Scientist sees new phase as COVID cases rise again: From ‘pandemic’ to ‘endemic’

July 22, 2021
Transmission electron micrograph of SARS-CoV-2 virus particles isolated from a patient.
Transmission electron micrograph of SARS-CoV-2 virus particles, isolated from a patient. Courtesy of National Institute of Allergy and Infectious Diseases

The average number of COVID cases per day in the Tri-county area over the past week was relatively low: 12 for every 100,000 people. But it’s the growth rate that has public health expert Michael Sweat, Ph.D., worried. “We’re seeing 60% growth,” he said.

Are we in for a spike? Sweat hopes not. But he’s wary, based on what’s happening in the U.K., Missouri, Arkansas, Louisiana and parts of Texas and Florida, where COVID infections have soared in recent weeks.

“My experience in the past is you sometimes get these inflection points, where the case numbers go up and up, and then suddenly, they just shoot up. That kind of makes sense with social networking, how you get enough critical mass, and it's a logarithmic kind of growth,” Sweat said.

We have a couple of things going for us that could reduce that risk. “There are a lot of people who are vaccinated, and we have a lot of natural immunity going on in people who have already had COVID. But there are enough people who aren't vaccinated – it’s a smaller population of vulnerable people – to get infected by a massively more transmissible virus.”

Dr. Michael Sweat 
Dr. Michael Sweat

The delta variant, now the dominant COVID strain in the U.S., spreads much more easily than earlier versions of the coronavirus that started the pandemic. It also makes people sick more quickly. 

study just published in the New England Journal of Medicine highlights the importance of getting fully vaccinated to protect against delta. People who want to get a shot can find a location through the South Carolina Department of Health and Environmental Control. 

And Sweat said it’s time for us to start seeing COVID in a different way. The pandemic seems to be shifting to an endemic situation, meaning the virus could remain a constant presence. “I think it's not going away. You want to think it's over. We're all tired of it,” Sweat said.

“But it's all over the world. We know this virus can mutate and become more transmissible. We have to figure out how to live with it, I think.”

That includes figuring out the best ways to protect people in the long term. “COVID’s mortality has already gone way down because of vaccines and natural immunity. We need to learn more about things like how long a vaccine lasts and how long natural immunity lasts.”

Sweat’s COVID tracking team at the Medical University of South Carolina will continue to monitor the virus’ spread and give big-picture updates once a week, usually on Thursday. It updates the seven-day average number of cases per day on a daily basis. 

It also gives immunity estimates. This week, his team estimates immunity in the Charleston area at about 64% when you factor in people who have had COVID and people who have been vaccinated.

“I have some hope that when if we see a bigger surge here, it will encourage some of the reticent people go ahead and get vaccinated,” Sweat said.

“We may stumble our way closer to kind of herd immunity. That won’t stop it, but it will make it more like the flu as we go into the years ahead, that's really my prediction. I think you're going to have to get a booster shot. Every year, there are going to be outbreaks - certainly, vulnerable people are going to get it, and we'll learn to live with it. Like we did the flu. They weren't seasonal flu outbreaks before the 1918 flu pandemic. Over the years, we’ve have learned to live with it.”