OKLAHOMA CITY (AP) — Oklahoma's reported coronavirus cases rose by 377 on Monday, and the state added another death due to the illness caused by the virus, the Oklahoma State Department of Health said.

Oklahoma has confirmed 38,602 cases of COVID-19 and 551 deaths since the pandemic began. The death reported Monday was a man in Pottawatomie County who was 65 years old or older, the agency said.

The true number of coronavirus cases in Oklahoma is likely higher because many people have not been tested, and studies suggest people can be infected and not feel sick.

For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia and death. The vast majority of people recover.

On Sunday, Norman Public Schools became the latest school district in Oklahoma to opt for an online-only start because of the virus. The district pushed back its start date by a week to Aug. 24 and said classes would be held virtually to begin.

Oklahoma City is also starting its school year online because of the pandemic.