The estimate of 483,156 people infected may seem large, but it means less than 5% of the state’s population has been infected, and as many as 9.8 million people are still susceptible to the virus statewide.
This indicates that North Carolina is a long way from reaching herd immunity, which occurs when 50% to 60% of the population have been infected. The number also indicates not enough people are being tested, the researchers said.
“We are far, far away from herd immunity,” said N.C. State University professor Julie Swann. “When people were talking about, ‘Oh, we’ll have a second wave in the fall,’ my message was, ‘We haven’t even had the first wave. Everybody is still susceptible.’”
Swann, along with UNC professor Paul Delamater and Ph.D. student Rachel Woodul, set out to make coronavirus estimates and forecasts available to the public.
Their estimates also show some 84,000 people are currently infected with COVID-19 in the state and of those, 41,648 people are infectious. The estimates are as of July 1.
“It’s one thing to know how many have had it. It’s a different thing to know who has it today,” Swann said. “The information about who has it today will tell that person and their closest contacts to stay home.”
The group launched a publicly-accessible website with their models and estimates Friday.
“I just feel like this just needs to be out there,” Delamater said.
A long way to go
Delamater and Swann agree that with less than 5% of the population estimated to have been infected, the state is only at the beginning of its battle against coronavirus.
“The cumulative (number) tells you how many people have had it and how many people have it right now,” said Delamater, whose recent research has included vaccinations and herd immunity. “But it also tells you how many people are still susceptible to get it… and the magnitude of people who are still at risk of getting it.”
Swann said it’s important the public understands that the state has also not yet hit its peak number of cases.
“We are still at the beginning of what we are going to experience in North Carolina,” said Swann, who also worked as a science advisor for the H1N1 pandemic response at the Centers for Disease Control and Prevention. “We are in this for a long time. Individual behaviors will determine what happens.”
The state’s two goals, Swann said, should be to not overwhelm hospitals, and to protect the most vulnerable until there is a vaccine.
North Carolina can achieve those goals by continuing to increase testing and tracing, wearing masks and social distancing.
“We need to continue to ramp up testing and tracing,” Swann said. “I still don’t think we are where we need to be. Everybody needs to find a new normal where we don’t breathe each other’s air.”
How testing shifts the numbers
According to the new estimates, only 14% of COVID-19 cases in North Carolina are lab-confirmed. The state Department of Health and Human Services reported on Thursday that 68,142 people had tested positive.
However, testing has increased dramatically over time. And the researchers estimate that 24% of cases are currently being lab-confirmed.
As testing continues to ramp up, the number of cases the state health department reports should become closer to the actual number of infections, Swann said.
“We are not testing enough yet,” Swann said. “And there is a worry that the supplies for tests are going to be short again.”
If people don’t get tested, however, the gap between reported cases and actual number of cases could grow.
“If more young adults are out there getting infected and have mild or asymptomatic cases who don’t bother getting tested ... it could increase over time,” Swann said.
DHHS reported Thursday that 10% of all tests on Tuesday were positive.
Secretary Mandy Cohen has said she wants that number to be at 5%, according to previous News & Observer reporting.
What other estimates show
Estimates of the number of people who have actually been infected vary, but generally are far more than the number of confirmed cases.
In preliminary results from a study with nearly 20,000 participants, Wake Forest Baptist Health reported between 12% and 14% of people who underwent antibody testing have ever been infected with coronavirus.
And the CDC reported the number of people actually infected is probably more than 10 times the number of lab confirmed cases nationwide. That rate varies state-by-state, however.