The big surge of coronavirus cases that washed over Orange County and throughout Southern California over the summer has eased significantly, and local officials are now watching closely to see if the lower case levels can be maintained as schools reopen.

“We’ve been making good progress in Orange County, and I thank our hospitals, first responders, health care workers, and our residents,” said Michelle Steel, the chair of the Orange County Board of Supervisors, at a news conference Thursday afternoon. “We are heading in the right direction and our numbers are low, and I hope to see Orange County continue to make progress.”

But Steel warned that the public needs to remain vigilant and continue to take precautions, such as wearing masks and social distancing, as schools reopen. Five Orange County school districts, or 139 schools, serving about 76,000 students began classroom instruction Thursday.

Five more districts are expected to open for in-person instruction by the end of the month.

“We have to keep in mind that we are still in this fight against COVID-19, and we will get out of it much faster if we all work together to keep fighting this virus by protecting ourselves and those around us,” Steel said.

July was a brutal month for the coronavirus pandemic when Orange County and Los Angeles were hit harder than other California counties.

By raw numbers, Orange County had the second-highest number of coronavirus infections in the state — behind only Los Angeles County — on July 20. 

But those numbers have fallen dramatically in September.

Over the past week, the county has averaged 183 new cases and 9.3 new deaths per day. 

On Thursday, the O.C. Health Care Agency reported 84 new cases of the virus and six deaths Thursday, bringing the total number of positive cases to 52,622, with 1,182 deaths linked to the virus.

Health officials also gave an overview of the COVID-19 response plan for opening schools to in-person instruction at Thursday’s news conference.

Dr. Matthew Zahn, medical director of the Communicable Disease Control Division for the Orange County Health Care Agency, said case investigators are responding within 24 hours of a reported COVID positive case in the community.

“That means any person, child or adult who has a case, we are reaching out to and identifying any contacts they have,” Zahn said. “If they have a school contact, then we will identify whether there is a risk or a contact at that school. And if there is we will reach out to the school immediately.”

In the event there are multiple cases or outbreaks within the school or community, Zahn said the response is different depending on the situation.

In the event a student or a teacher contracted the novel coronavirus from a household contact and went to school while infectious, Zahn said the county health agency will investigate immediately.

“We certainly know that that is likely to happen over time,” he said. “In those situations it won’t be that there’s an outbreak per se and it won’t be that there’s any transmission that’s happened at the school.”

If two people who were in the same classroom acquired the virus at home and went to school, Zahn explained, that wouldn’t necessarily count as an outbreak at school because “you’re not seeing transmission within the school at the same time” those people acquired the virus.

“What functionally happens is, whenever we have the concern, we will talk to the administrator or nurse associated with the school and talk through the issues to make sure everybody understands who are potential exposures,” Zahn said.