COVID cases drop 25% in Tri-county, but is another winter surge ahead?

October 01, 2021
Transmission electron micrograph of coronavirus particles. Credit: NIAID
Micrograph of coronavirus particles isolated from a patient. Image courtesy of National Institute of Allergy and Infectious Diseases

The number of new infections in the Tri-county area dropped another 24% in this week’s update from the Medical University of South Carolina’s COVID-19 Epidemiology Intelligence Project. There were 2,561 new cases in Berkeley, Charleston and Dorchester counties combined compared with 3,543 the week before.

“Numbers are coming down, but don't get too excited because it's still pretty high,” said project leader Michael Sweat, Ph.D. “It's not time to put your mask away. We're at a fairly high level. It may stabilize and not go all the way back down.”

He described the decline as “flattening,” meaning case numbers aren’t plunging like they were a few weeks ago. “I think you still have to keep your eye on what's going to happen because it really could go back up again.”

Dr. Michael Sweat 
Dr. Michael Sweat

That’s what happened this summer. In June, the Tri-county area got down to almost no new cases per day. Then Delta showed up, leading to the biggest peak in infections of the pandemic.

But why would there be another surge if more people are getting vaccinated, and many have had COVID? Sweat’s own team estimates 74% of the population in the Tri-county area has some immunity to COVID, either through vaccination or infection.

The answer is multipronged. As we’ve seen with breakthrough infections, vaccine immunity may wane. And a lot of people still aren’t vaccinated. The South Carolina Department of Health and Environmental Control reports that just 52% of the people eligible to get vaccinated have completed that process. Nobody under 12 can get a shot yet. 

It’s also unclear how long immunity from a COVID infection lasts. One study suggests at least a year.

The good news is that the hospitalization rate has gone down when you compare this wave to previous surges. During the first wave of COVID in the summer of 2020, about a quarter of the people diagnosed with an infection ended up in the hospital. During the next wave in early 2021, about 15% were hospitalized. And during the current wave, the rate dropped to about 8%.

“I have a theory. I don't know what else to make of it, but I think immunity is working,” Sweat said. “That could be keeping a lot of people from getting really sick.”

But make no mistake, people are still ending up in the hospital. There were 80 COVID patients in MUSC Health-Charleston in the most recent update. Almost 30 are on ventilators, including five children. Almost 80% of the hospitalized patients were unvaccinated when they arrived at the hospital.

Sweat said vaccination is the way for most people to avoid hospitalization. 

So what’s next? Sweat, a professor in the College of Medicine at MUSC who is also affiliated with the Johns Hopkins Bloomberg School of Public Health and is a former research scientist for the Centers for Disease Control and Prevention, said he’s seeing some early signals. “History seems to be repeating itself.”

He points to current Delta-driven COVID hotspots in Northern Michigan, Wisconsin, Minnesota and Iowa. “If you look at last year, the winter wave started in that exact area. What it’s telling me is that this is an area of concern. It's just starting to look remarkably similar to last year. I'm worried that we're going to have another big wave in the winter.”

If we do, though, it could be under more promising circumstancesMany more people will be vaccinated or have natural immunity from a COVID infection than last year at this time. 

And more treatments may be on the way. “I think the technologies are going to improve. There's a lot of promising therapeutics being worked on, antivirals that can be taken orally. I think breakthroughs are going to happen. I think the vaccine work is going to really start to evolve, with vaccines administered nasally that can give mucosal immunity. There's a lot of things in the works,” Sweat said.

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