The CDC currently does not advise U.S. residents to wear masks unless they are sick themselves. The coronavirus known as COVID-19 passes through most everyday masks.

However, for those who are already ill — whether it’s with flu or the coronavirus, masks can keep cough and sneeze droplets and other contaminants contained, Gulick said.

“Then you're not spreading or spraying the virus around,” he said.

Nancy Messonnier, director of the CDC’s National Center for Immunization and Respiratory Diseases, on Tuesday urged health providers, schools and others to prepare for large-scale disruptions. It was a marked departure from earlier reassurances that the virus could be contained.

“It’s not a question of if this will happen but when this will happen and how many people in this country will have severe illnesses," Messonnier told reporters. “Disruption to everyday life might be severe."

One complication cropping up are online scams and misinformation at a time of growing public anxiety.

It’s not a question of if this will happen but when this will happen and how many people in this country will have severe illnesses. Disruption to everyday life might be severe."

-- Nancy Messonnier, CDC

Attorney General Dana Nessel and the Michigan Department of Health and Human Services warned residents on Wednesday of websites selling fake products and of fake emails and texts and social media used to steal money and personal information — related to the coronavirus scare.

The “messages” might offer phony information about cases in residents’ neighborhoods or prevention tips, but they ultimately ask for donations, offer unproven treatments, or contain damaging email attachments, according to a Federal Trade Commission alert.

Gulick, of MSU, also urged Michiganders to keep facts in perspective: For example, so far confirmed counts of coronavirus indicate it is less deadly than its older cousin coronaviruses, the Middle East respiratory syndrome coronavirus (MERS) and severe acute respiratory syndrome (SARS).

As it stands, this particular coronavirus appears to be lethal in just over 2.3 percent of confirmed cases. By contrast, MERS had a mortality rate of about 34.4 percent, and SARS about 9.6 percent, according to an article published Monday in the Journal of the American Medical Association.

Still, Gulick noted, information on coronavirus is developing everyday, and it’s not clear how accurate earlier case counts in the outbreak in China might have been.

And he cautioned: With the understanding of coronavirus building each day, advice can change in the coming days: “It’s a moving target.”