suspicious infections to isolate themselves at home to prevent the possibility that they could spread the virus to others, but Schultz said those restrictions are now lifted.

The negative tests were not that surprising given that this is the peak of the flu season. The CDC has asked states to be liberal in sending lab samples from people who have fevers and respiratory symptoms after recent travels to Wuhan in an attempt to catch positive cases of novel coronavirus infections before they spread.

"We're going to be catching a lot of influenza," Schultz said.

The CDC came up last week with a test for the novel coronavirus, known formally as 2019-nCoV, and is now distributing it to state public health agencies. Schultz said Minnesota expects to have the capability to test for the virus on its own in a couple of weeks.

The continued spread of the coronavirus throughout China and Asia has prompted the CDC to issue travel warnings, discouraging Americans from nonessential travel to Wuhan, and asking them to talk to their doctors before traveling to other parts of China. However, the CDC is imminently considering more restrictive travel recommendations, said Dr. Nancy Messonnier, director for the CDC's National Center for Immunization and Respiratory Diseases.

Federal health officials said the incubation period of the infection is anywhere from two to 14 days, and that so far there is no evidence that people are infectious until they have respiratory symptoms or fevers. Screening of travelers returning from China will continue at five U.S. airports, Messonnier said, in part to check for existing illnesses but also to teach returning travelers what to do if they suffer symptoms later on.

Known coronaviruses cause anywhere from a quarter to a third of common colds in the U.S., but health officials are concerned because this virus is new and has shown the ability to spread through human contact with infected animals but also with other infected people. The coronavirus has been confirmed in more than 2,700 people and 80 deaths in China.