Are Minnesota’s Herd Immunity Goals Already in the Rear View Mirror? 

On March 9^th, the California Medical Association presented survey results of 79,000 residents displaying that 38% carried COVID-19 immunity antibodies. The findings were gathered from blood banks and clinics across the state. The fascinating part of that study was the timing. It was conducted through February 20th when barely 5 percent of Californians were fully vaccinated, and only 11 percent had received their first shot (according to USA Facts). That left an intriguing gap of 27-33 percent of the population that had been infected and still carried protection.

At that same time, Dr. Fauci, Director at the National Institutes of Health and Chief White House medical advisor, was setting a U.S. herd immunity target of “70 to 75 percent” of the population. While Fauci has been quietly moving his target upwards, the World Health Organization continues to promote the 70-75 percent benchmark.  

Back in the land of 10,000 Lakes, the California results immediately draw the question about how much of our population is already carrying COVID-19 immunity --  yet not vaccinated? Recently the State reached 54 percent of the population with one shot but is there another hidden vein of citizens with antibodies that have already propelled us beyond some of the major herd immunity goals?

We sought out the Minnesota Department of Health (MDH) and they delivered surprisingly useful data. Their team ran reports from several blood banks. Media Relations spokesperson Erin McHenry wrote: “For Blood Bank A, the most recent data we have is from the week ending May 10.

•    84.1% of their donors were positive for antibodies against SARS CoV-2. The antibody test used detects both natural infections and antibodies from vaccination.”

MDH cautioned that donors may not reflect the general population because they may be older, healthier and less diverse than the general population. That being said, 84 percent of donors carrying antibodies are stunning. That level far exceeds even the highest global goals for herd immunity.

With the MDH sample limitation in mind, we dug further into an outstanding resource from the CDC. It adds the missing component from the Minnesota data — antibodies from health clinics. The CDC Seroprevalence Study regularly runs 1300 State blood samples and can eliminate patients that have been vaccinated. In the most recent survey dated May 20^th, the CDC found that 14.5% of Minnesotans carry COVID immunity not imparted by vaccines.

These studies create important public policy implications. Businesses and schools across the State are trying to make sense of the major CDC policy shift to no masks for vaccinated people cleverly coined as ‘mask confusion” by KSTP-TV. In the Twin Cities, both mayors balked at the CDC move and extended their mask mandates.

The California survey pointing to at least 27 percent of the population holding antibody immunity without vaccines may infer that Minnesota has already arrived at the COVID light-at-the-end-of-the-tunnel (54%+27%= 81 % of population). On the other hand, the CDC survey at 14.5 percent infers that we have not arrived yet. In our own COVID-19 forecast model, it will be two more weeks until the State exceeds 70 percent of the population with antibodies and approximately two more until 75 percent.

The widespread images of Americans partying in large crowds illustrate that for many, Prohibition has already ended. The notion of herd immunity goals may be as fleeting as the morning fog.