RALEIGH, N.C. (WNCN) — As they consider whether to lift more COVID-19 restrictions, state leaders are watching several sets of numbers — among them, the share of the population that is vaccinated.

“I caution everyone to remember, even as good as these vaccines are, no vaccine is perfect,” state Department of Health and Human Services Secretary Dr. Mandy Cohen said.

While that’s true, new research shows the vaccines may be performing even better than expected.

A study published this week by the New England Journal of Medicine showed how rare so-called breakthrough cases — those who test positive for COVID-19 after being fully vaccinated — can be.


Researchers looked at more than 28,000 health-care workers in California who were fully vaccinated during the surge of cases earlier this year.

Only seven of them — 0.02 percent — tested positive for the coronavirus after more than two weeks had passed since they received their second dose of either the Moderna or Pfizer vaccines.

And those who did have a positive test were either asymptomatic or had only mild symptoms.

Dr. David Wohl, an infectious disease specialist at the University of North Carolina School of Medicine, called the results “clearly remarkable.”

The timeline showed a steady decrease in cases as more time elapsed following the first and, later, the second doses. A total of 145 cases were reported within the first seven days of the first dose.

Credit: New England Journal of Medicine.

“The number of infections just went down and down and down and down,” Wohl said.

The authors called the “rarity” of positive test results two weeks after Dose 2 “encouraging” and say they suggest “that the efficacy of these vaccines is maintained outside the trial setting.”

But they urged further caution, saying the data “underscore the critical importance of continued public health mitigation measures … even in environments with a high incidence of vaccination, until herd immunity is reached at large.”

DHHS reports 1 in 5 adults in North Carolina are fully vaccinated, and more than a third are at least partially vaccinated. Estimates for herd immunity typically range from 70 percent to 85 percent of a population being fully vaccinated.

When could the state get there? That has become a more complicated question with the emergence of the mutated versions of the virus — or, variants — that have begun to spread with increasing speed across North Carolina and the country as a whole.

In North Carolina, the Centers for Disease Control and Prevention has reported 160 cases of the United Kingdom variant — there were 77 earlier this week, and just 40 last week.

“If we do find out that people who’ve been infected with the variant we have now can be reinfected with new variants, well, then it changes everything because then those people are not part of the community immunity.

“But the good news is, the vaccines we have now do offer protection against all variants to some extent,” Wohl added. “So if we can really push forward and vaccinate more and more people, we may outpace the spread of the virus, but the variants are here. And they’re spreading. You know, every day, there’s more variants being spread. That’s bad news for us. And it’s bad news for this effort. So this is a race.”

CBS 17’s Joedy McCreary has been tracking COVID-19 figures since March 2020, compiling data from federal, state, and local sources to deliver a clear snapshot of what the coronavirus situation looks like now and what it could look like in the future.