COVID-19
Herd Immunity Re-Revisited
1. About herd immunity
Herd immunity means that the population is less likely to transmit disease because of sterilizing immunity. However, people living in such a population can still become ill with same severity as it offers no personal protection from disease. When it is achieved, herd immunity through infection implies that the maximum number of putative infections has been achieved. I would rephrase this to maximum failing of population protection. So why do we think about herd immunity at all?
1.1. How can it be achieved?
Herd immunity is often used in vaccination strategies to protect people that cannot or do not want to be vaccinated. Herd immunity protects others in the populations from becoming contaminated but does not protect against disease after contamination. Contamination might lead to infection and infection might cause disease. A prerequisite is that the immunity is sterilizing i.e., not just protection against the disease but also against infection. However, sterilizing immunity is not yielded by corona- and most other respiratory viruses. Thus, these viruses will not yield herd immunity.
1.2. Why strive for it?
If SARS-2 would be eliminated, no control measures against the virus would be needed, not even testing. This would be a great asset for society and economy, especially for those tourists, travellers, and transport. A test-based society could introduce insecurity for the recreational market of (international) travel agencies, cafes, restaurants, and hotels.
Stopping all government-inflicted anti-corona measures would relieve governments from their duties to compensate companies for economic losses due to the epidemic. It will not stop the economic changes, since people are still likely to make their personal changes based on their perceived levels safety.
Stopping all government-inflicted anti-corona measures would relieve governments from their duties to compensate companies for economic losses due to the epidemic. It will not stop the economic changes, since people are still likely to make their personal changes based on their perceived levels safety.
1.3. Will it work?
Polio and pox yielded life-long sterilizing immunity and are known for their early passage through the blood in the infection. Both viruses have been eliminated by vaccination and societies have become virus-free for those pathogens. Immunity in peripheral blood will eliminate those viruses in the blood.
The successes of eliminating those viruses cannot translated to the immunology of respiratory viruses, like SARS-2. Respiratory viruses lack an early blood passage, and thus need special antibodies to confer immunity against infection. Another difference is the immune evasion strategy of coronaviruses that prevents immunity to last.
The successes of eliminating those viruses cannot translated to the immunology of respiratory viruses, like SARS-2. Respiratory viruses lack an early blood passage, and thus need special antibodies to confer immunity against infection. Another difference is the immune evasion strategy of coronaviruses that prevents immunity to last.
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John. J.L. Jacobs. 18.02.2022
