Cases of the new coronavirus are increasing in southeastern Mississippi, and the state health officer said Friday that people need to follow safety precautions.

“Simple social distancing works,” Dr. Thomas Dobbs wrote on Twitter. “Stay away from large groups. Avoid social gatherings. Stay (more than) 6 feet away from others. Wear a mask in public. Wash hands/use sanitizer.”

The Health Department said Friday that Mississippi — with a population of about 3 million — has had at least 16,769 cases and 803 deaths from the coronavirus as of Thursday evening. That was an increase of 209 cases and nine deaths from the numbers reported a day earlier.

The number of coronavirus infections is thought to be far higher because many people have not been tested, and studies suggest people can be infected without feeling sick.

For most people, the coronavirus causes mild or moderate symptoms that clear up within weeks. For others, especially older adults and people with existing health problems, it can cause severe symptoms and be fatal.

The Health Department said Friday at least 1,969 cases of the virus have been confirmed in long-term care facilities such as nursing homes, with at least 410 virus-related deaths in those facilities.

The department said 201,670 coronavirus tests had been conducted in Mississippi as of Thursday; 8,662 of those were blood tests that detect whether a person has antibodies that usually show up after an infection is resolved.