Dr. Ryan Westergaard, a medical officer for the state health department, told health providers in a webinar Friday that the number of “true cases” of COVID-19 is likely much higher than what is being diagnosed and reported. Several cases around the state are in critical condition, he said.

Reports from China suggest transmission in health care settings was “really a main driver of the epidemic,” Westergaard said. That is proving true in the U.S. with health care workers exposed in the community, he said.

Hospitals should actively monitor symptoms of workers, including taking their temperatures before every shift, he said. If workers develop symptoms, they should be sent home.

“The risk of people coming to work with even simple (upper respiratory) symptoms can have really devastating consequences,” he said.

Reports from China also suggest most cases of COVID-19 are transmitted by people who don’t have symptoms, Westergaard said.

“This really makes it difficult to stop the spread and really is the justification for the extreme social distancing measures that are being recommended,” he said. “Just isolating the known symptomatic cases after diagnosing them is not going to result in decreasing the overall level of exposure to the virus in the communities.”