Image source: WRAL story Jan. 1 featuring packed crowds happy to ring in the new year in downtown Raleigh.

This past week about 98.8% of people in NC were estimated to pose no threat of passing along COVID-19 to anyone. That is the lowest estimate recorded since this same time last year, during the height of cold and flu (respiratory viruses) season. Also about 11 out of 12 (91.4%) adult North Carolinians are estimated to have either vaccine-induced or natural immunity.

A note about that immunity estimate: In keeping with the shifting definitions of “vaccine” and “vaccination” from the Centers for Disease Control and Prevention (see discussion here), the Associated Press recently filed a story explaining “Why are so many vaccinated people getting COVID-19 lately?” While assuring us that “People might mistakenly think the COVID-19 vaccines will completely block infection, but the shots are mainly designed to prevent severe illness,” the AP tells us:

Even though the shots won’t always keep you from catching the virus, they’ll make it much more likely you stay alive and out of the hospital.

This index’s discussion of vaccine-induced immunity is based on the proportion of people who have received a Covid-19 vaccine. It is unfortunately an inescapable limitation of estimating who has (old definitional) immunity from Covid-19.

With respect to naturally acquired immunity from prior infection, there are as of this date 144 research studies attesting to the strength of natural immunity, even in comparison with vaccine-induced immunity. Even properly discounting for vaccination, a seasonal spike in cases means a growing proportion of people with natural immunity.

Here is the NC Threat-Free Index for the week ending January 3. All of the statistics generated for the NC Threat-Free Index are based on numbers provided by government sources. This link gives a detailed explanation of how each statistic is derived. Also note that, now that it is 2022, the population figure being used is the July 2022 population estimate provided by the N.C. Office of State Budget and Management.

  • As of January 3, there were 1,583,210 North Carolinians presumed to be recovered from Covid-19.
  • Active cases comprised 7.5% of NC’s total case count. A case of Covid-19 isn’t a permanent infection. Only someone with an active case of the virus can conceivably transmit it to you. The total case count given banner headlines comprises active cases, the very large proportion of people who have recovered, and the very small proportion of people who have died with Covid-19.
  • Active cases represented 1.2% of NC’s population. Active cases are lab-confirmed cases of Covid-19 minus recoveries and deaths.
  • Also, about 11 out of every 12 (91.4%) of NC’s total cases were recovered. People who have recovered from Covid-19 are no longer infectious. More importantly, a large and growing body of empirical research (“science and data”) shows that they have acquired persistentlong-lasting, and robust natural immunity to Covid-19 — immunity that is stronger against Covid-19 and its variants than even that enjoyed by those who are fully vaccinated.
  • Only 0.18% of people in NC had died with Covid-19. This statistic must be phrased in that manner (“with,” not “from”) because of the lack of clarity over the actual cause of death and because of the research finding as well as DHHS and the CDC admitting that a significant proportion of COVID-19 hospitalizations and deaths were “not related to Covid-19.”
  • All things considered, about 98.8% of people in NC posed no threat of passing along Covid-19 to anyone. This estimate will fluctuate based on relative growth in lab-confirmed cases vs. recoveries.

Herd immunity, reinfections, and post-vaccination infections

For the week ending January 3:

  • Now about 11 out of 12 (91.4%adult North Carolinians are estimated to have some immunity, whether vaccine-induced immunity or natural immunity, the stronger and more durable immunity, to Covid-19. Adults are the ones most at risk of losing their jobs, access to government services, ability to travel, ability to buy groceries, etc., for not being vaccinated even though the ostensible public interest is in immunity. 
  • The total population of North Carolina is at 86.5% immunity. These estimates are based on DHHS case numbers, CDC estimates of actual infections, DHHS estimates of current vaccinations, and the formula outlined here.
  • As of January 3, there had been 22,481 reinfections for those with prior lab-confirmed cases of Covid-19, and the estimated reinfection rate was 1.4%. For reasons discussed here, the actual reinfection rate is likely much lower than the estimated rate. (Note: With this report going forward, I am counting reinfections against the total case count from two weeks prior in order to match the procedure for counting post-vaccination infections after two weeks of vaccination.)
  • Once again, DHHS has not updated data on post-vaccination infections. Also, once again, the official number of fully vaccinated individuals given by DHHS was somehow lower than the previous update’s. Consider how the count has changed since November 6:
    — 5,567,698 fully vaccinated North Carolinians for Nov. 6
    — 5,343,385 for Nov. 27 (the next update):
    — 5,365,512 for Dec. 4
    — 5,302,535 for Dec. 11 
  • The most recent update from DHHS (through December 30) only goes to December 11, when there had been 118,932 post-vaccination infections and the estimated post-vaccination infection rate was 2.2%. Given how strictly DHHS defines a “post-vaccination infection” — as of now, someone must be at least two weeks past receiving the second of two injections; anyone with only one injection or within two weeks of receiving the second “counts” as an unvaccinated case of Covid — the actual post-vaccination infection rate could be much higher than the estimated rate.
  • Also as of December 11, 24% of Covid-19 cases in North Carolina were to people considered fully vaccinated.
  • As of January 3, only about one in 12 (8.6%) adult North Carolinians were estimated to have neither vaccine-induced nor natural immunity.

DHHS discovers another “new” case from 2020

Sometime in the past week, DHHS reported as a “new” case one that had occurred back on October 14, 2020.