‘Breakthrough’ COVID cases make up a small fraction of NC’s fully vaccinated, experts say

The rise in new cases of COVID-19 in North Carolina and across the country has prompted concerns about “breakthrough” infections in vaccinated people. But recent data from the state’s health department show those infections have occurred in an exceedingly small percentage of the 4.9 million North Carolinians who have been fully vaccinated.

As of Aug. 5, 4,946,603 North Carolinians had completed their full course of COVID vaccination, either through the two-dose Pfizer or Moderna vaccines, or the one-dose Johnson & Johnson vaccine, according to the N.C. Department of Health and Human Services.

The state health department reported just 7,297 potential breakthrough cases between January, when the first people in the state were fully vaccinated, and July 22, the date for which the most recent information is available. Those cases included 383 hospitalizations and 66 deaths, the state DHHS reported. As of the week of July 19, a little more than 4.9 million North Carolinians had been fully vaccinated.

“The increase in breakthrough cases is due to the current surge in cases and also includes potential breakthrough cases from earlier weeks that were not identified in previous linkages,” NC DHHS spokesperson Bailey Pennington told The News & Observer in an email.

Since May 6, nearly 92% of new cases and 94% of deaths in North Carolina have been in people who were not fully vaccinated, Pennington said. It isn’t known what percentage of those cases and deaths occurred in people who were partially vaccinated versus those who were unvaccinated.

Breakthrough cases in North Carolina, the country

Breakthrough cases are defined as new COVID-19 infections in people who are fully vaccinated but may be exposed to the virus that causes the disease, according to the Centers for Disease Control and Prevention, which says “there will be a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from COVID-19.”

In North Carolina, as of July 22, there were roughly 1.5 breakthrough cases for every 1,000 people who were fully vaccinated. The rates of known hospitalizations and deaths among those cases were even lower, at approximately 0.8 hospitalizations per every 10,000 fully vaccinated people and 1.3 deaths per every 100,000 fully vaccinated people.

Nationally, a total of 6,587 people with breakthrough infections were either hospitalized or died as of July 26, according to data submitted to the CDC from 49 states and territories. By that point, more than 163 million Americans had been fully vaccinated, the federal agency says.

Of those 6,587 hospitalized or fatal breakthrough infections, 4,868 cases, or roughly 74%, occurred in people aged 65 or above.

The agency previously monitored all reported breakthrough cases but transitioned to focusing only on hospitalizations and deaths beginning May 1, to “maximize the quality of the data collected on cases of greatest clinical and public health importance.”

Who is getting breakthrough infections in NC?

Dr. Sylvia Becker-Dreps, an associate professor of family medicine and epidemiology at the UNC Gillings School of Global Public Health, said it would be better to compare the number of breakthrough cases against the number of vaccinated North Carolinians who would’ve gotten infected, hospitalized or died had they not been inoculated.

“Remember that on a whole, those who got vaccinated were older, had more chronic conditions, and had a higher risk of exposure (e.g. health care workers) than those who were not vaccinated,” Becker-Dreps wrote to the N&O in an email. “Therefore, to me, I am still astounded by how effective this vaccine is, even against the delta variant.”

The vaccines being used against COVID-19 are similar to all the other vaccines that have been developed and used to fight previous infectious disease outbreaks, Becker-Dreps said, in that a certain percentage of people won’t respond to the vaccines “due to a glitch in the person’s immune system, or due to factors we don’t fully understand and can’t predict.”

“Regardless, even if vaccinated people get infected, they tend to have much milder symptoms, even from the delta variant,” she said.

It’s also important to consider who comprised those who died from contracting the virus after they had been fully vaccinated, said Dr. Cameron Wolfe, an associate professor at the Duke University School of Medicine.

Wolfe said the majority of the patients hospitalized with breakthrough infections that he was aware of had “significant immunosuppression,” meaning that their immune systems were already suppressed from conditions like leukemia or treatments like chemotherapy or a heart transplant.

“In other words, we now know they don’t respond to vaccines as effectively,” he said in an email. “So if you take them out of the equation, the rates of significant illness in the vaccinated is even lower.”

More breakthrough cases coming due to Delta variant

People should expect the number of breakthrough cases to be higher over the next few weeks, Wolfe told the N&O, “because we simply have more covid exposures.”

“That’s exactly why the CDC encouraged us to go back to masks indoors or in crowded areas for the time being, to protect all of us,” he said.

The CDC issued new guidance for mask-wearing last week, recommending that people wear masks in indoor public places in areas that have “substantial” or “high” transmission, even if they’re vaccinated. The federal agency also recommended universal mask-wearing in schools, irrespective of vaccination status.

Still, that doesn’t mean we should be disappointed by the vaccines, Wolfe said, adding that it’s “in fact more of a celebration at the mortality drop.”

“Becoming critically ill from (COVID-19) is now officially a preventable disease,” Wolfe said.

On Aug. 5, North Carolina reported more than 4,331 new cases of COVID-19 — the highest one-day increase since mid-February, The News & Observer reported.