San Miguel County on Wednesday ordered its residents to shelter in place as it partners with a private company to test all of its residents for the coronavirus using a blood draw instead of the widespread method of administering oral and nasal swabs.

The shelter-in-place order, the first in Colorado, is effective through at least April 3. The county, in southwestern Colorado and home to Telluride, also prohibited all events with more than 10 people, and ordered all business activities in the county to cease “except for minimum basic operations and essential services.”

Visitors were ordered to return home immediately, and nonresident homeowners are being encouraged to return to their primary place of residence.

San Miguel officials said that the county will partner with United Biomedical Inc., a biopharmaceutical company that develops immunotherapeutics and vaccines for chronic and infectious diseases, to detect and contain the coronavirus. The countywide testing will be the first of its kind in the nation, county officials said.

“This will drastically advance our ability to assess the presence of the virus in our county and allow us to focus isolation strategies,” said Grace Franklin, director of public health for the county, in a news release.

Founded in 1983, United Biomedical is a multinational company headquartered in Hauppauge, N.Y., according to its website.

The plan was announced at an “emergency” meeting of the county commissioners. San Miguel had a population of 7,359 in the 2010 census, and the county seat is Telluride. The Telluride Ski Resort is closed.

Officials plan to test the “entire county” free of charge. Testing will be administered by the county health department.

“Individuals who agree to be tested will receive a simple blood draw by a health care provider,” the news release said. “Tests will then be sent to a lab with results projected to be available within two days. The test ideally will be repeated in 14 days so public health officials can gauge if the rate of infection is increasing or decreasing.”

In the past two days, there were multiple cases of children under age 4 in the region with “serious symptoms concerning for COVID-19.” Several critically ill residents have been hospitalized.

“We’ve entered a new and concerning phase that requires swift action. We have an opportunity to arrest the spread of COVID-19 and potential loss of life,” Dr. Sharon Grundy, county medical officer, said in the release.