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| Graphs by the New York Times, adapted by Kentucky Health News |
By Kevin Kavanagh
There is no such thing as “herd immunity” for Covid-19. In this context it is a concept as antiquated as “the Earth is flat.”
The theory was based upon the work of William Farr in 1840 who proposed a bell-shaped curve which illustrated the body’s ability to mount a lasting response to an unchanging pathogen. As stated by one “herd immunity” supporter in the comments section of my previous article on this point, “The disease dies out because enough people have been exposed and developed relative immunity or died that the disease has no means of propagating itself on a large scale.”
That concept was formulated before science knew what viruses and mutations were, and that many biological systems are highly dynamic and constantly adapting. This is eloquently described in Steffanie Strathdee and Thomas Patterson’s book The Perfect Predator. It describes the biological dance between viral phages and their bacterial prey, each one adapting and re-engaging in a duel, the outcome of which is uncertain. With the exception of smallpox, no pathogen has ever been eradicated from the earth and with smallpox, eradication was achieved with a highly effective long-lasting vaccine.
With mutating RNA viruses such as SARS-CoV-2 (which causes Covid-19), “herd immunity” is an extinct construct. Unlike the relatively stable DNA virus of smallpox, RNA viruses have a much higher mutation rate.
That concept was formulated before science knew what viruses and mutations were, and that many biological systems are highly dynamic and constantly adapting. This is eloquently described in Steffanie Strathdee and Thomas Patterson’s book The Perfect Predator. It describes the biological dance between viral phages and their bacterial prey, each one adapting and re-engaging in a duel, the outcome of which is uncertain. With the exception of smallpox, no pathogen has ever been eradicated from the earth and with smallpox, eradication was achieved with a highly effective long-lasting vaccine.
With mutating RNA viruses such as SARS-CoV-2 (which causes Covid-19), “herd immunity” is an extinct construct. Unlike the relatively stable DNA virus of smallpox, RNA viruses have a much higher mutation rate.
If one looks at the U.S. epidemiological curve of SARS-CoV-2, it is a colliding roller coaster and nowhere near a bell curve. We have been hit with variant after variant; Delta infections transitioned to Omicron; and now we are struck by a soup of variants, composed of pathogens harboring a plethora of different immune-avoiding mutations, making the concept of “herd immunity” next to useless.
Unfortunately, SARS-CoV-2 appears to be the most adaptive and dynamic foe we have ever faced and hoping that the antiquated concept of “herd immunity” will save the day, causing SARS-CoV-2 to “miraculously (go) away,” is just pure fantasy.
SARS-CoV-2’s high mutation rate is amplified by its extremely high infectivity. The CDC estimated that the Delta variant was as infectious as chickenpox, which has an R0 of 10 to 12. That means an average person infected with Delta infected 10 to 12 other people. Newer variants have evolved into some of the most infectious pathogens known to man. As the virus spreads it mutates. And as it mutates, it increases its ability to infect, evade our immunity and even attack our immune system.
Evidence is mounting regarding the immune dysfunction caused by SARS-CoV-2. We are seeing a dramatic rise in hospitalizations for the seasonal flu, respiratory syncytial virus (RSV) and even scarlet fever. The increase in RSV hospitalizations has been blamed on immunological weakening during the pandemic due to preventive measures such as masking. However, through November, the United States had correspondingly fewer RSV infections than in 2021, when an RSV surge was also seen. Germany also had a surge in RSV hospitalizations last winter, and now is seeing overwhelming RSV hospitalizations.
Not only does SARS-CoV-2 evade and attack our immunity, but what immunity is produced is fleeting. The virus also resides in a variety of animal hosts where it can mutate and then reinvade the human population. Transmission of a mutated virus from whitetail deer to humans has been documented and there is evidence that Omicron originated in rodents then jumped to humans in South Africa.
The dangers of long Covid, persistent cardiovascular disease, blood clots and a plethora of mental problems caused by Covid-19, are real, and are adversely affecting the health of our workforce and our communities.
Our goal must be to decrease pathogen spread so society can function, with infections decreasing to a level that we can live with the virus. In this regard, it appears the virus is currently winning.
We need to embrace vaccinations, the use of N95 masks in crowded venues, along with home delivery, curbside pickup and outside dining. Indoor air quality must be improved to the point where it is safer indoors than it is outdoors.
If we continue to be a society focused on individualism rather than community or public health, I am afraid we will lose this fight. We need a paradigm shift in the way we strategize to control Covid-19, away from “herd immunity” and towards adapting our lives to live with this highly dynamic and constantly adapting foe.
Kevin Kavanagh is a retired physician from Somerset and chairman of Health Watch USA. This is an edited version of the original article, published in the Courier Journal.
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| New York Times chart, adapted by Ky. Health News; to enlarge, click on it; to download, right-click. |
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