How much should vaccinated South Carolinians worry about ‘breakthrough’ COVID cases?
The surge in COVID-19 cases in South Carolina and across the country is being driven by cases among people who have not taken the vaccine. But a number of so-called “breakthrough” cases have also sprung up among those who have gotten the vaccine.
The unvaccinated are still much more likely to experience serious symptoms requiring hospitalization, and they make up the large majority of those cases taking up the state’s ICU beds.
But up to 14% of those hospitalized at Lexington Medical Center’s COVID wing had previously been vaccinated, and 21% of COVID-19 deaths recorded by the S.C. Department of Health and Environmental Control in July had received the recommended jabs.
Dr. Jane Kelly, assistant state epidemiologist at DHEC, emphasized that the overall rate of breakthrough cases among the vaccinated population is small, so that those who end up in the hospital are a fraction of the millions who who received their shot and avoided the virus. The more people who get vaccinated, the larger the numbers of breakthrough cases we’ll see, she said.
“Before the vaccine was available, 0% of hospital cases were vaccinated, and if we had 100% vaccination, then cases would be fewer, but 100% of hospital cases would be vaccinated,” Kelly said.
She also emphasized that even breakthrough cases among the vaccinated are much less likely to cause serious complications, hospitalizations or deaths, than going unvaccinated.
Most breakthrough cases in S.C. hospitals have been exacerbated by “comorbidities,” the pre-existing conditions that can make a COVID case worse. The state Department of Health and Environmental Control reports that as of Aug. 15, nearly 28% of coronavirus patients reported having a cardiovascular disease; 25% had diabetes; 18% had asthma and 26% said they were current or former smokers. The data did not specific how many were breakthrough cases.
Those conditions can have an outsized impact on fatal COVID-19 cases. While cardiovascular patients accounted for less than a third of all coronavirus cases, they made up 60% of deaths from the virus. Forty-five percent of those who succumb to the disease are diabetics, nearly double their overall share of COVID-19 patients.
Patients with breathing issues caused by COPD, bronchitis or emphysema made up 8% of all patients but 23% of fatalities. Those with a neurological condition made up 6% of patients and 22% of deaths. A history of kidney disease shows up in 20% of COVID deaths, or about five times its percentage among all patients; congestive heart failure shows up in almost 15% of deaths, and cerebral accidents or strokes in 14% — both about seven times the incidence in all COVID-19 patients.
In many of these categories, South Carolina patients report higher rates than the national average, as well as presenting with less well-managed cases of chronic disease.
“In South Carolina, we have poor diabetes and high-blood pressure control,” Kelly said. “So we are set up for having more severe disease.”
Of 114 fully vaccinated people admitted to hospitals in South Carolina in July, 104 had a pre-existing co-morbid condition, Kelly said. Of those fully vaccinated who died, 20 of 21 had comorbidities.
A bigger factor in breakthrough cases can be age. CDC data show that 74 percent of breakthrough cases are among adults 65 or older.
“It’s different when it hits them, because older adults have less of an immune response than others,” Kelly said. “Among those (breakthrough cases) hospitalized, the average age was 72, and among those who died, the average age was 80 years.”
In total, South Carolina’s breakthrough tracker lists 329 confirmed breakthrough cases among the fully vaccinated that resulted in hospitalization, and 77 breakthrough deaths. That amounts to 0.0166% of vaccinated people ending up in the hospital, and 0.0039% who have died.
Around 17% of breakthrough cases in hospitals recorded by the CDC involved cases with no reported symptoms. Those people may have gone to the hospital for something else and tested positive upon their arrival. But DHEC doesn’t include those cases in its data, Kelly said, instead focusing on vaccinated cases who are admitted with COVID-related symptoms.
There are also rising concerns that the COVID-19 vaccines decline in effectiveness over time, even if a shot still gives you a better chance to avoid being hospitalized or suffering serious symptoms, according to a recent study by the U.S. Centers for Disease Control and Prevention. The CDC now recommends booster shots for some Americans, and the Biden administration is recommending booster shots for all members of the general public eight months after their initial inoculation, pending approval from health experts.
But Kelly said it’s not uncommon for vaccine effectiveness to wane over time or to require additional doses to keep patients’ immune responses up.
“It’s normal for antibodies to decrease after vaccination,” she said. “But B cells and T cells are the memory cells. They exist for years in the background, and can re-stimulate antibody production. So I’m not concerned about antibodies decreasing.”
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