RALEIGH, N.C. (WNCN) — Thousands of new cases of COVID-19 in North Carolina keep streaming in every week during this latest surge.

But what we don’t know is how many of those are breakthroughs.

That’s because the weekly count from the state Department of Health and Human Services has quietly disappeared — after months of including it in the weekly Respiratory Virus Surveillance report.

It could be a big problem — when it comes to data, not often is less actually more — but doctors say the agency’s rationale behind the decision to remove those updates makes sense.

“At this point in time, several years into the pandemic, and over a year into starting the vaccinations, it’s no longer as meaningful to us,” said Dr. Erica Pettigrew, a family medicine physician and assistant professor at the University of North Carolina School of Medicine.

Our state isn’t the only one to stop publishing that count: New Mexico, for example, also removed its post-vaccination case data from its public reports.

The last updated count of breakthrough COVID-19 cases from NCDHHS was posted April 21. It was removed from the weekly respiratory virus surveillance report a week later and has not returned. (Photo credit: NCDHHS)

The last update from NCDHHS came in the report published April 21 and covered the period from New Year’s Day 2021 through April 9 this year.

It counted a total of more than 540,000 post-vaccination cases, with nearly 434,000 of them in people who had been vaccinated and another 106,000 in those who received booster shots.

In a statement, NCDHHS called the raw total of breakthroughs “difficult to interpret” but says it continues to track them even if that total is no longer being published weekly.

“Recent trends in reported case rates by vaccination and booster status have become difficult to interpret given differences in time since vaccination and the high rate of recent past infections, particularly in the unvaccinated population,” NCDHHS said. “The raw number of post-vaccination cases is also difficult to interpret for similar reasons.”

It’s a significant complicating factor that people have different levels of protection based on the timing of the shot or shots they’ve received. Someone who only received the primary vaccine series last spring has much less protection than another person who has been double boosted.

“There are too many of those variables to package into one nice, clean number,” Pettigrew said.

And because so many people test at home — and those numbers are seldom reported to public health officials, and rarely factor into those case counts — the overall number is surely a massive undercount.

Yet NCDHHS still considers the case count one of the seven key measures it tracks

So why not break them down by vaccine status?

Dr. Thomas Holland, an infectious disease specialist at the Duke University School of Medicine, says it’s not that simple.

“I think it’s still informative to just look at the total number of cases, but it’s become harder to tie them together with sort of a rate of vaccinated versus unvaccinated people,” he said.

Breakthroughs were such a big deal early on in the pandemic because there are two types of immunity: Sterilizing, which means a vaccinated person would never catch the disease, and functional, which means a vaccinated person can catch the disease but is largely protected from the most serious cases of it. Public health experts weren’t sure which type the vaccines would produce.

“So it was really important to track it at the beginning of vaccinating so many people because it was a question that we didn’t yet have the answer to,” Pettigrew said.

“If somebody has a breakthrough infection, we anticipate it, we know that it happens, we also feel very confident that the hospitalization and death rates are much lower for those who are vaccinated,” she added.

“So we still need to focus on getting people vaccinated and getting people their boosters. But as a metric, it’s less meaningful to us to track the breakthrough infections over time.”

Dr. Pia MacDonald, an epidemiologist at RTI International, agrees with the agency’s rationale but says breakthroughs will still be important track — but the best way to do it is in the clinical setting, she said.

And they will be even more important to monitor as more variants evolve.

“With each new variant, it’s critical we understand who’s getting infected with those, what is changing about the effectiveness of the vaccine, what’s changing about how much a previous infection protects us,” she said. “So in terms of understanding the epidemiology, it does remain an important indicator for us. But where we can see it, the clinical setting is an efficient way to do that.”

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.