Has CNN not “Heard of Herd?”

Answering the Question: Are We Achieving Herd Immunity?
Tom Rifai, MD, FACP

Here we go again. Believe me, I’m a fan of some people on CNN. And I’m happy to disclose that one CNN contributor is a very good friend. But, facts are facts, right is right, and wrong is wrong. In a CNN email blast I received September 30th was a quick (on a topic that deserves a long and detailed) story entitled “We haven’t come close to achieving herd immunity.” My head went back into my hands…shaking from left to right followed by a sigh (and, honestly, a look to the sky to ask any Higher Power willing to listen, a single word question that I’m sure you can guess). I didn’t find CNN provided the story via any weblink, so I cut and pasted the story below.*

Here’s the bottom line as I’d like to keep this one short on whether or not we are close to reaching herd immunity. Especially in some parts of the country like the east coast, state of Washington, or from where I hail here in “COVID hard hit” Metro Detroit, Michigan: antibodies being present and measurable represent only a small fraction of the number of us able to fight off COVID-19.

Other Ways We’re Achieving Herd Immunity

Full immunological memory of SARS-CoV2 exposure, or such a high level of T-Cell resistance from cross-reactivity to SARS-CoV2 from exposure to any or all of its 4 cold causing coronaviruses (CCC), make any SARS-CoV2 infection extremely mild, if noticeable at all. Let me explain.

In addition to our antibodies, which may well be ephemeral (i.e., sticking around for only a few measurable weeks to months), we have “memory lymphocytes.” These are B and T cells – ready to help ramp up an attack against any future SARS-CoV2 attempts to invade us (either again, or the first time vis-a-vis T-cells with cross reactivity to SARS-CoV2 due to previous corona caused colds – see below).

Lymphocyte white blood cells (there are also neutrophils that fight bacteria and eosinophils that are involved in protecting against other invaders and are implicated often in allergic responses) can either be B-cells ready to quickly turn back into antibody-producing super factories called plasma cells if re-exposed to SARS-CoV2 (the virus that causes COVID-19), or “cytotoxic” (infected cell killing) T-cells. Cytotoxic T-cells are memory immune cells that, unlike antibodies that block a virus particle from infecting a cell, quickly kill virally-infected cells.

The added catch (no pun since we’re talking about colds here) is that not only can we have T-cells that fight this novel coronavirus due to exposure during this pandemic. There are also “cross reactive” cytotoxic T-cells circulating in approximately 30-60% of us. These “cross reactive” cytotoxic T-cells come from a history of infection with one or more of the four cold causing coronaviruses (CCC) constantly circulating the earth (and for which at any point in time 14% of earth’s population may be harboring one or the other). The four CCC are cousins of SARS-CoV2 and similar enough that very convincing data (with all due respect to Dr Fauci) has revealed anywhere from about 30-60% of any population may be harboring pre-emptive resistance to SARS-CoV2 (and therefore to severe COVID-19 if not mild COVID-19) via T-cells that “cross react” with the SARS-CoV2, rooted in past CCCs.

Add to that mucosal IgA antibodies (in your nose and other airways) that bind and block or at least limit SARS-CoV2 from entering our bodies. They are not found in blood testing, nor are there easy access commercial tests for finding T-cell resistance (from CCC), immunity (from actual SARS-CoV2/COVID-19), nor immunity from memory B-cells that are ready and waiting to quickly ramp antibody production against SARS-CoV2 back up upon any re-exposure.

Finally, keep in mind that many who do have antibodies since recovering from COVID-19 (esp. those with mild or asymptomatic disease) and are certainly immune, with rare exception, to even a mild COVID-19 reinfection, don’t harbor high enough antibodies to be detectable by current antibody testing, as opposed to PCR acute infection testing, which has potential for a myriad of false or irrelevant (non-infectious) results.

To look at herd immunity – or what I prefer to call “herd resistance” (which encompasses immunity from past SARS-CoV2 and meaningful resistance to severe COVID-19 from past CCC) – through the limited perspective of detectable antibodies (as the CNN email below sadly did), despite memory B lymphocytes at the ready to bring them back at a virtual moment’s notice upon re-exposure, or despite memory cytotoxic T-cells with long lasting immunity to SARS-CoV2, or from cross reactivity due to exposure to any or all four of the CCC, is truly like being the proverbial blind man on the elephant – except the “blind man” here (the one who looks at herd immunity only from the “eyes” of circulating antibodies) is yelling FIRE in a crowded, scared theater already hot enough emotionally from the horror movie we are watching. Let it be NOTeD that, in the case of the CNN article in question below, we just poured water all over it and put out the fire of fear.


Tom Rifai MD FACP


NIH: Immune cells for common cold may recognize SARS-CoV-2:


Not just antibodies: B cells and T cells mediate immunity to COVID-19:


Dr David Katz:

COVID, Colleges, Case Counts, and Complications: Epidemiology 101, or Drama 101?
*Accompanying “COVID Reality Check” Video: https://youtu.be/urCPH8W2M4Y

Longevity of SARS-CoV-2 memory B cell:


Dr David Katz, COVID Reality Check:

The cure for distorted fear? Data and cold hard mathematics
*Accompanying “COVID Reality Check” Video: https://youtu.be/q6LB2Rp44zA

Evidence for herd immunity in Sweden


*Here is the original story referred to in my first paragraph above:

“CNN Health News

The Results Are In with Sanjay Gupta

We haven’t come close to achieving herd immunity

Just how many people in the United States have been infected with the coronavirus? A new study published in The Lancet on Friday estimates just 9.3% of the population nationwide, with some variations by geography.

The study examined the plasma from more than 28,500 dialysis patients across the country in July,  and found that while 27% of patients, on average, in the Northeast had antibodies against coronavirus — evidence of past infection —  just about 3.5% of patients in the West had antibodies.

In seven states, no dialysis patients had antibodies, while in New York, the epicenter of the outbreak in the spring, the survey found 1 in 3 people had antibodies. The researchers also found that, compared to the White population, residents of predominantly Black and Hispanic neighborhoods were 2 to 3 times more likely to be seropositive while people living in poorer areas were 2 times more likely, and those living in the most densely populated areas were 10 times more likely.

‘This research clearly confirms that despite high rates of Covid-19 in the United States, the number of people with antibodies is still low and we haven’t come close to achieving herd immunity. Until an effective vaccine is approved, we need to make sure our more vulnerable populations are reached with prevention measures,’ Dr. Julie Parsonnet, a professor of medicine at Stanford University who worked on the study, said in a statement.”